Assignment
iMozzie
EECS4460.79.5.19.pptx
Power System Management
EECS 4460/5460-901
Lecture #7
Power Generation Alternatives
1
Fundamentals in Power Generation – Electricity is a Secondary Source of Energy
Electricity from Direct Energy Conversion
Electricity Production from a Direct Source
Naturally replenishing but flow-limited energy resource
Virtually inexhaustible in duration but limited in terms of the amount of energy per unit of time
Examples: Hydro Plants, Solar Cells, Wind Turbines
Electricity from Thermal Energy Conversion
Electricity Production from the conversion of a heat source
Heat source is non renewable - fossil or nuclear fuel
Fuel is directly injected into a combustion turbine or into a boiler to create steam to rotate turbine/generator
Examples: Coal, Nuclear, Oil or Gas w/ Steam Turbines; Gas Turbine
Fundamentals in Power Generation
Hydro Generation
Coal Fired Generation
Nuclear Power Plants
Oil and Gas Fired Generation
Additional Renewable Generation
Wind Turbines
Solar Cells
Biomass Generation
Storage
Future Technologies
Fundamentals in Power Generation – Evolution
4
Hydro Power Generation
Relies on a successful
“water cycle”
Most dams were built for
flood control and irrigation
Higher flow results in more
energy
“Run-of-River” or reservoir
storage with dam
Seasonal and annual variations
Hydro Power Generation
Hydro Power Generation – U.S.
Hydropower Generation – U.S.
Water Supply Forecasting is Critical
(2019 example)
Hydro Power Generation
Largest Hydro Plant in the World is Three Gorges in China
22,500MW
32 x 700Mw Turbine Generators
2 x 50Mw Generators
Built 1993 -2012
$32B (USD)
Yangtze River
Displaced 1.3M
people
Hydro Power Summary
Advantages:
Renewable resource
No carbon emissions
Domestic source
Flood control, irrigation,
water supply
Reliable, responsive
Dispatchable
Low operating cost, simple
Disadvantages:
Environmental impact
on the land use
Impact on natural habitats
Impact on fish migration
Organic materials in reservoirs
release methane
Coal Fired Generation The Rankine Cycle
The “Ideal” Rankine Cycle
Goal:
Improve the Thermodynamic
Efficiency of the Process
Net Power Output
Per Heat Input
Coal Fired Generation
Today’s Coal Fired Power Plant
Supercritical Boilers
Higher pressure and temperature, water @ supercritical state
Air Preheaters
Preheats ambient air used for combustion processes
Feedwater Heaters
Heat exchanger that preheats the feedwater using turbine extraction steam through to Preheat Feedwater
Economizers
Heat exchanger that preheats feedwater using flue gas
Operations and Maintenance
Coal Quality, Adjust for Load Following, Internal Cleaning, Fix Leaks!
Improving Plant Efficiency
Heat Rate and “Conversion Efficiency”
Amount of heat input required per unit of power generated
Energy input in BTU/hr
Electricity in kw
Heat Rate in BTU/kwhr
The lower the heat rate, the more efficient the plant
Coal Fired Generation - Efficiency
Heat Rate and “Thermal Efficiency”
Approximately 3412 Btu/hr is equal to 1 kw
We can calculate plant thermal efficiency:
E.g. Heat rate @ 10,300 Btu/kwhr
Thermal efficiency = 3412/10,300 ~ 33%
(industry average)
Improving Heat Rate = Savings
Heat content of coal ranges from 8000 Btu/lb to 12,000 Btu/lb
Coal costs about $30/ton, or $1.5MMBtu to $2/MMBtu
Typical coal plant is 500Mwe and burns 6000 tons/day
An example of 1% improvement in heat rate:
500Mw plant at 80% capacity factor that burns $2/MMBtu coal
500Mw x 10,200 btu/kwhr x8760hrs x.8 x1.0% x$2/MMBtu = $700,000/year +
Plant designers and operators are focused
on heat rate improvement
Improving Heat Rate = Savings
Savings achieved at
$2.50/MMBtu
Also, in the example, a 1% heat rate deduction corresponds to a
1% reduction in CO2 emissions - about 40,000 tons/ year
And a corresponding reduction in NOx and SO2 and mercury.
Average Heat Rates
| 2007 BTU/Kwhr | 2017 BTU/Kwhr | |
| Coal – Steam Turbine | 10,158 | 10,043 |
| Oil – Steam Turbine | 10,398 | 10,199 |
| Gas – Steam Turbine | 10,440 | 10,353 |
| Nuclear – Steam Turbine | 10,489 | 10,459 |
| Gas – Simple Cycle | 11,632 | 11,176 |
| Gas – Combined Cycle | 7,577 | 7649 |
Source: EIA Form-860, August 2019
Coal Power Summary
Advantages:
Abundant fuel reserves
Low cost fuel
Known technology
Reliable, responsive
Dispatchable
Low capital & operating
costs
Repowering options
Disadvantages:
Carbon and other emissions
Impact from coal mining
Environmental impact
on the land use; mining and plant
Waste byproduct management
Cooling water impacts
Competitive challenge in markets
1950
1970
1990
2018
330
1,532
2,900
Billion KWH Generated
150
0
180
N/A
330
700
22
810
N/A
1,532
1,600
580
720
N/A
2,900
1,146
807
757
1,468
4,178
Coal
Nuclear
Other
Natural Gas
Billion KWH
4,178
Sources: http://www.eia.gov/cneaf/electricity/epm/table1_1.html, March 2011, EIA Electricity Data Browser net generation from electricity plants, updated 3/1/2019
55%
46%
45%
U.S. Generation has Grown 13-Fold Since 1950: Coal Percentage Significant until Lately …
East
Coal Nuclear Natural Gas Other 1146 807 1468 757
East Coal Other Nuclear 1600 720 580
East Coal Nuclear Other 700 22 810
East Coal Nuclear Other 150 0 180
Coal Generation over the Years
Coal Plant Retirements Continue
Coal Plant Retirements Continue
Coal and Natural Gas - “Head to Head”
25
