hw help

CHAPTER 4

HOW WE PLUG IN

27 percent of 51 billion tons per year

We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.

I wasn’t always aware of how much we rely on electricity, but over the years I’ve gradually come to see how essential it is. And I really appreciate what it takes to deliver this miracle. In fact, it’s fair to say that I’m in awe of all the physical infrastructure that makes electricity so cheap, available, and reliable. It’s downright magical that you can simply turn a switch almost anywhere in a well-off country and expect the lights to come on for a fraction of a penny. Literally: In the United States, leaving a 40-watt lightbulb turned on for an hour costs you about half of one cent.

I’m not the only one in the family who feels this way about electricity: My son, Rory, and I used to visit power plants for fun, just to learn how they worked.

I’m glad I’ve invested all that time learning about electricity. For one thing, it was a great father-son activity. (Seriously.) Besides, figuring out how to get all the benefits of cheap, reliable electricity without emitting greenhouse gases is the single most important thing we must do to avoid a climate disaster. That’s partly because producing electricity is a major contributor to climate change, and also because, if we get zero-carbon electricity, we can use it to help decarbonize lots of other activities, like how we get around and how we make things. The energy we give up by not using coal, natural gas, and oil has to come from somewhere, and mostly it will come from clean electricity. This is why I’m covering electricity first, even though manufacturing is responsible for more emissions.

Plus, even more people should be getting and using electricity. In sub-Saharan Africa, less than half of the population has reliable power at home. *1  And if you don’t have access to any electricity at all, even a seemingly simple task like recharging your mobile phone is difficult and expensive. You have to walk to a store and pay 25 cents or more to plug your phone into an outlet, hundreds of times more than people pay in developed countries.

I don’t expect most people to get as excited about grids and transformers as I do. (Even I can recognize that you have to be a pretty big nerd to write a sentence like “I’m in awe of physical infrastructure.”) But I think if everyone stopped to consider what it takes to deliver the service we now take for granted, they would appreciate it more. And they’d realize that none of us want to give it up. Whatever methods we use to get to zero-carbon electricity in the future will have to be as dependable and nearly as affordable as the ones we use today.

In this chapter I want to explain what it will take to keep getting all the things we like from electricity—a cheap source of energy that’s always available—and deliver it to even more people, but without the carbon emissions. The story starts with how we got here and where we’re headed.

—

Considering how ubiquitous electricity is today, it’s easy to forget that it only became an important factor in most Americans’ lives a few decades into the 20th century. And one of our early major sources of electricity wasn’t any of the ones that we think of today, like coal, oil, or natural gas. It was water, in the form of hydropower.

Hydropower has a lot going for it—it’s relatively cheap—but it also has some big downsides. Making a reservoir displaces local communities and wildlife. When you cover land with water, if there’s a lot of carbon in the soil, the carbon eventually turns into methane and escapes into the atmosphere—which is why studies show that depending on where it’s built, a dam can actually be a worse emitter than coal for 50 to 100 years before it makes up for all the methane it’s responsible for. *2  In addition, the amount of electricity you can generate from a dam depends on the season, because you’re relying on rain-fed streams and rivers. And, of course, hydropower is immobile. You have to build the dams where the rivers are.

Fossil fuels don’t have that limitation. You can take coal, oil, or natural gas out of the ground and move it to a power plant, where you burn it, use the heat to boil water, and let the steam from the boiling water turn a turbine to make electricity.

Because of all these advantages, when demand for electricity in the United States took off after World War II, we met it with fossil fuels. They provided most of the new capacity we built in the second half of the 20th century—some 700 gigawatts, nearly 60 times more than we had installed before the war.

Over time, electricity has become extraordinarily cheap. One study found that it was at least 200 times more affordable in the year 2000 than in 1900. Today, the United States spends only 2 percent of its GDP on electricity, an amazingly low number when you consider how much we rely on it.

The main reason it’s so cheap is that fossil fuels are cheap. They’re widely available, and we’ve developed better and more efficient ways to CHAPTER 4

HOW WE PLUG IN

27 percent of 51 billion tons per year

We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.

I wasn’t always aware of how much we rely on electricity, but over the years I’ve gradually come to see how essential it is. And I really appreciate what it takes to deliver this miracle. In fact, it’s fair to say that I’m in awe of all the physical infrastructure that makes electricity so cheap, available, and reliable. It’s downright magical that you can simply turn a switch almost anywhere in a well-off country and expect the lights to come on for a fraction of a penny. Literally: In the United States, leaving a 40-watt lightbulb turned on for an hour costs you about half of one cent.

I’m not the only one in the family who feels this way about electricity: My son, Rory, and I used to visit power plants for fun, just to learn how they worked.

After a family visit to the Þríhnúkagígur volcano in Iceland in 2015, Rory and I checked out the geothermal power plant next door.

I’m glad I’ve invested all that time learning about electricity. For one thing, it was a great father-son activity. (Seriously.) Besides, figuring out how to get all the benefits of cheap, reliable electricity without emitting greenhouse gases is the single most important thing we must do to avoid a climate disaster. That’s partly because producing electricity is a major contributor to climate change, and also because, if we get zero-carbon electricity, we can use it to help decarbonize lots of other activities, like how we get around and how we make things. The energy we give up by not using coal, natural gas, and oil has to come from somewhere, and mostly it will come from clean electricity. This is why I’m covering electricity first, even though manufacturing is responsible for more emissions.

Plus, even more people should be getting and using electricity. In sub-Saharan Africa, less than half of the population has reliable power at home.*1 And if you don’t have access to any electricity at all, even a seemingly simple task like recharging your mobile phone is difficult and expensive. You have to walk to a store and pay 25 cents or more to plug your phone into an outlet, hundreds of times more than people pay in developed countries.

860 million people don’t have reliable access to electricity. Fewer than half the people in sub-Saharan Africa are on the grid. (IEA)

I don’t expect most people to get as excited about grids and transformers as I do. (Even I can recognize that you have to be a pretty big nerd to write a sentence like “I’m in awe of physical infrastructure.”) But I think if everyone stopped to consider what it takes to deliver the service we now take for granted, they would appreciate it more. And they’d realize that none of us want to give it up. Whatever methods we use to get to zero-carbon electricity in the future will have to be as dependable and nearly as affordable as the ones we use today.

In this chapter I want to explain what it will take to keep getting all the things we like from electricity—a cheap source of energy that’s always available—and deliver it to even more people, but without the carbon emissions. The story starts with how we got here and where we’re headed.

—

Considering how ubiquitous electricity is today, it’s easy to forget that it only became an important factor in most Americans’ lives a few decades into the 20th century. And one of our early major sources of electricity wasn’t any of the ones that we think of today, like coal, oil, or natural gas. It was water, in the form of hydropower.

Hydropower has a lot going for it—it’s relatively cheap—but it also has some big downsides. Making a reservoir displaces local communities and wildlife. When you cover land with water, if there’s a lot of carbon in the soil, the carbon eventually turns into methane and escapes into the atmosphere—which is why studies show that depending on where it’s built, a dam can actually be a worse emitter than coal for 50 to 100 years before it makes up for all the methane it’s responsible for.*2 In addition, the amount of electricity you can generate from a dam depends on the season, because you’re relying on rain-fed streams and rivers. And, of course, hydropower is immobile. You have to build the dams where the rivers are.

Fossil fuels don’t have that limitation. You can take coal, oil, or natural gas out of the ground and move it to a power plant, where you burn it, use the heat to boil water, and let the steam from the boiling water turn a turbine to make electricity.

Because of all these advantages, when demand for electricity in the United States took off after World War II, we met it with fossil fuels. They provided most of the new capacity we built in the second half of the 20th century—some 700 gigawatts, nearly 60 times more than we had installed before the war.

Getting all the world’s electricity from clean sources won’t be easy. Today, fossil fuels account for two-thirds of all electricity generated worldwide. (bp Statistical Review of World Energy 2020)

Over time, electricity has become extraordinarily cheap. One study found that it was at least 200 times more affordable in the year 2000 than in 1900. Today, the United States spends only 2 percent of its GDP on electricity, an amazingly low number when you consider how much we rely on it.

The main reason it’s so cheap is that fossil fuels are cheap. They’re widely available, and we’ve developed better and more efficient ways to extract them and turn them into electricity. Governments also go to considerable effort to keep the prices of fossil fuels low and encourage their production.

In the United States, we’ve been doing this since the earliest days of the Republic: Congress enacted America’s first protective tariff on imported coal in 1789. In the early 1800s, recognizing how important coal was for the railroad industry, states began to exempt it from some taxes and created other incentives for its production. After the corporate income tax was established in 1913, oil and gas producers got the right to deduct certain expenses, including drilling costs. In all, these tax expenditures represented roughly $42 billion (in today’s dollars) in support for coal and natural gas producers from 1950 through 1978, and they’re still in the tax code today. In addition, coal and gas producers benefit from favorable leasing terms on federal lands.

The United States isn’t alone. Most countries take various steps to keep fossil fuels cheap—the International Energy Agency (IEA) estimates that government subsidies for the consumption of fossil fuels amounted to $400 billion in 2018—which helps explain why they’re such a steady part of our electricity supply. The share of global power that comes from burning coal (roughly 40 percent) hasn’t changed in 30 years. Oil and natural gas together have been hovering around 26 percent for three decades. All told, fossil fuels provide two-thirds of the world’s electricity. Solar and wind, meanwhile, account for 7 percent.

As of mid-2019, some 236 gigawatts’ worth of coal plants were being built around the world; coal and natural gas are now the fuels of choice in developing countries, where demand has skyrocketed in the past few decades. Between 2000 and 2018, China tripled the amount of coal power it uses. That’s more capacity than in the United States, Mexico, and Canada combined!

Can we turn this around and get all the electricity we’ll need without any greenhouse gas emissions?

It depends on what you mean by “we.” The United States can get pretty close, with the right policies to expand wind and solar along with a big push for specific innovations. But can the whole world get zero-carbon electricity? That will be much harder.

—

Let’s start with the Green Premiums for electricity in the United States. It’s actually good news: We can eliminate our emissions with only a modest Green Premium.

In the case of electricity, the premium is the additional cost of getting all our power from non-emitting sources, including wind, solar, nuclear power, and coal- and natural-gas-fired plants equipped with devices that capture the carbon they produce. (Remember that the goal isn’t to use only renewable sources like wind and solar; the goal is to get to zero emissions. That’s why I’m including these other zero-carbon options.)

How much is the premium? Changing America’s entire electricity system to zero-carbon sources would raise average retail rates by between 1.3 and 1.7 cents per kilowatt-hour, roughly 15 percent more than what most people pay now. That adds up to a Green Premium of $18 a CHAPTER 4

HOW WE PLUG IN

27 percent of 51 billion tons per year

We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.

I wasn’t always aware of how much we rely on electricity, but over the years I’ve gradually come to see how essential it is. And I really appreciate what it takes to deliver this miracle. In fact, it’s fair to say that I’m in awe of all the physical infrastructure that makes electricity so cheap, available, and reliable. It’s downright magical that you can simply turn a switch almost anywhere in a well-off country and expect the lights to come on for a fraction of a penny. Literally: In the United States, leaving a 40-watt lightbulb turned on for an hour costs you about half of one cent.

I’m not the only one in the family who feels this way about electricity: My son, Rory, and I used to visit power plants for fun, just to learn how they worked.

After a family visit to the Þríhnúkagígur volcano in Iceland in 2015, Rory and I checked out the geothermal power plant next door.

I’m glad I’ve invested all that time learning about electricity. For one thing, it was a great father-son activity. (Seriously.) Besides, figuring out how to get all the benefits of cheap, reliable electricity without emitting greenhouse gases is the single most important thing we must do to avoid a climate disaster. That’s partly because producing electricity is a major contributor to climate change, and also because, if we get zero-carbon electricity, we can use it to help decarbonize lots of other activities, like how we get around and how we make things. The energy we give up by not using coal, natural gas, and oil has to come from somewhere, and mostly it will come from clean electricity. This is why I’m covering electricity first, even though manufacturing is responsible for more emissions.

Plus, even more people should be getting and using electricity. In sub-Saharan Africa, less than half of the population has reliable power at home.*1 And if you don’t have access to any electricity at all, even a seemingly simple task like recharging your mobile phone is difficult and expensive. You have to walk to a store and pay 25 cents or more to plug your phone into an outlet, hundreds of times more than people pay in developed countries.

Chart shows that 600 million people in Sub-Saharan Africa do not have access to reliable electricity, compared to 74 million people in India and 186 million in the rest of the world.

860 million people don’t have reliable access to electricity. Fewer than half the people in sub-Saharan Africa are on the grid. (IEA)

I don’t expect most people to get as excited about grids and transformers as I do. (Even I can recognize that you have to be a pretty big nerd to write a sentence like “I’m in awe of physical infrastructure.”) But I think if everyone stopped to consider what it takes to deliver the service we now take for granted, they would appreciate it more. And they’d realize that none of us want to give it up. Whatever methods we use to get to zero-carbon electricity in the future will have to be as dependable and nearly as affordable as the ones we use today.

In this chapter I want to explain what it will take to keep getting all the things we like from electricity—a cheap source of energy that’s always available—and deliver it to even more people, but without the carbon emissions. The story starts with how we got here and where we’re headed.

—

Considering how ubiquitous electricity is today, it’s easy to forget that it only became an important factor in most Americans’ lives a few decades into the 20th century. And one of our early major sources of electricity wasn’t any of the ones that we think of today, like coal, oil, or natural gas. It was water, in the form of hydropower.

Hydropower has a lot going for it—it’s relatively cheap—but it also has some big downsides. Making a reservoir displaces local communities and wildlife. When you cover land with water, if there’s a lot of carbon in the soil, the carbon eventually turns into methane and escapes into the atmosphere—which is why studies show that depending on where it’s built, a dam can actually be a worse emitter than coal for 50 to 100 years before it makes up for all the methane it’s responsible for.*2 In addition, the amount of electricity you can generate from a dam depends on the season, because you’re relying on rain-fed streams and rivers. And, of course, hydropower is immobile. You have to build the dams where the rivers are.

Fossil fuels don’t have that limitation. You can take coal, oil, or natural gas out of the ground and move it to a power plant, where you burn it, use the heat to boil water, and let the steam from the boiling water turn a turbine to make electricity.

Because of all these advantages, when demand for electricity in the United States took off after World War II, we met it with fossil fuels. They provided most of the new capacity we built in the second half of the 20th century—some 700 gigawatts, nearly 60 times more than we had installed before the war.

Pie chart shows that coal accounts for 36% of worldwide electricity generated, natural gas for 23%, hydropower for 16%, nuclear for 10%, renewables for 11%, oil for 3%, and other energy sources for 1%.

Getting all the world’s electricity from clean sources won’t be easy. Today, fossil fuels account for two-thirds of all electricity generated worldwide. (bp Statistical Review of World Energy 2020)

Over time, electricity has become extraordinarily cheap. One study found that it was at least 200 times more affordable in the year 2000 than in 1900. Today, the United States spends only 2 percent of its GDP on electricity, an amazingly low number when you consider how much we rely on it.

The main reason it’s so cheap is that fossil fuels are cheap. They’re widely available, and we’ve developed better and more efficient ways to extract them and turn them into electricity. Governments also go to considerable effort to keep the prices of fossil fuels low and encourage their production.

In the United States, we’ve been doing this since the earliest days of the Republic: Congress enacted America’s first protective tariff on imported coal in 1789. In the early 1800s, recognizing how important coal was for the railroad industry, states began to exempt it from some taxes and created other incentives for its production. After the corporate income tax was established in 1913, oil and gas producers got the right to deduct certain expenses, including drilling costs. In all, these tax expenditures represented roughly $42 billion (in today’s dollars) in support for coal and natural gas producers from 1950 through 1978, and they’re still in the tax code today. In addition, coal and gas producers benefit from favorable leasing terms on federal lands.

This flyer featuring a coal facility in Connellsville, Pennsylvania, dates from around 1900.

The United States isn’t alone. Most countries take various steps to keep fossil fuels cheap—the International Energy Agency (IEA) estimates that government subsidies for the consumption of fossil fuels amounted to $400 billion in 2018—which helps explain why they’re such a steady part of our electricity supply. The share of global power that comes from burning coal (roughly 40 percent) hasn’t changed in 30 years. Oil and natural gas together have been hovering around 26 percent for three decades. All told, fossil fuels provide two-thirds of the world’s electricity. Solar and wind, meanwhile, account for 7 percent.

As of mid-2019, some 236 gigawatts’ worth of coal plants were being built around the world; coal and natural gas are now the fuels of choice in developing countries, where demand has skyrocketed in the past few decades. Between 2000 and 2018, China tripled the amount of coal power it uses. That’s more capacity than in the United States, Mexico, and Canada combined!

Can we turn this around and get all the electricity we’ll need without any greenhouse gas emissions?

It depends on what you mean by “we.” The United States can get pretty close, with the right policies to expand wind and solar along with a big push for specific innovations. But can the whole world get zero-carbon electricity? That will be much harder.

—

Let’s start with the Green Premiums for electricity in the United States. It’s actually good news: We can eliminate our emissions with only a modest Green Premium.

In the case of electricity, the premium is the additional cost of getting all our power from non-emitting sources, including wind, solar, nuclear power, and coal- and natural-gas-fired plants equipped with devices that capture the carbon they produce. (Remember that the goal isn’t to use only renewable sources like wind and solar; the goal is to get to zero emissions. That’s why I’m including these other zero-carbon options.)

How much is the premium? Changing America’s entire electricity system to zero-carbon sources would raise average retail rates by between 1.3 and 1.7 cents per kilowatt-hour, roughly 15 percent more than what most people pay now. That adds up to a Green Premium of $18 a month for the average home—pretty affordable for most people, though possibly not for low-income Americans, who already spend a tenth of their income on energy.

(You’re probably familiar with kilowatt-hours if you pay a utility bill, because they’re how we’re charged for electricity in our homes. But in case you’re wondering, a kilowatt-hour is a unit of energy that’s used to measure how much electricity you use in a given time period. If you consume one kilowatt for an hour, you’ve used one kilowatt-hour. The typical U.S. household uses 29 kilowatt-hours a day. On average, across all types of customers and states in the United States, a kilowatt-hour of electricity costs around 10 cents, though in some places it can be more than three times that much.)

It’s great that America’s Green Premium could be so low. Europe is similarly well situated; one study by a European trade association suggested that decarbonizing its power grid by 90 to 95 percent would cause average rates to go up about 20 percent. (This study used a different methodology from the way I figured America’s Green Premium.)

Unfortunately, few other countries are so lucky. The United States has a large supply of renewables, including hydropower in the Pacific Northwest, strong winds in the Midwest, and year-round solar power in the Southwest and California. Other countries might have some sun but no wind, or some wind but little year-round sun, or not much of either. And they might have low credit ratings that make it hard to finance big investments in new power plants.

Africa and Asia are in the toughest position. Over the past few decades, China has accomplished one of the greatest feats in history—lifting hundreds of millions of people out of poverty—and did it in part by building coal-fired electric plants very cheaply. Chinese firms drove down the cost of a coal plant by a remarkable 75 percent. And now they understandably want more customers, so they’re making a big play to attract the next wave of developing countries: India, Indonesia, Vietnam, Pakistan, and nations throughout Africa.

What will those potential new customers do? Will they build coal plants or go clean? Consider their goals and their options. Small-scale solar can be an option for people in poor, rural areas who need to charge their cell phones and run lights at night. But that kind of solution is never going to deliver the massive amounts of cheap, always-available electricity these countries need to jump-start their economies. They’re looking to do what China did: grow their economies by attracting industries like manufacturing and call centers—the types of businesses that demand far more (and far more reliable) power than small-scale renewables can provide today.

If these countries opt for coal plants, as China and every rich country did, it’ll be a disaster for the climate. But right now, that’s their most economical option.

—

It’s not immediately obvious why there’s such a thing as a Green Premium in the first place. Natural gas plants have to keep buying fuel as long as they’re running; solar farms, wind farms, and dams get their fuel for free. Also, there’s the truism that as you take a technology to broad scale, it gets cheaper. So why does it cost extra to go green?

One problem is that fossil fuels are so cheap. Because their prices don’t factor in the true cost of climate change—the economic damage they inflict by making the planet warmer—it’s harder for clean energy sources to compete with them. And we’ve spent many decades building up a system to extract fossil fuels from the ground, get energy from them, and deliver that energy, all very cheaply.

Another reason is that, as I mentioned earlier, some regions of the world simply don’t have decent renewable resources. To get close to 100 percent, we’d have to move lots of clean energy from where it’s made (sunny places, ideally near the equator, and windy regions) to where it’s needed (cloudy, windless ones). That would require building new transmission lines, a costly and time-consuming task—especially if it involves crossing national borders—and the more power lines we install, the more the price of power goes up. In fact, transmission and distribution are responsible for more than a third of the final cost of electricity.*3 And many countries don’t want to rely on other countries for their electricity supply.

But cheap oil and expensive transmission lines aren’t the biggest drivers of the electricity Green Premium. The main culprits are our demand for reliability, and the curse of intermittency.

The sun and the wind are intermittent sources, meaning that they don’t generate electricity 24 hours a day, 365 days a year. But our need for power is not intermittent; we want it all the time. So if solar and wind represent a big part of our electricity mix and we want to avoid major outages, we’re going to need other options for when the sun isn’t shining and the wind isn’t blowing. Either we need to store excess electricity in batteries (which, I’ll argue in a moment, is prohibitively expensive), or we need to add other energy sources that use fossil fuels, such as natural gas plants that run only when you need them. Either way, the economics won’t work in our favor. As we approach 100 percent clean electricity, intermittency becomes a bigger and more expensive problem.

The clearest example of intermittency is when the sun goes down, cutting off our supply of solar-generated electricity. Suppose we want to solve that problem by taking one kilowatt-hour of excess electricity that’s generated during the day, storing it, and using it that night. (You’d need much more than that, but I’m picking one kilowatt-hour to make the math easy.) How much would that add to our electric bill?

That depends on two factors: how much the battery costs, and how long it’ll last before we have to replace it. For the cost, let’s say we can buy a one-kilowatt-hour battery for $100. (This is a conservative estimate, and I’ll ignore for the moment what happens if we have to take out a loan for this battery.) As for how long our battery will last, let’s assume it can go through 1,000 charge-and-discharge cycles.

So the capital cost of this one-kilowatt-hour battery will be $100 spread out over 1,000 cycles, which works out to 10 cents per kilowatt-hour. That’s on top of the cost of generating the power in the first place, which in the case of solar power is something like 5 cents per kilowatt-hour. In other words, the electricity we store for nighttime use will cost us triple what we’re paying during the day—5 cents to generate and 10 cents to store, for a total of 15 cents.

I know researchers who think they can make a battery that lasts five times longer than the one I’ve described here. They haven’t done it yet, but if they’re right, that would drive the premium down from 10 cents to 2 cents, a much more modest increase. In any case, the nighttime problem is solvable today, if you’re willing to pay a big premium, and with innovation I’m confident we can reduce that premium.

Unfortunately, nighttime intermittency isn’t the hardest problem to deal with. The seasonal variation between summer and winter is an even bigger hurdle. There are various ways to try to deal with it—like adding in power from a nuclear plant or a gas-fired electric plant fitted with a device that captures its emissions—and any realistic scenario will include these options. I’ll get to them later in the chapter, but for the sake of simplicity for now I’ll just use batteries to illustrate the problem of seasonal variation.

Say we want to store a single kilowatt-hour not for a day but for a whole season. We’ll generate it during the summer and use it in the winter to run a space heater. This time, the battery’s life cycle isn’t an issue, because we’re charging it only once a year.

But suppose we have to finance the purchase of the battery. Now we’ve tied up $100 in capital. (Obviously you wouldn’t finance a $100 battery, but you might need financing if you were buying enough to store several gigawatts. And the math is the same.) If we pay 5 percent interest on the capital, and the battery costs $100, that’s an additional $5 cost to store our single kilowatt-hour. And remember how much we’re paying for solar power during the day: just 5 cents. Who would pay $5 to store a nickel’s worth of electricity?

Seasonal intermittency and the high cost of storage cause yet another problem, especially for big users of solar power—the problem of overgeneration in the summer and undergeneration in the winter.

Because the earth is tilted on its axis, the amount of sunlight that hits any given part of the planet varies across the four seasons, as does the intensity of the sunlight. Just how big the variation is depends on how far you are from the equator. In Ecuador, there’s essentially no change. In the Seattle area, where I live, we get about twice as much sunlight on the longest day of the year as on the shortest day. Parts of Canada and Russia get about 12 times more.*4

To see why this variation matters, let’s do another thought experiment. Imagine there’s a town near Seattle—we’ll call it Suntown—that wants to generate a gigawatt of solar power year-round. How big should Suntown’s solar array be?

One option would be to install enough panels to produce a gigawatt during the summer, when sunlight is plentiful. But the town would be out of luck in the winter, when it’ll get only half as much sunlight. That’s undergeneration. (And the town council is well aware that storage is excessively expensive, so they’ve ruled out batteries.) On the other hand, Suntown could put up all the solar panels it needs for the short, dark days of winter, but then by the time summer arrives, it would be generating way more than necessary. Electricity would be so cheap that the town would be hard-pressed to recoup the expense of installing all those panels.

Suntown could deal with this overgeneration problem by turning off some of its panels during the summer, but then it’d be sinking money into equipment that gets used only for part of the year. That would raise the cost of electricity even more for every home and business in town; in other words, it would add to the town’s Green Premium.

The situation with Suntown isn’t merely a hypothetical example. Something similar has been happening in Germany, which through its ambitious Energiewende program set a goal of 60 percent renewables by 2050. The country has spent billions of dollars over the past decade expanding its use of renewables, increasing its solar capacity nearly 650 percent between 2008 and 2010. But Germany produced about 10 times more solar in June 2018 than it did in December 2018. In fact, at times during the summer, Germany’s solar and wind plants generate so much electricity that the country can’t use it all. When that happens, it ends up transmitting some of the excess to neighboring Poland and the Czech Republic, whose leaders have complained that it’s straining their own power grids and causing unpredictable swings in the cost of electricity.

There’s another problem caused by intermittency, and it’s even harder to solve than the daily or seasonal variety. What happens when an extreme event forces a city to survive several days without any renewable energy at all?

Imagine a future where Tokyo gets all its electricity from wind power alone. (Japan does, in fact, have quite a bit of onshore and offshore wind available.) One August, at the peak of cyclone season, a massive storm hits. The winds are so strong that they will rip the city’s wind turbines apart if they aren’t shut down. Tokyo’s leaders decide to switch off the turbines and get by solely on electricity stored up in the best large-scale batteries they can find.

Here’s the question: How many batteries would they need in order to power Tokyo for three days, until the storm passes and they can turn the turbines back on?

The answer is more than 14 million batteries. That’s more storage capacity than the world produces in a decade. Purchase price: $400 billion. Averaged over the lifetime of the batteries, that’s an annual expense of more than $27 billion.*5 And that’s just the capital cost of the batteries; it doesn’t include other expenses like installation and maintenance.

This example is entirely hypothetical. No one seriously thinks Tokyo should get all its electricity from wind or store all of it in today’s batteries. I’m using this illustration to make a crucial point: It’s extremely difficult and expensive to store electricity on a large scale, but that’s one of the things we’ll need to do if we’re going to rely on intermittent sources to provide a significant percentage of clean electricity in the coming years.

And we’re going to need much more clean electricity in the coming years. Most experts agree that as we electrify other carbon-intensive processes like making steel and running cars, the world’s electricity supply will need to double or even triple by 2050. And that doesn’t even account for population growth, or the fact that people will get richer and use more electricity. So the world will need much more than three times the electricity we generate now.

Because solar and wind are intermittent, our capacity to generate electricity will need to grow even more. (Capacity measures how much electricity we’re theoretically capable of producing when the sun is shining its brightest or the wind is blowing its hardest; generation is how much we actually get, after accounting for intermittency, shutting down power plants for maintenance, and other factors. Generation is always smaller than capacity, and in the case of variable sources like solar and wind it can be a lot smaller.)

With all the additional electricity we’ll be using, and assuming that wind and solar play a significant role, completely decarbonizing America’s power grid by 2050 will require adding around 75 gigawatts of capacity every year for the next 30 years.

Is that a lot? Over the past decade, we’ve added an average of 22 gigawatts a year. Now we need to install more than three times that much each year, and keep up the pace for the next three decades.

That will be a bit easier as we make solar panels and wind turbines cheaper and even more efficient—that is, as we invent ways to get even more energy from a given amount of sunlight or wind. (The best solar panels today convert less than a quarter of the sunlight that hits them into electricity, and the theoretical limit for the most common type of commercially available panels is about 33 percent.) As these conversion rates go up, we can get more power from the same amount of land, which will help as we deploy these technologies widely.

But more efficient panels and turbines aren’t enough, because there’s a major difference between the build-out America did in the 20th century and what we need to do in the 21st. Location is going to matter more than ever.

Since the beginning of the electric grid, utilities have placed most power plants close to America’s rapidly growing cities, because it was relatively easy to use railroads and pipelines to ship fossil fuels from wherever they were extracted to the power plants where they’d be burned to make electricity. As a result, America’s power grid relies on railroads and pipelines to move fuels over long distances to power plants, and then on transmission lines to move electricity over short distances to the cities that need it.

That model doesn’t work with solar and wind. You can’t ship sunlight in a railcar to some power plant; it has to be converted to electricity on the spot. But most of America’s sunlight supply is in the Southwest, and most of our wind is in the Great Plains, far from many major urban areas.

In short, intermittency is the main force that pushes the cost up as we get closer to all zero-carbon electricity. It’s why cities that are trying to go green still supplement solar and wind with other ways to generate electricity, such as gas-fired power plants that can be powered up and down as needed to meet demand, and these so-called peakers are not zero-carbon by any stretch of the imagination.

Just to be clear: Variable energy sources like solar and wind can play a substantial role in getting us to zero. In fact, we need them to. We should be deploying renewables quickly wherever it’s economical to do so. It’s amazing how much the costs of solar and wind power have dropped in the past decade: Solar cells, for example, got almost 10 times cheaper between 2010 and 2020, and the price of a full solar system CHAPTER 4

HOW WE PLUG IN

27 percent of 51 billion tons per year

We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.

I wasn’t always aware of how much we rely on electricity, but over the years I’ve gradually come to see how essential it is. And I really appreciate what it takes to deliver this miracle. In fact, it’s fair to say that I’m in awe of all the physical infrastructure that makes electricity so cheap, available, and reliable. It’s downright magical that you can simply turn a switch almost anywhere in a well-off country and expect the lights to come on for a fraction of a penny. Literally: In the United States, leaving a 40-watt lightbulb turned on for an hour costs you about half of one cent.

I’m not the only one in the family who feels this way about electricity: My son, Rory, and I used to visit power plants for fun, just to learn how they worked.

After a family visit to the Þríhnúkagígur volcano in Iceland in 2015, Rory and I checked out the geothermal power plant next door.

I’m glad I’ve invested all that time learning about electricity. For one thing, it was a great father-son activity. (Seriously.) Besides, figuring out how to get all the benefits of cheap, reliable electricity without emitting greenhouse gases is the single most important thing we must do to avoid a climate disaster. That’s partly because producing electricity is a major contributor to climate change, and also because, if we get zero-carbon electricity, we can use it to help decarbonize lots of other activities, like how we get around and how we make things. The energy we give up by not using coal, natural gas, and oil has to come from somewhere, and mostly it will come from clean electricity. This is why I’m covering electricity first, even though manufacturing is responsible for more emissions.

Plus, even more people should be getting and using electricity. In sub-Saharan Africa, less than half of the population has reliable power at home.*1 And if you don’t have access to any electricity at all, even a seemingly simple task like recharging your mobile phone is difficult and expensive. You have to walk to a store and pay 25 cents or more to plug your phone into an outlet, hundreds of times more than people pay in developed countries.

Chart shows that 600 million people in Sub-Saharan Africa do not have access to reliable electricity, compared to 74 million people in India and 186 million in the rest of the world.

860 million people don’t have reliable access to electricity. Fewer than half the people in sub-Saharan Africa are on the grid. (IEA)

I don’t expect most people to get as excited about grids and transformers as I do. (Even I can recognize that you have to be a pretty big nerd to write a sentence like “I’m in awe of physical infrastructure.”) But I think if everyone stopped to consider what it takes to deliver the service we now take for granted, they would appreciate it more. And they’d realize that none of us want to give it up. Whatever methods we use to get to zero-carbon electricity in the future will have to be as dependable and nearly as affordable as the ones we use today.

In this chapter I want to explain what it will take to keep getting all the things we like from electricity—a cheap source of energy that’s always available—and deliver it to even more people, but without the carbon emissions. The story starts with how we got here and where we’re headed.

—

Considering how ubiquitous electricity is today, it’s easy to forget that it only became an important factor in most Americans’ lives a few decades into the 20th century. And one of our early major sources of electricity wasn’t any of the ones that we think of today, like coal, oil, or natural gas. It was water, in the form of hydropower.

Hydropower has a lot going for it—it’s relatively cheap—but it also has some big downsides. Making a reservoir displaces local communities and wildlife. When you cover land with water, if there’s a lot of carbon in the soil, the carbon eventually turns into methane and escapes into the atmosphere—which is why studies show that depending on where it’s built, a dam can actually be a worse emitter than coal for 50 to 100 years before it makes up for all the methane it’s responsible for.*2 In addition, the amount of electricity you can generate from a dam depends on the season, because you’re relying on rain-fed streams and rivers. And, of course, hydropower is immobile. You have to build the dams where the rivers are.

Fossil fuels don’t have that limitation. You can take coal, oil, or natural gas out of the ground and move it to a power plant, where you burn it, use the heat to boil water, and let the steam from the boiling water turn a turbine to make electricity.

Because of all these advantages, when demand for electricity in the United States took off after World War II, we met it with fossil fuels. They provided most of the new capacity we built in the second half of the 20th century—some 700 gigawatts, nearly 60 times more than we had installed before the war.

Pie chart shows that coal accounts for 36% of worldwide electricity generated, natural gas for 23%, hydropower for 16%, nuclear for 10%, renewables for 11%, oil for 3%, and other energy sources for 1%.

Getting all the world’s electricity from clean sources won’t be easy. Today, fossil fuels account for two-thirds of all electricity generated worldwide. (bp Statistical Review of World Energy 2020)

Over time, electricity has become extraordinarily cheap. One study found that it was at least 200 times more affordable in the year 2000 than in 1900. Today, the United States spends only 2 percent of its GDP on electricity, an amazingly low number when you consider how much we rely on it.

The main reason it’s so cheap is that fossil fuels are cheap. They’re widely available, and we’ve developed better and more efficient ways to extract them and turn them into electricity. Governments also go to considerable effort to keep the prices of fossil fuels low and encourage their production.

In the United States, we’ve been doing this since the earliest days of the Republic: Congress enacted America’s first protective tariff on imported coal in 1789. In the early 1800s, recognizing how important coal was for the railroad industry, states began to exempt it from some taxes and created other incentives for its production. After the corporate income tax was established in 1913, oil and gas producers got the right to deduct certain expenses, including drilling costs. In all, these tax expenditures represented roughly $42 billion (in today’s dollars) in support for coal and natural gas producers from 1950 through 1978, and they’re still in the tax code today. In addition, coal and gas producers benefit from favorable leasing terms on federal lands.

This flyer featuring a coal facility in Connellsville, Pennsylvania, dates from around 1900.

The United States isn’t alone. Most countries take various steps to keep fossil fuels cheap—the International Energy Agency (IEA) estimates that government subsidies for the consumption of fossil fuels amounted to $400 billion in 2018—which helps explain why they’re such a steady part of our electricity supply. The share of global power that comes from burning coal (roughly 40 percent) hasn’t changed in 30 years. Oil and natural gas together have been hovering around 26 percent for three decades. All told, fossil fuels provide two-thirds of the world’s electricity. Solar and wind, meanwhile, account for 7 percent.

As of mid-2019, some 236 gigawatts’ worth of coal plants were being built around the world; coal and natural gas are now the fuels of choice in developing countries, where demand has skyrocketed in the past few decades. Between 2000 and 2018, China tripled the amount of coal power it uses. That’s more capacity than in the United States, Mexico, and Canada combined!

Can we turn this around and get all the electricity we’ll need without any greenhouse gas emissions?

It depends on what you mean by “we.” The United States can get pretty close, with the right policies to expand wind and solar along with a big push for specific innovations. But can the whole world get zero-carbon electricity? That will be much harder.

—

Let’s start with the Green Premiums for electricity in the United States. It’s actually good news: We can eliminate our emissions with only a modest Green Premium.

In the case of electricity, the premium is the additional cost of getting all our power from non-emitting sources, including wind, solar, nuclear power, and coal- and natural-gas-fired plants equipped with devices that capture the carbon they produce. (Remember that the goal isn’t to use only renewable sources like wind and solar; the goal is to get to zero emissions. That’s why I’m including these other zero-carbon options.)

How much is the premium? Changing America’s entire electricity system to zero-carbon sources would raise average retail rates by between 1.3 and 1.7 cents per kilowatt-hour, roughly 15 percent more than what most people pay now. That adds up to a Green Premium of $18 a month for the average home—pretty affordable for most people, though possibly not for low-income Americans, who already spend a tenth of their income on energy.

(You’re probably familiar with kilowatt-hours if you pay a utility bill, because they’re how we’re charged for electricity in our homes. But in case you’re wondering, a kilowatt-hour is a unit of energy that’s used to measure how much electricity you use in a given time period. If you consume one kilowatt for an hour, you’ve used one kilowatt-hour. The typical U.S. household uses 29 kilowatt-hours a day. On average, across all types of customers and states in the United States, a kilowatt-hour of electricity costs around 10 cents, though in some places it can be more than three times that much.)

It’s great that America’s Green Premium could be so low. Europe is similarly well situated; one study by a European trade association suggested that decarbonizing its power grid by 90 to 95 percent would cause average rates to go up about 20 percent. (This study used a different methodology from the way I figured America’s Green Premium.)

Unfortunately, few other countries are so lucky. The United States has a large supply of renewables, including hydropower in the Pacific Northwest, strong winds in the Midwest, and year-round solar power in the Southwest and California. Other countries might have some sun but no wind, or some wind but little year-round sun, or not much of either. And they might have low credit ratings that make it hard to finance big investments in new power plants.

Africa and Asia are in the toughest position. Over the past few decades, China has accomplished one of the greatest feats in history—lifting hundreds of millions of people out of poverty—and did it in part by building coal-fired electric plants very cheaply. Chinese firms drove down the cost of a coal plant by a remarkable 75 percent. And now they understandably want more customers, so they’re making a big play to attract the next wave of developing countries: India, Indonesia, Vietnam, Pakistan, and nations throughout Africa.

What will those potential new customers do? Will they build coal plants or go clean? Consider their goals and their options. Small-scale solar can be an option for people in poor, rural areas who need to charge their cell phones and run lights at night. But that kind of solution is never going to deliver the massive amounts of cheap, always-available electricity these countries need to jump-start their economies. They’re looking to do what China did: grow their economies by attracting industries like manufacturing and call centers—the types of businesses that demand far more (and far more reliable) power than small-scale renewables can provide today.

If these countries opt for coal plants, as China and every rich country did, it’ll be a disaster for the climate. But right now, that’s their most economical option.

—

It’s not immediately obvious why there’s such a thing as a Green Premium in the first place. Natural gas plants have to keep buying fuel as long as they’re running; solar farms, wind farms, and dams get their fuel for free. Also, there’s the truism that as you take a technology to broad scale, it gets cheaper. So why does it cost extra to go green?

One problem is that fossil fuels are so cheap. Because their prices don’t factor in the true cost of climate change—the economic damage they inflict by making the planet warmer—it’s harder for clean energy sources to compete with them. And we’ve spent many decades building up a system to extract fossil fuels from the ground, get energy from them, and deliver that energy, all very cheaply.

Another reason is that, as I mentioned earlier, some regions of the world simply don’t have decent renewable resources. To get close to 100 percent, we’d have to move lots of clean energy from where it’s made (sunny places, ideally near the equator, and windy regions) to where it’s needed (cloudy, windless ones). That would require building new transmission lines, a costly and time-consuming task—especially if it involves crossing national borders—and the more power lines we install, the more the price of power goes up. In fact, transmission and distribution are responsible for more than a third of the final cost of electricity.*3 And many countries don’t want to rely on other countries for their electricity supply.

But cheap oil and expensive transmission lines aren’t the biggest drivers of the electricity Green Premium. The main culprits are our demand for reliability, and the curse of intermittency.

The sun and the wind are intermittent sources, meaning that they don’t generate electricity 24 hours a day, 365 days a year. But our need for power is not intermittent; we want it all the time. So if solar and wind represent a big part of our electricity mix and we want to avoid major outages, we’re going to need other options for when the sun isn’t shining and the wind isn’t blowing. Either we need to store excess electricity in batteries (which, I’ll argue in a moment, is prohibitively expensive), or we need to add other energy sources that use fossil fuels, such as natural gas plants that run only when you need them. Either way, the economics won’t work in our favor. As we approach 100 percent clean electricity, intermittency becomes a bigger and more expensive problem.

The clearest example of intermittency is when the sun goes down, cutting off our supply of solar-generated electricity. Suppose we want to solve that problem by taking one kilowatt-hour of excess electricity that’s generated during the day, storing it, and using it that night. (You’d need much more than that, but I’m picking one kilowatt-hour to make the math easy.) How much would that add to our electric bill?

That depends on two factors: how much the battery costs, and how long it’ll last before we have to replace it. For the cost, let’s say we can buy a one-kilowatt-hour battery for $100. (This is a conservative estimate, and I’ll ignore for the moment what happens if we have to take out a loan for this battery.) As for how long our battery will last, let’s assume it can go through 1,000 charge-and-discharge cycles.

So the capital cost of this one-kilowatt-hour battery will be $100 spread out over 1,000 cycles, which works out to 10 cents per kilowatt-hour. That’s on top of the cost of generating the power in the first place, which in the case of solar power is something like 5 cents per kilowatt-hour. In other words, the electricity we store for nighttime use will cost us triple what we’re paying during the day—5 cents to generate and 10 cents to store, for a total of 15 cents.

I know researchers who think they can make a battery that lasts five times longer than the one I’ve described here. They haven’t done it yet, but if they’re right, that would drive the premium down from 10 cents to 2 cents, a much more modest increase. In any case, the nighttime problem is solvable today, if you’re willing to pay a big premium, and with innovation I’m confident we can reduce that premium.

Unfortunately, nighttime intermittency isn’t the hardest problem to deal with. The seasonal variation between summer and winter is an even bigger hurdle. There are various ways to try to deal with it—like adding in power from a nuclear plant or a gas-fired electric plant fitted with a device that captures its emissions—and any realistic scenario will include these options. I’ll get to them later in the chapter, but for the sake of simplicity for now I’ll just use batteries to illustrate the problem of seasonal variation.

Say we want to store a single kilowatt-hour not for a day but for a whole season. We’ll generate it during the summer and use it in the winter to run a space heater. This time, the battery’s life cycle isn’t an issue, because we’re charging it only once a year.

But suppose we have to finance the purchase of the battery. Now we’ve tied up $100 in capital. (Obviously you wouldn’t finance a $100 battery, but you might need financing if you were buying enough to store several gigawatts. And the math is the same.) If we pay 5 percent interest on the capital, and the battery costs $100, that’s an additional $5 cost to store our single kilowatt-hour. And remember how much we’re paying for solar power during the day: just 5 cents. Who would pay $5 to store a nickel’s worth of electricity?

Seasonal intermittency and the high cost of storage cause yet another problem, especially for big users of solar power—the problem of overgeneration in the summer and undergeneration in the winter.

Because the earth is tilted on its axis, the amount of sunlight that hits any given part of the planet varies across the four seasons, as does the intensity of the sunlight. Just how big the variation is depends on how far you are from the equator. In Ecuador, there’s essentially no change. In the Seattle area, where I live, we get about twice as much sunlight on the longest day of the year as on the shortest day. Parts of Canada and Russia get about 12 times more.*4

To see why this variation matters, let’s do another thought experiment. Imagine there’s a town near Seattle—we’ll call it Suntown—that wants to generate a gigawatt of solar power year-round. How big should Suntown’s solar array be?

One option would be to install enough panels to produce a gigawatt during the summer, when sunlight is plentiful. But the town would be out of luck in the winter, when it’ll get only half as much sunlight. That’s undergeneration. (And the town council is well aware that storage is excessively expensive, so they’ve ruled out batteries.) On the other hand, Suntown could put up all the solar panels it needs for the short, dark days of winter, but then by the time summer arrives, it would be generating way more than necessary. Electricity would be so cheap that the town would be hard-pressed to recoup the expense of installing all those panels.

Suntown could deal with this overgeneration problem by turning off some of its panels during the summer, but then it’d be sinking money into equipment that gets used only for part of the year. That would raise the cost of electricity even more for every home and business in town; in other words, it would add to the town’s Green Premium.

The situation with Suntown isn’t merely a hypothetical example. Something similar has been happening in Germany, which through its ambitious Energiewende program set a goal of 60 percent renewables by 2050. The country has spent billions of dollars over the past decade expanding its use of renewables, increasing its solar capacity nearly 650 percent between 2008 and 2010. But Germany produced about 10 times more solar in June 2018 than it did in December 2018. In fact, at times during the summer, Germany’s solar and wind plants generate so much electricity that the country can’t use it all. When that happens, it ends up transmitting some of the excess to neighboring Poland and the Czech Republic, whose leaders have complained that it’s straining their own power grids and causing unpredictable swings in the cost of electricity.

There’s another problem caused by intermittency, and it’s even harder to solve than the daily or seasonal variety. What happens when an extreme event forces a city to survive several days without any renewable energy at all?

Imagine a future where Tokyo gets all its electricity from wind power alone. (Japan does, in fact, have quite a bit of onshore and offshore wind available.) One August, at the peak of cyclone season, a massive storm hits. The winds are so strong that they will rip the city’s wind turbines apart if they aren’t shut down. Tokyo’s leaders decide to switch off the turbines and get by solely on electricity stored up in the best large-scale batteries they can find.

Here’s the question: How many batteries would they need in order to power Tokyo for three days, until the storm passes and they can turn the turbines back on?

The answer is more than 14 million batteries. That’s more storage capacity than the world produces in a decade. Purchase price: $400 billion. Averaged over the lifetime of the batteries, that’s an annual expense of more than $27 billion.*5 And that’s just the capital cost of the batteries; it doesn’t include other expenses like installation and maintenance.

This example is entirely hypothetical. No one seriously thinks Tokyo should get all its electricity from wind or store all of it in today’s batteries. I’m using this illustration to make a crucial point: It’s extremely difficult and expensive to store electricity on a large scale, but that’s one of the things we’ll need to do if we’re going to rely on intermittent sources to provide a significant percentage of clean electricity in the coming years.

And we’re going to need much more clean electricity in the coming years. Most experts agree that as we electrify other carbon-intensive processes like making steel and running cars, the world’s electricity supply will need to double or even triple by 2050. And that doesn’t even account for population growth, or the fact that people will get richer and use more electricity. So the world will need much more than three times the electricity we generate now.

Because solar and wind are intermittent, our capacity to generate electricity will need to grow even more. (Capacity measures how much electricity we’re theoretically capable of producing when the sun is shining its brightest or the wind is blowing its hardest; generation is how much we actually get, after accounting for intermittency, shutting down power plants for maintenance, and other factors. Generation is always smaller than capacity, and in the case of variable sources like solar and wind it can be a lot smaller.)

With all the additional electricity we’ll be using, and assuming that wind and solar play a significant role, completely decarbonizing America’s power grid by 2050 will require adding around 75 gigawatts of capacity every year for the next 30 years.

Is that a lot? Over the past decade, we’ve added an average of 22 gigawatts a year. Now we need to install more than three times that much each year, and keep up the pace for the next three decades.

That will be a bit easier as we make solar panels and wind turbines cheaper and even more efficient—that is, as we invent ways to get even more energy from a given amount of sunlight or wind. (The best solar panels today convert less than a quarter of the sunlight that hits them into electricity, and the theoretical limit for the most common type of commercially available panels is about 33 percent.) As these conversion rates go up, we can get more power from the same amount of land, which will help as we deploy these technologies widely.

But more efficient panels and turbines aren’t enough, because there’s a major difference between the build-out America did in the 20th century and what we need to do in the 21st. Location is going to matter more than ever.

Since the beginning of the electric grid, utilities have placed most power plants close to America’s rapidly growing cities, because it was relatively easy to use railroads and pipelines to ship fossil fuels from wherever they were extracted to the power plants where they’d be burned to make electricity. As a result, America’s power grid relies on railroads and pipelines to move fuels over long distances to power plants, and then on transmission lines to move electricity over short distances to the cities that need it.

That model doesn’t work with solar and wind. You can’t ship sunlight in a railcar to some power plant; it has to be converted to electricity on the spot. But most of America’s sunlight supply is in the Southwest, and most of our wind is in the Great Plains, far from many major urban areas.

In short, intermittency is the main force that pushes the cost up as we get closer to all zero-carbon electricity. It’s why cities that are trying to go green still supplement solar and wind with other ways to generate electricity, such as gas-fired power plants that can be powered up and down as needed to meet demand, and these so-called peakers are not zero-carbon by any stretch of the imagination.

Just to be clear: Variable energy sources like solar and wind can play a substantial role in getting us to zero. In fact, we need them to. We should be deploying renewables quickly wherever it’s economical to do so. It’s amazing how much the costs of solar and wind power have dropped in the past decade: Solar cells, for example, got almost 10 times cheaper between 2010 and 2020, and the price of a full solar system went down by 11 percent in 2019 alone. A lot of the credit for these decreases goes to learning by doing—the simple fact that the more times we make some product, the better we get at it.

We do need to remove the barriers that keep us from making the most of renewable sources. For example, it’s natural to think of America’s electric grid as one single connected network, but in reality it’s nothing of the sort. There isn’t one power grid; there are many, and they’re a patchwork mess that makes it essentially impossible to send electricity beyond the region where it’s made. Arizona can sell spare solar power to its neighbors, but not to a state on the other side of the country.

We could solve this problem by crisscrossing the country with thousands of miles of special long-distance power lines carrying what’s called high-voltage current. This technology already exists; in fact, the United States already has some of these lines installed. (The biggest one runs from Washington State to California.) But the political hurdles to a massive upgrade of our electric grid are considerable.

Just think about how many landowners, utility companies, and local and state governments you’d need to bring together to build power lines that could move solar energy from the Southwest all the way to customers in New England. Merely picking the routes and establishing rights-of-way would be a massive undertaking; people tend to object when you want to run a big power line through the local park.

Construction on the TransWest Express, a transmission project designed to move wind-generated power from Wyoming to California and the Southwest, is scheduled to begin in 2021. The project is supposed to become operational in 2024—some 17 years after planning began.

But if we could pull this off, it would be transformative. I’m funding a project that involves building a computer model of all the power grids covering the United States. Using the model, experts have studied what it would take for all western states to reach California’s goal of 60 percent renewables by 2030, and for all eastern states to reach New York’s goal of 70 percent clean energy by that same year. What they found is that there’s simply no way for the states to do it without enhancing the power grid. The model also showed that regional and national approaches to transmission—rather than leaving each state to its own devices—would allow every state to meet the emission-reduction goals with 30 percent fewer renewables than they would need otherwise. In other words, we’ll save money by building renewables in the best locations, building a unified national grid, and shipping zero-emissions electrons wherever they’re needed.*6

In the coming years, as electricity becomes an even bigger part of our overall energy diet, we’ll need models like these for grids around the world. They’ll help us answer questions like: Which mix of clean energy sources will be the most efficient in a given place? Where should transmission lines go? Which regulations stand in the way, and what incentives do we need to create? I hope to see a lot more projects like this one.

Here’s another complication: As our houses rely less on fossil fuels and more on electricity (for example, to power electric cars and stay warm in the winter), we’ll need to upgrade the electrical service to each household—by at least a factor of two, and in many cases even more than that. A lot of streets will need to be dug up and electrical poles climbed to install heavier wires, transformers, and other equipment. So it will be felt in a real way by nearly every community, and the political impact will get down to the local level.

Technology might be able to help overcome some of the political barriers involved with these upgrades. For example, power lines are less of an eyesore if they’re run underground. But today, burying power lines increases the cost by a factor of 5 to 10. (The problem is heat: Power lines get hot when there’s electricity running through them. That’s no problem when they’re aboveground—the heat just dissipates into the air—but underground there’s no place for the heat to go. If the temperature gets too high, the power lines melt.) Some companies are working on next-generation transmission that would eliminate the heat problem and reduce the cost of underground lines significantly.

Deploying today’s renewables and improving transmission couldn’t be more important. If we don’t upgrade our grid significantly and CHAPTER 4

HOW WE PLUG IN

27 percent of 51 billion tons per year

We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.

I wasn’t always aware of how much we rely on electricity, but over the years I’ve gradually come to see how essential it is. And I really appreciate what it takes to deliver this miracle. In fact, it’s fair to say that I’m in awe of all the physical infrastructure that makes electricity so cheap, available, and reliable. It’s downright magical that you can simply turn a switch almost anywhere in a well-off country and expect the lights to come on for a fraction of a penny. Literally: In the United States, leaving a 40-watt lightbulb turned on for an hour costs you about half of one cent.

I’m not the only one in the family who feels this way about electricity: My son, Rory, and I used to visit power plants for fun, just to learn how they worked.

After a family visit to the Þríhnúkagígur volcano in Iceland in 2015, Rory and I checked out the geothermal power plant next door.

I’m glad I’ve invested all that time learning about electricity. For one thing, it was a great father-son activity. (Seriously.) Besides, figuring out how to get all the benefits of cheap, reliable electricity without emitting greenhouse gases is the single most important thing we must do to avoid a climate disaster. That’s partly because producing electricity is a major contributor to climate change, and also because, if we get zero-carbon electricity, we can use it to help decarbonize lots of other activities, like how we get around and how we make things. The energy we give up by not using coal, natural gas, and oil has to come from somewhere, and mostly it will come from clean electricity. This is why I’m covering electricity first, even though manufacturing is responsible for more emissions.

Plus, even more people should be getting and using electricity. In sub-Saharan Africa, less than half of the population has reliable power at home. *1  And if you don’t have access to any electricity at all, even a seemingly simple task like recharging your mobile phone is difficult and expensive. You have to walk to a store and pay 25 cents or more to plug your phone into an outlet, hundreds of times more than people pay in developed countries.

860 million people don’t have reliable access to electricity. Fewer than half the people in sub-Saharan Africa are on the grid. (IEA)

I don’t expect most people to get as excited about grids and transformers as I do. (Even I can recognize that you have to be a pretty big nerd to write a sentence like “I’m in awe of physical infrastructure.”) But I think if everyone stopped to consider what it takes to deliver the service we now take for granted, they would appreciate it more. And they’d realize that none of us want to give it up. Whatever methods we use to get to zero-carbon electricity in the future will have to be as dependable and nearly as affordable as the ones we use today.

In this chapter I want to explain what it will take to keep getting all the things we like from electricity—a cheap source of energy that’s always available—and deliver it to even more people, but without the carbon emissions. The story starts with how we got here and where we’re headed.

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Considering how ubiquitous electricity is today, it’s easy to forget that it only became an important factor in most Americans’ lives a few decades into the 20th century. And one of our early major sources of electricity wasn’t any of the ones that we think of today, like coal, oil, or natural gas. It was water, in the form of hydropower.

Hydropower has a lot going for it—it’s relatively cheap—but it also has some big downsides. Making a reservoir displaces local communities and wildlife. When you cover land with water, if there’s a lot of carbon in the soil, the carbon eventually turns into methane and escapes into the atmosphere—which is why studies show that depending on where it’s built, a dam can actually be a worse emitter than coal for 50 to 100 years before it makes up for all the methane it’s responsible for. *2  In addition, the amount of electricity you can generate from a dam depends on the season, because you’re relying on rain-fed streams and rivers. And, of course, hydropower is immobile. You have to build the dams where the rivers are.

Fossil fuels don’t have that limitation. You can take coal, oil, or natural gas out of the ground and move it to a power plant, where you burn it, use the heat to boil water, and let the steam from the boiling water turn a turbine to make electricity.

Because of all these advantages, when demand for electricity in the United States took off after World War II, we met it with fossil fuels. They provided most of the new capacity we built in the second half of the 20th century—some 700 gigawatts, nearly 60 times more than we had installed before the war.

Getting all the world’s electricity from clean sources won’t be easy. Today, fossil fuels account for two-thirds of all electricity generated worldwide. (bp Statistical Review of World Energy 2020)

Over time, electricity has become extraordinarily cheap. One study found that it was at least 200 times more affordable in the year 2000 than in 1900. Today, the United States spends only 2 percent of its GDP on electricity, an amazingly low number when you consider how much we rely on it.

The main reason it’s so cheap is that fossil fuels are cheap. They’re widely available, and we’ve developed better and more efficient ways to extract them and turn them into electricity. Governments also go to considerable effort to keep the prices of fossil fuels low and encourage their production.

In the United States, we’ve been doing this since the earliest days of the Republic: Congress enacted America’s first protective tariff on imported coal in 1789. In the early 1800s, recognizing how important coal was for the railroad industry, states began to exempt it from some taxes and created other incentives for its production. After the corporate income tax was established in 1913, oil and gas producers got the right to deduct certain expenses, including drilling costs. In all, these tax expenditures represented roughly $42 billion (in today’s dollars) in support for coal and natural gas producers from 1950 through 1978, and they’re still in the tax code today. In addition, coal and gas producers benefit from favorable leasing terms on federal lands.

This flyer featuring a coal facility in Connellsville, Pennsylvania, dates from around 1900.

The United States isn’t alone. Most countries take various steps to keep fossil fuels cheap—the International Energy Agency (IEA) estimates that government subsidies for the consumption of fossil fuels amounted to $400 billion in 2018—which helps explain why they’re such a steady part of our electricity supply. The share of global power that comes from burning coal (roughly 40 percent) hasn’t changed in 30 years. Oil and natural gas together have been hovering around 26 percent for three decades. All told, fossil fuels provide two-thirds of the world’s electricity. Solar and wind, meanwhile, account for 7 percent.

As of mid-2019, some 236 gigawatts’ worth of coal plants were being built around the world; coal and natural gas are now the fuels of choice in developing countries, where demand has skyrocketed in the past few decades. Between 2000 and 2018, China tripled the amount of coal power it uses. That’s more capacity than in the United States, Mexico, and Canada combined!

Can we turn this around and get all the electricity we’ll need without any greenhouse gas emissions?

It depends on what you mean by “we.” The United States can get pretty close, with the right policies to expand wind and solar along with a big push for specific innovations. But can the whole world get zero-carbon electricity? That will be much harder.

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Let’s start with the Green Premiums for electricity in the United States. It’s actually good news: We can eliminate our emissions with only a modest Green Premium.

In the case of electricity, the premium is the additional cost of getting all our power from non-emitting sources, including wind, solar, nuclear power, and coal- and natural-gas-fired plants equipped with devices that capture the carbon they produce. (Remember that the goal isn’t to use only renewable sources like wind and solar; the goal is to get to zero emissions. That’s why I’m including these other zero-carbon options.)

How much is the premium? Changing America’s entire electricity system to zero-carbon sources would raise average retail rates by between 1.3 and 1.7 cents per kilowatt-hour, roughly 15 percent more than what most people pay now. That adds up to a Green Premium of $18 a month for the average home—pretty affordable for most people, though possibly not for low-income Americans, who already spend a tenth of their income on energy.

(You’re probably familiar with kilowatt-hours if you pay a utility bill, because they’re how we’re charged for electricity in our homes. But in case you’re wondering, a kilowatt-hour is a unit of energy that’s used to measure how much electricity you use in a given time period. If you consume one kilowatt for an hour, you’ve used one kilowatt-hour. The typical U.S. household uses 29 kilowatt-hours a day. On average, across all types of customers and states in the United States, a kilowatt-hour of electricity costs around 10 cents, though in some places it can be more than three times that much.)

It’s great that America’s Green Premium could be so low. Europe is similarly well situated; one study by a European trade association suggested that decarbonizing its power grid by 90 to 95 percent would cause average rates to go up about 20 percent. (This study used a different methodology from the way I figured America’s Green Premium.)

Unfortunately, few other countries are so lucky. The United States has a large supply of renewables, including hydropower in the Pacific Northwest, strong winds in the Midwest, and year-round solar power in the Southwest and California. Other countries might have some sun but no wind, or some wind but little year-round sun, or not much of either. And they might have low credit ratings that make it hard to finance big investments in new power plants.

Africa and Asia are in the toughest position. Over the past few decades, China has accomplished one of the greatest feats in history—lifting hundreds of millions of people out of poverty—and did it in part by building coal-fired electric plants very cheaply. Chinese firms drove down the cost of a coal plant by a remarkable 75 percent. And now they understandably want more customers, so they’re making a big play to attract the next wave of developing countries: India, Indonesia, Vietnam, Pakistan, and nations throughout Africa.

What will those potential new customers do? Will they build coal plants or go clean? Consider their goals and their options. Small-scale solar can be an option for people in poor, rural areas who need to charge their cell phones and run lights at night. But that kind of solution is never going to deliver the massive amounts of cheap, always-available electricity these countries need to jump-start their economies. They’re looking to do what China did: grow their economies by attracting industries like manufacturing and call centers—the types of businesses that demand far more (and far more reliable) power than small-scale renewables can provide today.

If these countries opt for coal plants, as China and every rich country did, it’ll be a disaster for the climate. But right now, that’s their most economical option.

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It’s not immediately obvious why there’s such a thing as a Green Premium in the first place. Natural gas plants have to keep buying fuel as long as they’re running; solar farms, wind farms, and dams get their fuel for free. Also, there’s the truism that as you take a technology to broad scale, it gets cheaper. So why does it cost extra to go green?

One problem is that fossil fuels are so cheap. Because their prices don’t factor in the true cost of climate change—the economic damage they inflict by making the planet warmer—it’s harder for clean energy sources to compete with them. And we’ve spent many decades building up a system to extract fossil fuels from the ground, get energy from them, and deliver that energy, all very cheaply.

Another reason is that, as I mentioned earlier, some regions of the world simply don’t have decent renewable resources. To get close to 100 percent, we’d have to move lots of clean energy from where it’s made (sunny places, ideally near the equator, and windy regions) to where it’s needed (cloudy, windless ones). That would require building new transmission lines, a costly and time-consuming task—especially if it involves crossing national borders—and the more power lines we install, the more the price of power goes up. In fact, transmission and distribution are responsible for more than a third of the final cost of electricity. *3  And many countries don’t want to rely on other countries for their electricity supply.

But cheap oil and expensive transmission lines aren’t the biggest drivers of the electricity Green Premium. The main culprits are our demand for reliability, and the curse of intermittency.

The sun and the wind are intermittent sources, meaning that they don’t generate electricity 24 hours a day, 365 days a year. But our need for power is not intermittent; we want it all the time. So if solar and wind represent a big part of our electricity mix and we want to avoid major outages, we’re going to need other options for when the sun isn’t shining and the wind isn’t blowing. Either we need to store excess electricity in batteries (which, I’ll argue in a moment, is prohibitively expensive), or we need to add other energy sources that use fossil fuels, such as natural gas plants that run only when you need them. Either way, the economics won’t work in our favor. As we approach 100 percent clean electricity, intermittency becomes a bigger and more expensive problem.

The clearest example of intermittency is when the sun goes down, cutting off our supply of solar-generated electricity. Suppose we want to solve that problem by taking one kilowatt-hour of excess electricity that’s generated during the day, storing it, and using it that night. (You’d need much more than that, but I’m picking one kilowatt-hour to make the math easy.) How much would that add to our electric bill?

That depends on two factors: how much the battery costs, and how long it’ll last before we have to replace it. For the cost, let’s say we can buy a one-kilowatt-hour battery for $100. (This is a conservative estimate, and I’ll ignore for the moment what happens if we have to take out a loan for this battery.) As for how long our battery will last, let’s assume it can go through 1,000 charge-and-discharge cycles.

So the capital cost of this one-kilowatt-hour battery will be $100 spread out over 1,000 cycles, which works out to 10 cents per kilowatt-hour. That’s on top of the cost of generating the power in the first place, which in the case of solar power is something like 5 cents per kilowatt-hour. In other words, the electricity we store for nighttime use will cost us triple what we’re paying during the day—5 cents to generate and 10 cents to store, for a total of 15 cents.

I know researchers who think they can make a battery that lasts five times longer than the one I’ve described here. They haven’t done it yet, but if they’re right, that would drive the premium down from 10 cents to 2 cents, a much more modest increase. In any case, the nighttime problem is solvable today, if you’re willing to pay a big premium, and with innovation I’m confident we can reduce that premium.

Unfortunately, nighttime intermittency isn’t the hardest problem to deal with. The seasonal variation between summer and winter is an even bigger hurdle. There are various ways to try to deal with it—like adding in power from a nuclear plant or a gas-fired electric plant fitted with a device that captures its emissions—and any realistic scenario will include these options. I’ll get to them later in the chapter, but for the sake of simplicity for now I’ll just use batteries to illustrate the problem of seasonal variation.

Say we want to store a single kilowatt-hour not for a day but for a whole season. We’ll generate it during the summer and use it in the winter to run a space heater. This time, the battery’s life cycle isn’t an issue, because we’re charging it only once a year.

But suppose we have to finance the purchase of the battery. Now we’ve tied up $100 in capital. (Obviously you wouldn’t finance a $100 battery, but you might need financing if you were buying enough to store several gigawatts. And the math is the same.) If we pay 5 percent interest on the capital, and the battery costs $100, that’s an additional $5 cost to store our single kilowatt-hour. And remember how much we’re paying for solar power during the day: just 5 cents. Who would pay $5 to store a nickel’s worth of electricity?

Seasonal intermittency and the high cost of storage cause yet another problem, especially for big users of solar power—the problem of overgeneration in the summer and undergeneration in the winter.

Because the earth is tilted on its axis, the amount of sunlight that hits any given part of the planet varies across the four seasons, as does the intensity of the sunlight. Just how big the variation is depends on how far you are from the equator. In Ecuador, there’s essentially no change. In the Seattle area, where I live, we get about twice as much sunlight on the longest day of the year as on the shortest day. Parts of Canada and Russia get about 12 times more. *4

To see why this variation matters, let’s do another thought experiment. Imagine there’s a town near Seattle—we’ll call it Suntown—that wants to generate a gigawatt of solar power year-round. How big should Suntown’s solar array be?

One option would be to install enough panels to produce a gigawatt during the summer, when sunlight is plentiful. But the town would be out of luck in the winter, when it’ll get only half as much sunlight. That’s undergeneration. (And the town council is well aware that storage is excessively expensive, so they’ve ruled out batteries.) On the other hand, Suntown could put up all the solar panels it needs for the short, dark days of winter, but then by the time summer arrives, it would be generating way more than necessary. Electricity would be so cheap that the town would be hard-pressed to recoup the expense of installing all those panels.

Suntown could deal with this overgeneration problem by turning off some of its panels during the summer, but then it’d be sinking money into equipment that gets used only for part of the year. That would raise the cost of electricity even more for every home and business in town; in other words, it would add to the town’s Green Premium.

The situation with Suntown isn’t merely a hypothetical example. Something similar has been happening in Germany, which through its ambitious Energiewende program set a goal of 60 percent renewables by 2050. The country has spent billions of dollars over the past decade expanding its use of renewables, increasing its solar capacity nearly 650 percent between 2008 and 2010. But Germany produced about 10 times more solar in June 2018 than it did in December 2018. In fact, at times during the summer, Germany’s solar and wind plants generate so much electricity that the country can’t use it all. When that happens, it ends up transmitting some of the excess to neighboring Poland and the Czech Republic, whose leaders have complained that it’s straining their own power grids and causing unpredictable swings in the cost of electricity.

There’s another problem caused by intermittency, and it’s even harder to solve than the daily or seasonal variety. What happens when an extreme event forces a city to survive several days without any renewable energy at all?

Imagine a future where Tokyo gets all its electricity from wind power alone. (Japan does, in fact, have quite a bit of onshore and offshore wind available.) One August, at the peak of cyclone season, a massive storm hits. The winds are so strong that they will rip the city’s wind turbines apart if they aren’t shut down. Tokyo’s leaders decide to switch off the turbines and get by solely on electricity stored up in the best large-scale batteries they can find.

Here’s the question: How many batteries would they need in order to power Tokyo for three days, until the storm passes and they can turn the turbines back on?

The answer is more than 14 million batteries. That’s more storage capacity than the world produces in a decade. Purchase price: $400 billion. Averaged over the lifetime of the batteries, that’s an annual expense of more than $27 billion. *5  And that’s just the capital cost of the batteries; it doesn’t include other expenses like installation and maintenance.

This example is entirely hypothetical. No one seriously thinks Tokyo should get all its electricity from wind or store all of it in today’s batteries. I’m using this illustration to make a crucial point: It’s extremely difficult and expensive to store electricity on a large scale, but that’s one of the things we’ll need to do if we’re going to rely on intermittent sources to provide a significant percentage of clean electricity in the coming years.

And we’re going to need much more clean electricity in the coming years. Most experts agree that as we electrify other carbon-intensive processes like making steel and running cars, the world’s electricity supply will need to double or even triple by 2050. And that doesn’t even account for population growth, or the fact that people will get richer and use more electricity. So the world will need much more than three times the electricity we generate now.

Because solar and wind are intermittent, our capacity to generate electricity will need to grow even more. (Capacity measures how much electricity we’re theoretically capable of producing when the sun is shining its brightest or the wind is blowing its hardest; generation is how much we actually get, after accounting for intermittency, shutting down power plants for maintenance, and other factors. Generation is always smaller than capacity, and in the case of variable sources like solar and wind it can be a lot smaller.)

With all the additional electricity we’ll be using, and assuming that wind and solar play a significant role, completely decarbonizing America’s power grid by 2050 will require adding around 75 gigawatts of capacity every year for the next 30 years.

Is that a lot? Over the past decade, we’ve added an average of 22 gigawatts a year. Now we need to install more than three times that much each year, and keep up the pace for the next three decades.

That will be a bit easier as we make solar panels and wind turbines cheaper and even more efficient—that is, as we invent ways to get even more energy from a given amount of sunlight or wind. (The best solar panels today convert less than a quarter of the sunlight that hits them into electricity, and the theoretical limit for the most common type of commercially available panels is about 33 percent.) As these conversion rates go up, we can get more power from the same amount of land, which will help as we deploy these technologies widely.

But more efficient panels and turbines aren’t enough, because there’s a major difference between the build-out America did in the 20th century and what we need to do in the 21st. Location is going to matter more than ever.

Since the beginning of the electric grid, utilities have placed most power plants close to America’s rapidly growing cities, because it was relatively easy to use railroads and pipelines to ship fossil fuels from wherever they were extracted to the power plants where they’d be burned to make electricity. As a result, America’s power grid relies on railroads and pipelines to move fuels over long distances to power plants, and then on transmission lines to move electricity over short distances to the cities that need it.

That model doesn’t work with solar and wind. You can’t ship sunlight in a railcar to some power plant; it has to be converted to electricity on the spot. But most of America’s sunlight supply is in the Southwest, and most of our wind is in the Great Plains, far from many major urban areas.

In short, intermittency is the main force that pushes the cost up as we get closer to all zero-carbon electricity. It’s why cities that are trying to go green still supplement solar and wind with other ways to generate electricity, such as gas-fired power plants that can be powered up and down as needed to meet demand, and these so-called peakers are not zero-carbon by any stretch of the imagination.

Just to be clear: Variable energy sources like solar and wind can play a substantial role in getting us to zero. In fact, we need them to. We should be deploying renewables quickly wherever it’s economical to do so. It’s amazing how much the costs of solar and wind power have dropped in the past decade: Solar cells, for example, got almost 10 times cheaper between 2010 and 2020, and the price of a full solar system went down by 11 percent in 2019 alone. A lot of the credit for these decreases goes to learning by doing—the simple fact that the more times we make some product, the better we get at it.

We do need to remove the barriers that keep us from making the most of renewable sources. For example, it’s natural to think of America’s electric grid as one single connected network, but in reality it’s nothing of the sort. There isn’t one power grid; there are many, and they’re a patchwork mess that makes it essentially impossible to send electricity beyond the region where it’s made. Arizona can sell spare solar power to its neighbors, but not to a state on the other side of the country.

We could solve this problem by crisscrossing the country with thousands of miles of special long-distance power lines carrying what’s called high-voltage current. This technology already exists; in fact, the United States already has some of these lines installed. (The biggest one runs from Washington State to California.) But the political hurdles to a massive upgrade of our electric grid are considerable.

Just think about how many landowners, utility companies, and local and state governments you’d need to bring together to build power lines that could move solar energy from the Southwest all the way to customers in New England. Merely picking the routes and establishing rights-of-way would be a massive undertaking; people tend to object when you want to run a big power line through the local park.

Construction on the TransWest Express, a transmission project designed to move wind-generated power from Wyoming to California and the Southwest, is scheduled to begin in 2021. The project is supposed to become operational in 2024—some 17 years after planning began.

But if we could pull this off, it would be transformative. I’m funding a project that involves building a computer model of all the power grids covering the United States. Using the model, experts have studied what it would take for all western states to reach California’s goal of 60 percent renewables by 2030, and for all eastern states to reach New York’s goal of 70 percent clean energy by that same year. What they found is that there’s simply no way for the states to do it without enhancing the power grid. The model also showed that regional and national approaches to transmission—rather than leaving each state to its own devices—would allow every state to meet the emission-reduction goals with 30 percent fewer renewables than they would need otherwise. In other words, we’ll save money by building renewables in the best locations, building a unified national grid, and shipping zero-emissions electrons wherever they’re needed. *6

In the coming years, as electricity becomes an even bigger part of our overall energy diet, we’ll need models like these for grids around the world. They’ll help us answer questions like: Which mix of clean energy sources will be the most efficient in a given place? Where should transmission lines go? Which regulations stand in the way, and what incentives do we need to create? I hope to see a lot more projects like this one.

Here’s another complication: As our houses rely less on fossil fuels and more on electricity (for example, to power electric cars and stay warm in the winter), we’ll need to upgrade the electrical service to each household—by at least a factor of two, and in many cases even more than that. A lot of streets will need to be dug up and electrical poles climbed to install heavier wires, transformers, and other equipment. So it will be felt in a real way by nearly every community, and the political impact will get down to the local level.

Technology might be able to help overcome some of the political barriers involved with these upgrades. For example, power lines are less of an eyesore if they’re run underground. But today, burying power lines increases the cost by a factor of 5 to 10. (The problem is heat: Power lines get hot when there’s electricity running through them. That’s no problem when they’re aboveground—the heat just dissipates into the air—but underground there’s no place for the heat to go. If the temperature gets too high, the power lines melt.) Some companies are working on next-generation transmission that would eliminate the heat problem and reduce the cost of underground lines significantly.

Deploying today’s renewables and improving transmission couldn’t be more important. If we don’t upgrade our grid significantly and instead make each region do this on its own, the Green Premium might not be 15 to 30 percent; it could be 100 percent or more. Unless we use large amounts of nuclear energy (which I’ll get to in the next section), every path to zero in the United States will require us to install as much wind and solar power as we can build and find room for. It’s hard to say exactly how much of America’s electricity will come from renewables in the end, but what we do know is that between now and 2050 we have to build them much faster—on the order of 5 to 10 times faster—than we’re doing right now.

And remember that most countries aren’t as lucky as the United States when it comes to solar and wind resources. The fact that we can hope to generate a large percentage of our power from renewables is the exception rather than the rule. That’s why, even as we deploy, deploy, deploy solar and wind, the world is going to need some new clean electricity inventions too.

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There’s already a lot of great research going on. If there’s one thing I love about my work, it’s the opportunity to meet with, and learn from, top scientists and entrepreneurs. Over the years, through my investments in Breakthrough Energy and in other ways, I’ve heard about some potential breakthroughs that could be the revolution we need to get to zero emissions in electricity. These ideas are in various stages of development; some are relatively mature and well tested, while others are, frankly, nuts. But we can’t be afraid to bet on some crazy ideas. It’s the only way to guarantee at least a few breakthroughs.

Making Carbon-Free Electricity

Nuclear fission. Here’s the one-sentence case for nuclear power: It’s the only carbon-free energy source that can reliably deliver power day and night, through every season, almost anywhere on earth, that has been proven to work on a large scale.

No other clean energy source even comes close to what nuclear already provides today. (Here I mean nuclear fission—the process of getting energy by splitting atoms apart. I’ll get to its counterpart, nuclear fusion, in the next section.) The United States gets around 20 percent of its electricity from nuclear plants; France has the highest share in the world, getting 70 percent of its electricity from nuclear. Remember that by comparison solar and wind together provide about 7 percent worldwide.

And it’s hard to foresee a future where we decarbonize our power grid affordably without using more nuclear power. In 2018, researchers at the Massachusetts Institute of Technology analyzed nearly 1,000 scenarios for getting to zero in the United States; all the cheapest paths involved using a power source that’s clean and always available—that is, one like nuclear power. Without a source like that, getting to zero-carbon electricity would cost a lot more.

Nuclear plants are also number one when it comes to efficiently using materials like cement, steel, and glass. This chart shows you how much material it takes to generate a unit of electricity from various sources:

See how small the nuclear stack is? That means you’re getting far more energy for each pound of material that goes into building and running the power plant. It’s a major consideration, given all the greenhouse gases that are emitted when we produce those materials. (See the next chapter for more detail about that.) And these figures don’t take into account the fact that solar and wind farms generally need more land than nuclear plants, and they generate power only 25 to 40 percent of the time, versus 90 percent for nuclear. So the difference is even more dramatic than this chart shows.

It’s no secret that nuclear power has its problems. It’s very expensive to build today. Human error can cause accidents. Uranium, the fuel it uses, can be converted for use in weapons. The waste is dangerous and hard to store.

High-profile accidents at Three Mile Island in the United States, Chernobyl in the former U.S.S.R., and Fukushima in Japan put a spotlight on all these risks. There are real problems that led to those disasters, but instead of getting to work on solving those problems, we just stopped trying to advance the field.

Imagine if everyone had gotten together one day and said, “Hey, cars are killing people. They’re dangerous. Let’s stop driving and give up these automobiles.” That would’ve been ridiculous, of course. We did just the opposite: We used innovation to make cars safer. To keep people from flying through the windshield, we invented seat belts and air bags. To protect passengers during an accident, we created safer materials and better designs. To protect pedestrians in parking lots, we started installing rear-view cameras.

Nuclear power kills far, far fewer people than cars do. For that matter, it kills far fewer people than any fossil fuel.

Nevertheless, we should improve it, just as we did with cars, by analyzing the problems one by one and setting out to solve them with innovation.

Scientists and engineers have proposed various solutions. I’m very optimistic about the approach created by TerraPower, a company I founded in 2008, bringing together some of the best minds in nuclear physics and computer modeling to design a next-generation nuclear reactor.

Because no one was going to let us build experimental reactors in the real world, we set up a lab of supercomputers in Bellevue, Washington, where the team runs digital simulations of different reactor designs. We think we’ve created a model that solves all the key problems using a design called a traveling wave reactor.

TerraPower’s reactor could run on many different types of fuel, including the waste from other nuclear facilities. The reactor would produce far less waste than today’s plants, would be fully automated—eliminating the possibility of human error—and could be built underground, protecting it from attack. Finally, the design would be inherently safe, using some ingenious features to control the nuclear reaction; for example, the radioactive fuel is contained in pins that expand if they get too hot, which slows the nuclear reaction down and prevents overheating. Accidents would literally be prevented by the laws of physics.

We’re still years away from breaking ground on a new plant. So far, TerraPower’s design exists only in our supercomputers; we’re working with the U.S. government on building our first prototype.

Nuclear fusion. There’s another, entirely different approach to nuclear power that’s quite promising but still at least a decade away from supplying electricity to consumers. Instead of getting energy by splitting atoms apart, as fission does, it involves pushing them together, or fusing them.

Fusion relies on the same basic process that powers the sun. You start with a gas—most research focuses on certain types of hydrogen—and get it extraordinarily hot, well over 50 million degrees Celsius, while it’s in an electrically charged state known as plasma. At these temperatures, the particles are moving so fast that they hit each other and fuse together, just as the hydrogen atoms in the sun do. When the hydrogen particles fuse, they turn into helium, and in the process they release a great deal of energy, which can be used to generate electricity. (Scientists have various ways of containing the plasma; the most common methods use either powerful magnets or lasers.)

Although it’s still in the experimental phase, fusion holds a lot of promise. Because it would run on commonly available elements like hydrogen, the fuel would be cheap and plentiful. The main type of hydrogen that’s usually used in fusion can be extracted from seawater, and there’s enough of it to meet the world’s energy needs for many thousands of years. Fusion’s waste products would be radioactive for hundreds of years, versus hundreds of thousands for waste plutonium and other elements from fission, and at a much lower level—about as dangerous as radioactive hospital waste. There’s no chain reaction to run out of control, because the fusion ceases as soon as you stop supplying fuel or switch off the device that’s containing the plasma.

In practice, though, fusion is very hard to do. There’s an old joke among nuclear scientists: “Fusion is 40 years away, and it always will be.” (Admittedly, I’m using the term “joke” loosely.) One of the big hurdles is that it takes so much energy to kick off the fusion reaction that you often end up putting more into the process than you get out of it. And, as you might imagine given the temperatures involved, it’s also a huge engineering challenge to build a reactor. None of the existing fusion reactors are designed to produce electricity that consumers could use; they’re for research purposes only.

The biggest project currently under construction, a collaboration between six countries and the European Union, is an experimental facility in southern France known as ITER (pronounced like “eater”). Construction on the project began in 2010 and is still ongoing. By the mid-2020s, ITER is expected to generate its first plasma, and to generate excess power—10 times more than it needs to operate—in the late 2030s. That would be the Kitty Hawk moment for fusion, a major accomplishment that would put us on the path to building a commercial demonstration plant.

And there are more innovations coming that could make fusion more practical. For example, I know of companies that are using high-temperature superconductors to make much stronger magnetic fields for containing the plasma. If this approach works, it would allow us to make fusion reactors far smaller and therefore cheaper and more quickly too.

But the key point is not that any one company has the single breakthrough idea we need in nuclear fission or fusion. What’s most important is that the world get serious once again about advancing the field of nuclear energy. It’s just too promising to ignore.

Offshore wind. Putting wind turbines in an ocean or other body of water has various advantages. Because many major cities are near the coast, we can generate electricity much closer to the places where it’ll be used and not run into as many transmission problems. Offshore winds generally blow more steadily, so intermittency is less of an issue too.

Despite these advantages, offshore wind currently represents only a tiny share of the world’s total capacity for generating electricity—about 0.4 percent in 2019. Most of that is in Europe, particularly in the North Sea; the United States has just 30 megawatts installed, and that’s all in one project off the coast of Rhode Island. Remember that America uses around 1,000 gigawatts, so offshore wind provides roughly 1/32,000th of the country’s electricity.

For the offshore wind industry, there’s nowhere to go but up. Companies are finding ways to make turbines bigger so each one can generate more power, and they’re solving some of the engineering challenges involved in placing large metal objects out in the ocean. As these innovations drive down the price, countries are installing more turbines; the use of offshore wind has grown at an average annual rate of 25 percent in the past three years. The U.K. is the world’s biggest user of offshore wind today, thanks to clever government subsidies that encouraged companies to invest in it. China is making big investments in offshore wind and will likely be the world’s biggest consumer of it by 2030.

The United States has considerable offshore wind available, especially in New England, Northern California and Oregon, the Gulf Coast, and the Great Lakes; in theory, we could generate 2,000 gigawatts from it—more than enough to meet our current needs. But if we’re going to take advantage of this potential, we’ll have to make it easier to put up turbines. Today, getting a permit requires you to run a bureaucratic gauntlet: You buy one of a limited number of federal leases, then go through a multiyear process to generate an environmental impact statement, then get additional state and local permits. And at each step of the way, you may be opposed (rightly or not) by beachfront property owners, the tourism industry, fishermen, and environmental groups.

Offshore wind holds a lot of promise: It’s getting cheaper and can play a key role in helping many countries decarbonize.

Geothermal. Deep underground—as close as a few hundred feet, as far down as a mile—are hot rocks that can be used to generate carbon-free electricity. We can pump water at high pressure down into the rocks, where it absorbs the heat and then comes out another hole, where it turns a turbine or generates electricity some other way.

But exploiting the heat under our feet has its downsides. Its energy density—the amount of energy we get per square meter—is quite low. In his fantastic 2009 book, Sustainable Energy—Without the Hot Air, David MacKay estimated that geothermal could meet less than 2 percent of the U.K.’s energy needs, and delivering even that much would require exploiting every square meter of the country and doing the drilling for free.

We also have to dig wells to reach it, and it’s hard to know ahead of time whether any given well is going to produce the heat we need, or for how long. Some 40 percent of all wells dug for geothermal turn out to be duds. And geothermal is available only in certain places around the world; the best spots tend to be areas with above-average volcanic activity.

Although these problems mean that geothermal will contribute only modestly to the world’s power consumption, it’s still worth setting out to solve them one by one, just as we did with cars. Companies are working on various innovations that would build on the technical advances that have made oil and gas drilling so much more productive in the past few years. For example, some are developing advanced sensors that could make it easier to find promising geothermal wells. Others are using horizontal drills so they can tap these geothermal sources more safely and efficiently. It’s a great example of how technology that was originally developed for the fossil-fuel industry can actually help drive us toward zero emissions.

CHAPTER 4

HOW WE PLUG IN

27 percent of 51 billion tons per year

We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.

I wasn’t always aware of how much we rely on electricity, but over the years I’ve gradually come to see how essential it is. And I really appreciate what it takes to deliver this miracle. In fact, it’s fair to say that I’m in awe of all the physical infrastructure that makes electricity so cheap, available, and reliable. It’s downright magical that you can simply turn a switch almost anywhere in a well-off country and expect the lights to come on for a fraction of a penny. Literally: In the United States, leaving a 40-watt lightbulb turned on for an hour costs you about half of one cent.

I’m not the only one in the family who feels this way about electricity: My son, Rory, and I used to visit power plants for fun, just to learn how they worked.

After a family visit to the Þríhnúkagígur volcano in Iceland in 2015, Rory and I checked out the geothermal power plant next door.

I’m glad I’ve invested all that time learning about electricity. For one thing, it was a great father-son activity. (Seriously.) Besides, figuring out how to get all the benefits of cheap, reliable electricity without emitting greenhouse gases is the single most important thing we must do to avoid a climate disaster. That’s partly because producing electricity is a major contributor to climate change, and also because, if we get zero-carbon electricity, we can use it to help decarbonize lots of other activities, like how we get around and how we make things. The energy we give up by not using coal, natural gas, and oil has to come from somewhere, and mostly it will come from clean electricity. This is why I’m covering electricity first, even though manufacturing is responsible for more emissions.

Plus, even more people should be getting and using electricity. In sub-Saharan Africa, less than half of the population has reliable power at home. *1  And if you don’t have access to any electricity at all, even a seemingly simple task like recharging your mobile phone is difficult and expensive. You have to walk to a store and pay 25 cents or more to plug your phone into an outlet, hundreds of times more than people pay in developed countries.

860 million people don’t have reliable access to electricity. Fewer than half the people in sub-Saharan Africa are on the grid. (IEA)

I don’t expect most people to get as excited about grids and transformers as I do. (Even I can recognize that you have to be a pretty big nerd to write a sentence like “I’m in awe of physical infrastructure.”) But I think if everyone stopped to consider what it takes to deliver the service we now take for granted, they would appreciate it more. And they’d realize that none of us want to give it up. Whatever methods we use to get to zero-carbon electricity in the future will have to be as dependable and nearly as affordable as the ones we use today.

In this chapter I want to explain what it will take to keep getting all the things we like from electricity—a cheap source of energy that’s always available—and deliver it to even more people, but without the carbon emissions. The story starts with how we got here and where we’re headed.

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Considering how ubiquitous electricity is today, it’s easy to forget that it only became an important factor in most Americans’ lives a few decades into the 20th century. And one of our early major sources of electricity wasn’t any of the ones that we think of today, like coal, oil, or natural gas. It was water, in the form of hydropower.

Hydropower has a lot going for it—it’s relatively cheap—but it also has some big downsides. Making a reservoir displaces local communities and wildlife. When you cover land with water, if there’s a lot of carbon in the soil, the carbon eventually turns into methane and escapes into the atmosphere—which is why studies show that depending on where it’s built, a dam can actually be a worse emitter than coal for 50 to 100 years before it makes up for all the methane it’s responsible for. *2  In addition, the amount of electricity you can generate from a dam depends on the season, because you’re relying on rain-fed streams and rivers. And, of course, hydropower is immobile. You have to build the dams where the rivers are.

Fossil fuels don’t have that limitation. You can take coal, oil, or natural gas out of the ground and move it to a power plant, where you burn it, use the heat to boil water, and let the steam from the boiling water turn a turbine to make electricity.

Because of all these advantages, when demand for electricity in the United States took off after World War II, we met it with fossil fuels. They provided most of the new capacity we built in the second half of the 20th century—some 700 gigawatts, nearly 60 times more than we had installed before the war.

Getting all the world’s electricity from clean sources won’t be easy. Today, fossil fuels account for two-thirds of all electricity generated worldwide. (bp Statistical Review of World Energy 2020)

Over time, electricity has become extraordinarily cheap. One study found that it was at least 200 times more affordable in the year 2000 than in 1900. Today, the United States spends only 2 percent of its GDP on electricity, an amazingly low number when you consider how much we rely on it.

The main reason it’s so cheap is that fossil fuels are cheap. They’re widely available, and we’ve developed better and more efficient ways to extract them and turn them into electricity. Governments also go to considerable effort to keep the prices of fossil fuels low and encourage their production.

In the United States, we’ve been doing this since the earliest days of the Republic: Congress enacted America’s first protective tariff on imported coal in 1789. In the early 1800s, recognizing how important coal was for the railroad industry, states began to exempt it from some taxes and created other incentives for its production. After the corporate income tax was established in 1913, oil and gas producers got the right to deduct certain expenses, including drilling costs. In all, these tax expenditures represented roughly $42 billion (in today’s dollars) in support for coal and natural gas producers from 1950 through 1978, and they’re still in the tax code today. In addition, coal and gas producers benefit from favorable leasing terms on federal lands.

This flyer featuring a coal facility in Connellsville, Pennsylvania, dates from around 1900.

The United States isn’t alone. Most countries take various steps to keep fossil fuels cheap—the International Energy Agency (IEA) estimates that government subsidies for the consumption of fossil fuels amounted to $400 billion in 2018—which helps explain why they’re such a steady part of our electricity supply. The share of global power that comes from burning coal (roughly 40 percent) hasn’t changed in 30 years. Oil and natural gas together have been hovering around 26 percent for three decades. All told, fossil fuels provide two-thirds of the world’s electricity. Solar and wind, meanwhile, account for 7 percent.

As of mid-2019, some 236 gigawatts’ worth of coal plants were being built around the world; coal and natural gas are now the fuels of choice in developing countries, where demand has skyrocketed in the past few decades. Between 2000 and 2018, China tripled the amount of coal power it uses. That’s more capacity than in the United States, Mexico, and Canada combined!

Can we turn this around and get all the electricity we’ll need without any greenhouse gas emissions?

It depends on what you mean by “we.” The United States can get pretty close, with the right policies to expand wind and solar along with a big push for specific innovations. But can the whole world get zero-carbon electricity? That will be much harder.

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Let’s start with the Green Premiums for electricity in the United States. It’s actually good news: We can eliminate our emissions with only a modest Green Premium.

In the case of electricity, the premium is the additional cost of getting all our power from non-emitting sources, including wind, solar, nuclear power, and coal- and natural-gas-fired plants equipped with devices that capture the carbon they produce. (Remember that the goal isn’t to use only renewable sources like wind and solar; the goal is to get to zero emissions. That’s why I’m including these other zero-carbon options.)

How much is the premium? Changing America’s entire electricity system to zero-carbon sources would raise average retail rates by between 1.3 and 1.7 cents per kilowatt-hour, roughly 15 percent more than what most people pay now. That adds up to a Green Premium of $18 a month for the average home—pretty affordable for most people, though possibly not for low-income Americans, who already spend a tenth of their income on energy.

(You’re probably familiar with kilowatt-hours if you pay a utility bill, because they’re how we’re charged for electricity in our homes. But in case you’re wondering, a kilowatt-hour is a unit of energy that’s used to measure how much electricity you use in a given time period. If you consume one kilowatt for an hour, you’ve used one kilowatt-hour. The typical U.S. household uses 29 kilowatt-hours a day. On average, across all types of customers and states in the United States, a kilowatt-hour of electricity costs around 10 cents, though in some places it can be more than three times that much.)

It’s great that America’s Green Premium could be so low. Europe is similarly well situated; one study by a European trade association suggested that decarbonizing its power grid by 90 to 95 percent would cause average rates to go up about 20 percent. (This study used a different methodology from the way I figured America’s Green Premium.)

Unfortunately, few other countries are so lucky. The United States has a large supply of renewables, including hydropower in the Pacific Northwest, strong winds in the Midwest, and year-round solar power in the Southwest and California. Other countries might have some sun but no wind, or some wind but little year-round sun, or not much of either. And they might have low credit ratings that make it hard to finance big investments in new power plants.

Africa and Asia are in the toughest position. Over the past few decades, China has accomplished one of the greatest feats in history—lifting hundreds of millions of people out of poverty—and did it in part by building coal-fired electric plants very cheaply. Chinese firms drove down the cost of a coal plant by a remarkable 75 percent. And now they understandably want more customers, so they’re making a big play to attract the next wave of developing countries: India, Indonesia, Vietnam, Pakistan, and nations throughout Africa.

What will those potential new customers do? Will they build coal plants or go clean? Consider their goals and their options. Small-scale solar can be an option for people in poor, rural areas who need to charge their cell phones and run lights at night. But that kind of solution is never going to deliver the massive amounts of cheap, always-available electricity these countries need to jump-start their economies. They’re looking to do what China did: grow their economies by attracting industries like manufacturing and call centers—the types of businesses that demand far more (and far more reliable) power than small-scale renewables can provide today.

If these countries opt for coal plants, as China and every rich country did, it’ll be a disaster for the climate. But right now, that’s their most economical option.

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It’s not immediately obvious why there’s such a thing as a Green Premium in the first place. Natural gas plants have to keep buying fuel as long as they’re running; solar farms, wind farms, and dams get their fuel for free. Also, there’s the truism that as you take a technology to broad scale, it gets cheaper. So why does it cost extra to go green?

One problem is that fossil fuels are so cheap. Because their prices don’t factor in the true cost of climate change—the economic damage they inflict by making the planet warmer—it’s harder for clean energy sources to compete with them. And we’ve spent many decades building up a system to extract fossil fuels from the ground, get energy from them, and deliver that energy, all very cheaply.

Another reason is that, as I mentioned earlier, some regions of the world simply don’t have decent renewable resources. To get close to 100 percent, we’d have to move lots of clean energy from where it’s made (sunny places, ideally near the equator, and windy regions) to where it’s needed (cloudy, windless ones). That would require building new transmission lines, a costly and time-consuming task—especially if it involves crossing national borders—and the more power lines we install, the more the price of power goes up. In fact, transmission and distribution are responsible for more than a third of the final cost of electricity. *3  And many countries don’t want to rely on other countries for their electricity supply.

But cheap oil and expensive transmission lines aren’t the biggest drivers of the electricity Green Premium. The main culprits are our demand for reliability, and the curse of intermittency.

The sun and the wind are intermittent sources, meaning that they don’t generate electricity 24 hours a day, 365 days a year. But our need for power is not intermittent; we want it all the time. So if solar and wind represent a big part of our electricity mix and we want to avoid major outages, we’re going to need other options for when the sun isn’t shining and the wind isn’t blowing. Either we need to store excess electricity in batteries (which, I’ll argue in a moment, is prohibitively expensive), or we need to add other energy sources that use fossil fuels, such as natural gas plants that run only when you need them. Either way, the economics won’t work in our favor. As we approach 100 percent clean electricity, intermittency becomes a bigger and more expensive problem.

The clearest example of intermittency is when the sun goes down, cutting off our supply of solar-generated electricity. Suppose we want to solve that problem by taking one kilowatt-hour of excess electricity that’s generated during the day, storing it, and using it that night. (You’d need much more than that, but I’m picking one kilowatt-hour to make the math easy.) How much would that add to our electric bill?

That depends on two factors: how much the battery costs, and how long it’ll last before we have to replace it. For the cost, let’s say we can buy a one-kilowatt-hour battery for $100. (This is a conservative estimate, and I’ll ignore for the moment what happens if we have to take out a loan for this battery.) As for how long our battery will last, let’s assume it can go through 1,000 charge-and-discharge cycles.

So the capital cost of this one-kilowatt-hour battery will be $100 spread out over 1,000 cycles, which works out to 10 cents per kilowatt-hour. That’s on top of the cost of generating the power in the first place, which in the case of solar power is something like 5 cents per kilowatt-hour. In other words, the electricity we store for nighttime use will cost us triple what we’re paying during the day—5 cents to generate and 10 cents to store, for a total of 15 cents.

I know researchers who think they can make a battery that lasts five times longer than the one I’ve described here. They haven’t done it yet, but if they’re right, that would drive the premium down from 10 cents to 2 cents, a much more modest increase. In any case, the nighttime problem is solvable today, if you’re willing to pay a big premium, and with innovation I’m confident we can reduce that premium.

Unfortunately, nighttime intermittency isn’t the hardest problem to deal with. The seasonal variation between summer and winter is an even bigger hurdle. There are various ways to try to deal with it—like adding in power from a nuclear plant or a gas-fired electric plant fitted with a device that captures its emissions—and any realistic scenario will include these options. I’ll get to them later in the chapter, but for the sake of simplicity for now I’ll just use batteries to illustrate the problem of seasonal variation.

Say we want to store a single kilowatt-hour not for a day but for a whole season. We’ll generate it during the summer and use it in the winter to run a space heater. This time, the battery’s life cycle isn’t an issue, because we’re charging it only once a year.

But suppose we have to finance the purchase of the battery. Now we’ve tied up $100 in capital. (Obviously you wouldn’t finance a $100 battery, but you might need financing if you were buying enough to store several gigawatts. And the math is the same.) If we pay 5 percent interest on the capital, and the battery costs $100, that’s an additional $5 cost to store our single kilowatt-hour. And remember how much we’re paying for solar power during the day: just 5 cents. Who would pay $5 to store a nickel’s worth of electricity?

Seasonal intermittency and the high cost of storage cause yet another problem, especially for big users of solar power—the problem of overgeneration in the summer and undergeneration in the winter.

Because the earth is tilted on its axis, the amount of sunlight that hits any given part of the planet varies across the four seasons, as does the intensity of the sunlight. Just how big the variation is depends on how far you are from the equator. In Ecuador, there’s essentially no change. In the Seattle area, where I live, we get about twice as much sunlight on the longest day of the year as on the shortest day. Parts of Canada and Russia get about 12 times more. *4

To see why this variation matters, let’s do another thought experiment. Imagine there’s a town near Seattle—we’ll call it Suntown—that wants to generate a gigawatt of solar power year-round. How big should Suntown’s solar array be?

One option would be to install enough panels to produce a gigawatt during the summer, when sunlight is plentiful. But the town would be out of luck in the winter, when it’ll get only half as much sunlight. That’s undergeneration. (And the town council is well aware that storage is excessively expensive, so they’ve ruled out batteries.) On the other hand, Suntown could put up all the solar panels it needs for the short, dark days of winter, but then by the time summer arrives, it would be generating way more than necessary. Electricity would be so cheap that the town would be hard-pressed to recoup the expense of installing all those panels.

Suntown could deal with this overgeneration problem by turning off some of its panels during the summer, but then it’d be sinking money into equipment that gets used only for part of the year. That would raise the cost of electricity even more for every home and business in town; in other words, it would add to the town’s Green Premium.

The situation with Suntown isn’t merely a hypothetical example. Something similar has been happening in Germany, which through its ambitious Energiewende program set a goal of 60 percent renewables by 2050. The country has spent billions of dollars over the past decade expanding its use of renewables, increasing its solar capacity nearly 650 percent between 2008 and 2010. But Germany produced about 10 times more solar in June 2018 than it did in December 2018. In fact, at times during the summer, Germany’s solar and wind plants generate so much electricity that the country can’t use it all. When that happens, it ends up transmitting some of the excess to neighboring Poland and the Czech Republic, whose leaders have complained that it’s straining their own power grids and causing unpredictable swings in the cost of electricity.

There’s another problem caused by intermittency, and it’s even harder to solve than the daily or seasonal variety. What happens when an extreme event forces a city to survive several days without any renewable energy at all?

Imagine a future where Tokyo gets all its electricity from wind power alone. (Japan does, in fact, have quite a bit of onshore and offshore wind available.) One August, at the peak of cyclone season, a massive storm hits. The winds are so strong that they will rip the city’s wind turbines apart if they aren’t shut down. Tokyo’s leaders decide to switch off the turbines and get by solely on electricity stored up in the best large-scale batteries they can find.

Here’s the question: How many batteries would they need in order to power Tokyo for three days, until the storm passes and they can turn the turbines back on?

The answer is more than 14 million batteries. That’s more storage capacity than the world produces in a decade. Purchase price: $400 billion. Averaged over the lifetime of the batteries, that’s an annual expense of more than $27 billion. *5  And that’s just the capital cost of the batteries; it doesn’t include other expenses like installation and maintenance.

This example is entirely hypothetical. No one seriously thinks Tokyo should get all its electricity from wind or store all of it in today’s batteries. I’m using this illustration to make a crucial point: It’s extremely difficult and expensive to store electricity on a large scale, but that’s one of the things we’ll need to do if we’re going to rely on intermittent sources to provide a significant percentage of clean electricity in the coming years.

And we’re going to need much more clean electricity in the coming years. Most experts agree that as we electrify other carbon-intensive processes like making steel and running cars, the world’s electricity supply will need to double or even triple by 2050. And that doesn’t even account for population growth, or the fact that people will get richer and use more electricity. So the world will need much more than three times the electricity we generate now.

Because solar and wind are intermittent, our capacity to generate electricity will need to grow even more. (Capacity measures how much electricity we’re theoretically capable of producing when the sun is shining its brightest or the wind is blowing its hardest; generation is how much we actually get, after accounting for intermittency, shutting down power plants for maintenance, and other factors. Generation is always smaller than capacity, and in the case of variable sources like solar and wind it can be a lot smaller.)

With all the additional electricity we’ll be using, and assuming that wind and solar play a significant role, completely decarbonizing America’s power grid by 2050 will require adding around 75 gigawatts of capacity every year for the next 30 years.

Is that a lot? Over the past decade, we’ve added an average of 22 gigawatts a year. Now we need to install more than three times that much each year, and keep up the pace for the next three decades.

That will be a bit easier as we make solar panels and wind turbines cheaper and even more efficient—that is, as we invent ways to get even more energy from a given amount of sunlight or wind. (The best solar panels today convert less than a quarter of the sunlight that hits them into electricity, and the theoretical limit for the most common type of commercially available panels is about 33 percent.) As these conversion rates go up, we can get more power from the same amount of land, which will help as we deploy these technologies widely.

But more efficient panels and turbines aren’t enough, because there’s a major difference between the build-out America did in the 20th century and what we need to do in the 21st. Location is going to matter more than ever.

Since the beginning of the electric grid, utilities have placed most power plants close to America’s rapidly growing cities, because it was relatively easy to use railroads and pipelines to ship fossil fuels from wherever they were extracted to the power plants where they’d be burned to make electricity. As a result, America’s power grid relies on railroads and pipelines to move fuels over long distances to power plants, and then on transmission lines to move electricity over short distances to the cities that need it.

That model doesn’t work with solar and wind. You can’t ship sunlight in a railcar to some power plant; it has to be converted to electricity on the spot. But most of America’s sunlight supply is in the Southwest, and most of our wind is in the Great Plains, far from many major urban areas.

In short, intermittency is the main force that pushes the cost up as we get closer to all zero-carbon electricity. It’s why cities that are trying to go green still supplement solar and wind with other ways to generate electricity, such as gas-fired power plants that can be powered up and down as needed to meet demand, and these so-called peakers are not zero-carbon by any stretch of the imagination.

Just to be clear: Variable energy sources like solar and wind can play a substantial role in getting us to zero. In fact, we need them to. We should be deploying renewables quickly wherever it’s economical to do so. It’s amazing how much the costs of solar and wind power have dropped in the past decade: Solar cells, for example, got almost 10 times cheaper between 2010 and 2020, and the price of a full solar system went down by 11 percent in 2019 alone. A lot of the credit for these decreases goes to learning by doing—the simple fact that the more times we make some product, the better we get at it.

We do need to remove the barriers that keep us from making the most of renewable sources. For example, it’s natural to think of America’s electric grid as one single connected network, but in reality it’s nothing of the sort. There isn’t one power grid; there are many, and they’re a patchwork mess that makes it essentially impossible to send electricity beyond the region where it’s made. Arizona can sell spare solar power to its neighbors, but not to a state on the other side of the country.

We could solve this problem by crisscrossing the country with thousands of miles of special long-distance power lines carrying what’s called high-voltage current. This technology already exists; in fact, the United States already has some of these lines installed. (The biggest one runs from Washington State to California.) But the political hurdles to a massive upgrade of our electric grid are considerable.

Just think about how many landowners, utility companies, and local and state governments you’d need to bring together to build power lines that could move solar energy from the Southwest all the way to customers in New England. Merely picking the routes and establishing rights-of-way would be a massive undertaking; people tend to object when you want to run a big power line through the local park.

Construction on the TransWest Express, a transmission project designed to move wind-generated power from Wyoming to California and the Southwest, is scheduled to begin in 2021. The project is supposed to become operational in 2024—some 17 years after planning began.

But if we could pull this off, it would be transformative. I’m funding a project that involves building a computer model of all the power grids covering the United States. Using the model, experts have studied what it would take for all western states to reach California’s goal of 60 percent renewables by 2030, and for all eastern states to reach New York’s goal of 70 percent clean energy by that same year. What they found is that there’s simply no way for the states to do it without enhancing the power grid. The model also showed that regional and national approaches to transmission—rather than leaving each state to its own devices—would allow every state to meet the emission-reduction goals with 30 percent fewer renewables than they would need otherwise. In other words, we’ll save money by building renewables in the best locations, building a unified national grid, and shipping zero-emissions electrons wherever they’re needed. *6

In the coming years, as electricity becomes an even bigger part of our overall energy diet, we’ll need models like these for grids around the world. They’ll help us answer questions like: Which mix of clean energy sources will be the most efficient in a given place? Where should transmission lines go? Which regulations stand in the way, and what incentives do we need to create? I hope to see a lot more projects like this one.

Here’s another complication: As our houses rely less on fossil fuels and more on electricity (for example, to power electric cars and stay warm in the winter), we’ll need to upgrade the electrical service to each household—by at least a factor of two, and in many cases even more than that. A lot of streets will need to be dug up and electrical poles climbed to install heavier wires, transformers, and other equipment. So it will be felt in a real way by nearly every community, and the political impact will get down to the local level.

Technology might be able to help overcome some of the political barriers involved with these upgrades. For example, power lines are less of an eyesore if they’re run underground. But today, burying power lines increases the cost by a factor of 5 to 10. (The problem is heat: Power lines get hot when there’s electricity running through them. That’s no problem when they’re aboveground—the heat just dissipates into the air—but underground there’s no place for the heat to go. If the temperature gets too high, the power lines melt.) Some companies are working on next-generation transmission that would eliminate the heat problem and reduce the cost of underground lines significantly.

Deploying today’s renewables and improving transmission couldn’t be more important. If we don’t upgrade our grid significantly and instead make each region do this on its own, the Green Premium might not be 15 to 30 percent; it could be 100 percent or more. Unless we use large amounts of nuclear energy (which I’ll get to in the next section), every path to zero in the United States will require us to install as much wind and solar power as we can build and find room for. It’s hard to say exactly how much of America’s electricity will come from renewables in the end, but what we do know is that between now and 2050 we have to build them much faster—on the order of 5 to 10 times faster—than we’re doing right now.

And remember that most countries aren’t as lucky as the United States when it comes to solar and wind resources. The fact that we can hope to generate a large percentage of our power from renewables is the exception rather than the rule. That’s why, even as we deploy, deploy, deploy solar and wind, the world is going to need some new clean electricity inventions too.

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There’s already a lot of great research going on. If there’s one thing I love about my work, it’s the opportunity to meet with, and learn from, top scientists and entrepreneurs. Over the years, through my investments in Breakthrough Energy and in other ways, I’ve heard about some potential breakthroughs that could be the revolution we need to get to zero emissions in electricity. These ideas are in various stages of development; some are relatively mature and well tested, while others are, frankly, nuts. But we can’t be afraid to bet on some crazy ideas. It’s the only way to guarantee at least a few breakthroughs.

Making Carbon-Free Electricity

Nuclear fission. Here’s the one-sentence case for nuclear power: It’s the only carbon-free energy source that can reliably deliver power day and night, through every season, almost anywhere on earth, that has been proven to work on a large scale.

No other clean energy source even comes close to what nuclear already provides today. (Here I mean nuclear fission—the process of getting energy by splitting atoms apart. I’ll get to its counterpart, nuclear fusion, in the next section.) The United States gets around 20 percent of its electricity from nuclear plants; France has the highest share in the world, getting 70 percent of its electricity from nuclear. Remember that by comparison solar and wind together provide about 7 percent worldwide.

And it’s hard to foresee a future where we decarbonize our power grid affordably without using more nuclear power. In 2018, researchers at the Massachusetts Institute of Technology analyzed nearly 1,000 scenarios for getting to zero in the United States; all the cheapest paths involved using a power source that’s clean and always available—that is, one like nuclear power. Without a source like that, getting to zero-carbon electricity would cost a lot more.

Nuclear plants are also number one when it comes to efficiently using materials like cement, steel, and glass. This chart shows you how much material it takes to generate a unit of electricity from various sources:

How much stuff does it take to build and run a power plant? That depends on the type of plant. Nuclear is the most efficient, using much less material per unit of electricity generated than other sources do. (U.S. Department of Energy)

See how small the nuclear stack is? That means you’re getting far more energy for each pound of material that goes into building and running the power plant. It’s a major consideration, given all the greenhouse gases that are emitted when we produce those materials. (See the next chapter for more detail about that.) And these figures don’t take into account the fact that solar and wind farms generally need more land than nuclear plants, and they generate power only 25 to 40 percent of the time, versus 90 percent for nuclear. So the difference is even more dramatic than this chart shows.

It’s no secret that nuclear power has its problems. It’s very expensive to build today. Human error can cause accidents. Uranium, the fuel it uses, can be converted for use in weapons. The waste is dangerous and hard to store.

High-profile accidents at Three Mile Island in the United States, Chernobyl in the former U.S.S.R., and Fukushima in Japan put a spotlight on all these risks. There are real problems that led to those disasters, but instead of getting to work on solving those problems, we just stopped trying to advance the field.

Imagine if everyone had gotten together one day and said, “Hey, cars are killing people. They’re dangerous. Let’s stop driving and give up these automobiles.” That would’ve been ridiculous, of course. We did just the opposite: We used innovation to make cars safer. To keep people from flying through the windshield, we invented seat belts and air bags. To protect passengers during an accident, we created safer materials and better designs. To protect pedestrians in parking lots, we started installing rear-view cameras.

Nuclear power kills far, far fewer people than cars do. For that matter, it kills far fewer people than any fossil fuel.

Nevertheless, we should improve it, just as we did with cars, by analyzing the problems one by one and setting out to solve them with innovation.

Scientists and engineers have proposed various solutions. I’m very optimistic about the approach created by TerraPower, a company I founded in 2008, bringing together some of the best minds in nuclear physics and computer modeling to design a next-generation nuclear reactor.

Because no one was going to let us build experimental reactors in the real world, we set up a lab of supercomputers in Bellevue, Washington, where the team runs digital simulations of different reactor designs. We think we’ve created a model that solves all the key problems using a design called a traveling wave reactor.

Is nuclear power dangerous? Not if you’re counting the number of deaths caused per unit of electricity, as this chart shows. The numbers here cover the entire process of generating energy, from extracting fuels to turning them into electricity, as well as the environmental problems they cause, such as air pollution. (Our World in Data)

TerraPower’s reactor could run on many different types of fuel, including the waste from other nuclear facilities. The reactor would produce far less waste than today’s plants, would be fully automated—eliminating the possibility of human error—and could be built underground, protecting it from attack. Finally, the design would be inherently safe, using some ingenious features to control the nuclear reaction; for example, the radioactive fuel is contained in pins that expand if they get too hot, which slows the nuclear reaction down and prevents overheating. Accidents would literally be prevented by the laws of physics.

We’re still years away from breaking ground on a new plant. So far, TerraPower’s design exists only in our supercomputers; we’re working with the U.S. government on building our first prototype.

Nuclear fusion. There’s another, entirely different approach to nuclear power that’s quite promising but still at least a decade away from supplying electricity to consumers. Instead of getting energy by splitting atoms apart, as fission does, it involves pushing them together, or fusing them.

Fusion relies on the same basic process that powers the sun. You start with a gas—most research focuses on certain types of hydrogen—and get it extraordinarily hot, well over 50 million degrees Celsius, while it’s in an electrically charged state known as plasma. At these temperatures, the particles are moving so fast that they hit each other and fuse together, just as the hydrogen atoms in the sun do. When the hydrogen particles fuse, they turn into helium, and in the process they release a great deal of energy, which can be used to generate electricity. (Scientists have various ways of containing the plasma; the most common methods use either powerful magnets or lasers.)

Although it’s still in the experimental phase, fusion holds a lot of promise. Because it would run on commonly available elements like hydrogen, the fuel would be cheap and plentiful. The main type of hydrogen that’s usually used in fusion can be extracted from seawater, and there’s enough of it to meet the world’s energy needs for many thousands of years. Fusion’s waste products would be radioactive for hundreds of years, versus hundreds of thousands for waste plutonium and other elements from fission, and at a much lower level—about as dangerous as radioactive hospital waste. There’s no chain reaction to run out of control, because the fusion ceases as soon as you stop supplying fuel or switch off the device that’s containing the plasma.

In practice, though, fusion is very hard to do. There’s an old joke among nuclear scientists: “Fusion is 40 years away, and it always will be.” (Admittedly, I’m using the term “joke” loosely.) One of the big hurdles is that it takes so much energy to kick off the fusion reaction that you often end up putting more into the process than you get out of it. And, as you might imagine given the temperatures involved, it’s also a huge engineering challenge to build a reactor. None of the existing fusion reactors are designed to produce electricity that consumers could use; they’re for research purposes only.

The biggest project currently under construction, a collaboration between six countries and the European Union, is an experimental facility in southern France known as ITER (pronounced like “eater”). Construction on the project began in 2010 and is still ongoing. By the mid-2020s, ITER is expected to generate its first plasma, and to generate excess power—10 times more than it needs to operate—in the late 2030s. That would be the Kitty Hawk moment for fusion, a major accomplishment that would put us on the path to building a commercial demonstration plant.

And there are more innovations coming that could make fusion more practical. For example, I know of companies that are using high-temperature superconductors to make much stronger magnetic fields for containing the plasma. If this approach works, it would allow us to make fusion reactors far smaller and therefore cheaper and more quickly too.

But the key point is not that any one company has the single breakthrough idea we need in nuclear fission or fusion. What’s most important is that the world get serious once again about advancing the field of nuclear energy. It’s just too promising to ignore.

Offshore wind. Putting wind turbines in an ocean or other body of water has various advantages. Because many major cities are near the coast, we can generate electricity much closer to the places where it’ll be used and not run into as many transmission problems. Offshore winds generally blow more steadily, so intermittency is less of an issue too.

Despite these advantages, offshore wind currently represents only a tiny share of the world’s total capacity for generating electricity—about 0.4 percent in 2019. Most of that is in Europe, particularly in the North Sea; the United States has just 30 megawatts installed, and that’s all in one project off the coast of Rhode Island. Remember that America uses around 1,000 gigawatts, so offshore wind provides roughly 1/32,000th of the country’s electricity.

For the offshore wind industry, there’s nowhere to go but up. Companies are finding ways to make turbines bigger so each one can generate more power, and they’re solving some of the engineering challenges involved in placing large metal objects out in the ocean. As these innovations drive down the price, countries are installing more turbines; the use of offshore wind has grown at an average annual rate of 25 percent in the past three years. The U.K. is the world’s biggest user of offshore wind today, thanks to clever government subsidies that encouraged companies to invest in it. China is making big investments in offshore wind and will likely be the world’s biggest consumer of it by 2030.

The United States has considerable offshore wind available, especially in New England, Northern California and Oregon, the Gulf Coast, and the Great Lakes; in theory, we could generate 2,000 gigawatts from it—more than enough to meet our current needs. But if we’re going to take advantage of this potential, we’ll have to make it easier to put up turbines. Today, getting a permit requires you to run a bureaucratic gauntlet: You buy one of a limited number of federal leases, then go through a multiyear process to generate an environmental impact statement, then get additional state and local permits. And at each step of the way, you may be opposed (rightly or not) by beachfront property owners, the tourism industry, fishermen, and environmental groups.

Offshore wind holds a lot of promise: It’s getting cheaper and can play a key role in helping many countries decarbonize.

Geothermal. Deep underground—as close as a few hundred feet, as far down as a mile—are hot rocks that can be used to generate carbon-free electricity. We can pump water at high pressure down into the rocks, where it absorbs the heat and then comes out another hole, where it turns a turbine or generates electricity some other way.

But exploiting the heat under our feet has its downsides. Its energy density—the amount of energy we get per square meter—is quite low. In his fantastic 2009 book, Sustainable Energy—Without the Hot Air, David MacKay estimated that geothermal could meet less than 2 percent of the U.K.’s energy needs, and delivering even that much would require exploiting every square meter of the country and doing the drilling for free.

We also have to dig wells to reach it, and it’s hard to know ahead of time whether any given well is going to produce the heat we need, or for how long. Some 40 percent of all wells dug for geothermal turn out to be duds. And geothermal is available only in certain places around the world; the best spots tend to be areas with above-average volcanic activity.

Although these problems mean that geothermal will contribute only modestly to the world’s power consumption, it’s still worth setting out to solve them one by one, just as we did with cars. Companies are working on various innovations that would build on the technical advances that have made oil and gas drilling so much more productive in the past few years. For example, some are developing advanced sensors that could make it easier to find promising geothermal wells. Others are using horizontal drills so they can tap these geothermal sources more safely and efficiently. It’s a great example of how technology that was originally developed for the fossil-fuel industry can actually help drive us toward zero emissions.

Storing Electricity

Batteries. I’ve spent way more time learning about batteries than I ever would’ve imagined. (I’ve also lost more money on start-up battery companies than I ever imagined.) To my surprise, despite all the limitations of lithium-ion batteries—the ones that power your laptop and mobile phone—it’s hard to improve on them. Inventors have studied all the metals we could use in batteries, and it seems unlikely that there are materials that will make for vastly better batteries than the ones we’re already building. I think we can improve them by a factor of 3, but not by a factor of 50.

Still, you can’t keep a good inventor down. I’ve met some brilliant engineers working on affordable batteries that could store enough energy for a city—what we call grid-scale batteries, as opposed to the smaller ones that run a phone or computer—and hold it long enough to get through seasonal intermittency. One inventor I admire is working on a battery that uses liquid metals instead of the solid metals employed in traditional batteries. The idea is that liquid metal lets you store and deliver much more energy very quickly—exactly the kind of thing you need when you’re trying to power an entire city. The technology has been proven in a lab, and now the team is trying to make it cheap enough to be economical and prove that it works in the field.

Others are working on something called flow batteries, which involve storing fluids in separate tanks and then generating electricity by pumping the fluids together. The bigger the tanks, the more energy you can store, and the bigger the battery, the more economical it becomes.

Pumped hydro. This is a method of storing city-sized amounts of energy, and it works like this: When electricity is cheap (for example, when a stiff wind is turning your turbines really fast), you pump water up a hill into a reservoir; then, when demand for power goes up, you let the water flow back down the hill, using it to spin a turbine and generate more electricity.

Pumped hydro is the biggest form of grid-scale electricity storage in the world. Unfortunately, that’s not saying much. The 10 largest facilities in the United States can store less than an hour’s worth of the country’s electricity consumption. You can probably guess why it hasn’t really taken off: To pump water up a hill, you need a big reservoir of water and, of course, a hill. Without either, you’re out of luck.

Several companies are working on alternatives. One is looking at whether you could move something other than water uphill—pebbles, for example. Another is working on a process that would do away with the hill but not the water: You pump water underground, keep it there under pressure, and then release it when you’re ready to turn a turbine. If this approach works, it would be magical, because there would be very little aboveground equipment to worry about.

Thermal storage. The notion here is that when electricity is cheap, you use it to heat up some material. Then, when you need more electricity, you use the heat to generate power via a heat engine. This can work at 50 or 60 percent efficiency, which isn’t bad. Engineers know about many materials that can stay hot for a long time without losing much energy; the most promising approach, which some scientists and companies are working on, is to store the heat in molten salt.

At TerraPower, we’re trying to figure out how to use molten salt so that (if we’re able to build a plant) we don’t have to compete with solar-generated electricity during the day. The idea would be to store heat generated during the day, then convert it to electricity at night, when cheap solar power isn’t available.

Cheap hydrogen. I hope we get some big breakthroughs in storage. But it’s also possible that some innovation will come along and make all these ideas obsolete, the way the personal computer came along and more or less made the typewriter unnecessary.

Cheap hydrogen could do that for storing electricity.

The reason is that hydrogen serves as a key ingredient in fuel cell batteries. Fuel cells get their energy from a chemical reaction between two gases—usually hydrogen and oxygen—and their only by-product is water. We could use electricity from a solar or wind farm to create hydrogen, store the hydrogen as compressed gas or in another form, and then put it in a fuel cell to generate electricity on demand. In effect, we’d be using clean electricity to create a carbon-free fuel that could be stored for years and turned back into electricity at a moment’s notice. And we would solve the location problem I mentioned earlier; although you can’t ship sunlight in a railcar, you can turn it into fuel first and then ship it any way you like.

Here’s the problem: Right now, it’s expensive to produce hydrogen without emitting carbon. It’s not as efficient as storing the electricity directly in a battery, because first you have to use electricity to make hydrogen and then later you use that hydrogen to make electricity. Taking all these steps means you lose energy along the way.

Hydrogen is also a very lightweight gas, which makes it hard to store within a reasonably sized container. It’s easier to store the gas if you pressurize it (you can squeeze more into the same-volume container), but because hydrogen molecules are so small, when they’re under pressure, they can actually migrate through metals. It’s as if your gas tank slowly leaked gas as you filled up.

Finally, the process of making hydrogen (called electrolysis) also requires various materials (known as electrolyzers) that are quite costly. In California, where cars that run on fuel cells are now available, the cost of hydrogen is equivalent to paying $5.60 a gallon for gasoline. So scientists are experimenting with cheaper materials that could serve as electrolyzers.

Other Innovations

Capturing carbon. We could keep making electricity as we do now, with natural gas and coal, but suck up the carbon dioxide before it hits the atmosphere. That’s called carbon capture and storage, and it involves installing special devices at fossil-fuel plants to absorb emissions. These “point capture” devices have existed for decades, but they’re expensive to buy and operate, they generally capture only 90 percent of the greenhouse gases involved, and power companies don’t gain anything from installing them. So very few are in use. Smart public policies could create incentives to use carbon capture, a subject we’ll return to in chapters 10 and 11.

Earlier, I mentioned a related technology called direct air capture. It involves exactly what the name implies: capturing carbon directly from the air. DAC is more flexible than point capture, because you can do it anywhere. And in all likelihood, it’ll be a crucial part of getting to zero; one study by the National Academy of Sciences found that we’ll need to be removing about 10 billion tons of carbon dioxide a year by mid-century and about 20 billion by the end of the century.

But DAC is a much bigger technical challenge than point capture, thanks to the low concentration of carbon dioxide in the air. When emissions come directly out of a coal plant, they’re highly concentrated, in the range of 10 percent carbon dioxide, but once they’re in the atmosphere, where DAC operates, they disperse widely. Pick one molecule at random out of the atmosphere and the odds that it will be carbon dioxide are just 1 in 2,500.

Companies are working on new materials that are better at absorbing carbon dioxide, which will make both point capture and DAC cheaper and more effective. In addition, today’s approaches to DAC require a lot of energy to trap the greenhouse gases, collect them, and store them safely. There’s no way to do all that work without using some energy; the laws of physics set a minimum amount on how much will be required. But the latest technology uses much more than that minimum, so there’s a lot of room for improvement.

Using less. I used to scoff at the notion that using power more efficiently would make a dent in climate change. My rationale: If you have limited resources to reduce emissions (and we do), then you’d get the biggest impact by moving to zero emissions rather than by spending a lot trying to reduce the demand for energy.

I haven’t abandoned that view entirely, but I did soften it when I realized just how much land it will take to generate lots more electricity from solar and wind. A solar farm needs between 5 and 50 times more land to generate as much electricity as an equivalent coal-powered plant, and a wind farm needs 10 times more than solar. We should do everything we can to increase the odds that we can scale up to 100 percent clean power, and that will be easier if we reduce electricity demand wherever we can. Anything that reduces the scale we need to reach is helpful.

There’s also a related approach called load shifting or demand shifting, which involves using power more consistently throughout the day. If we did it on a large scale, load shifting would represent a pretty big change in the way we think about powering our lives. Right now, we tend to generate power when we use it—for example, cranking up electric plants to run a city’s lights at night. With load shifting, though, we do the opposite: We use more electricity when it’s cheapest to generate.

For example, your water heater might be able to switch on at 4:00 p.m., when power is less in demand, instead of 7:00 p.m. Or you could plug in your electric vehicle when you get home for the day, and it would automatically wait to charge itself until 4:00 a.m., when electricity is cheap because so few people are using it. On an industrial level, energy-intensive processes like treating wastewater and making hydrogen fuels could be done at a time of day when power is easiest to come by.

If load shifting is going to have a significant impact, we’ll need some changes in policy as well as some technological advances. Utility companies will have to update the price of electricity throughout the day to account for shifts in supply and demand, for instance, and your water heater and electric car will have to be smart enough to take advantage of this price information and respond accordingly. And in extreme cases, when electricity is especially hard to come by, we should have the ability to shed demand, meaning we’d ration electricity, prioritize the highest needs (say, hospitals), and shut down nonessential activities.

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Keep in mind that although we need to pursue all these ideas, we probably don’t need all of them to pan out in order to decarbonize our power grid. Some of the ideas overlap each other. If we get a breakthrough in cheap hydrogen, for example, we might not need to worry as much about getting a magic battery.

What I can say for certain is that we need a concrete plan to develop new power grids that provide affordable zero-carbon electricity reliably, whenever we need it. If a genie offered me one wish, a single breakthrough in just one activity that drives climate change, I’d pick making electricity: It’s going to play a big role in decarbonizing other parts of the physical economy. I’ll turn to the first of these—how we make things like steel and cement—in the next chapter.