EECS4460.223.23.21.pptx
Power System Management
EECS 4460/5460-901
Lecture #22
New Technologies and the Future Utility
Large Scale Storage
1
Large-scale electricity storage is perhaps our greatest opportunity for cost and efficiency improvements in power generation
The need is obvious – electricity on demand
The load factor varies from 40-60% seasonally and daily
Technologies in use, others being developed
Flywheels
Thermal energy storage (TES)
Pumped Hydroelectric (PHS)
Compressed Air Energy Storage (CAES)
Batteries (Advanced Battery Energy Storage – ABES)
All involve energy conversion of some sort…
Utilities and Large-Scale Storage
Classification of Storage Technologies
State of Development*
*University of Michigan Center for Sustainable Systems
Storage Applications and Scale
Total Storage in the U.S. as of September 2020: 37.5GW of 1100GW Total
Graph adapted from the DOE website, “DOE Global Energy Storage Database,” Energy Storage Exchange, www.energystorageexchange.org.
Areas of Storage Applications
Electric Supply
-Electric energy time-shift -Generating capacity
Ancillary Services
-Load following -Area regulation
-Reserve capacity -Voltage support
Grid Operations
-Transmission support -Congestion relief
-T&D upgrade deferral -Substation onsite power
End User/Utility Customer
Power quality -Demand charge management
Service reliability -Time-of-use cost management
Renewables Integration
-Time shift -Capacity firming
-Wind generation integration
Storage Options May Be Locational
Accelerating a rotor (flywheel) to a very high speed, maintaining rotational (kinetic) energy
Motor and generator in vacuum system reduces friction and energy loss
Magnetic bearings reduce friction
Carbon-fiber composites have higher tensile strength than steel
Very low maintenance costs; long life span; emission friendly
Good for frequency regulation and balancing
Energy Storage Flywheels
S
20MW in Hazle Township PA
Simplified Flywheel
In general, heat or cool a storage medium to be used later
Medium is pumped heat (e.g. inert gas or air) or liquid (e.g. liquid nitrogen)
Heat the medium during off-peak periods (or from solar collector)
Release: heat pump becomes heat engine which drives generator
Wide variety of configurations
Thermal Energy Storage
Basic “Reversable Heat Pump” e.g. argon gas
Energy from the sun heats the ocean, especially the surface water
Warm surface water pumped through an evaporator containing a working fluid. The vaporized fluid drives the turbine generator.
Vaporized fluid turned back to liquid in condenser cooled with cold water pumped from deeper in the ocean
Ocean Thermal Energy Conversion (OTEC)
Experimental operational OTEC system
using seawater as working fluid. Off the
coast of Hawaii. Output: 250 kilowatts
Pump water from low to high reservoirs, releases when electricity is needed – generating electrical energy from kinetic energy
Long-lived assets (50-60 years); Efficiencies 70-85%
96% of global energy storage is from PHS
Pumped Hydroelectric Storage (PHS)
Ludington, MI
Six units, 1872 MW total
New turbines, +40 years
Seneca – Warren PA
451MW Unit
Owned by LS Power
Simplified Example of Pumped Hydro Storage Plant
Plant net capability is 1280MWhr (after losses)
Reservoir operates at 80% efficiency (1600MWhr are consumed and 1280MWhr are produced)
At $15/MWhr off–peak marginal price, it costs $24,000 to fill the reservoir during off-peak periods. Water can be pumped to the upper reservoir (1600MWhr x $15/MWhr)
Power is sold the following day on-peak at $40/MWHr, revenues are $40/MWhr x 1280MWhr = $51,200
Gross profit is $27,200 ($51,200-$24,000)
Money can be Made with Storage
Capture and store compressed air in cavern; heat the pressurized air and inject it into an expansion turbine. Compress air off-peak.
With gas turbine, 40-60% CO2 emission reduction, 42-55% plant efficiencies
Two plants worldwide; Germany @ 320MW and U.S. @ 110MW.
Compressed Air Energy Storage (CAES)
McIntosh, AL
110MW
Since 1991
Germany
Compressed Air Energy Storage
Stored as chemical energy converted back to electrical energy
Several variations among U.S. projects: lead-acid, lithium-ion, sodium-based, and flow batteries.
U.S. large scale installations total about 870 (mid-2019) with efficiencies between 60-95%
Nearly 40% is in PJM, but it is changing with market design changes. Most are owned by Independent Power Producers providing frequency regulation services.
Since 2013, California legislation has mandated ever-increasing battery capacity, currently approaching 4000MW
San Diego 30MW lithium battery in 2017 to mitigate Aliso Canyon Gas supply concerns in California
BESS includes enclosures for thermal management, inverter/charger, switchgear, transformer, metering, software controller
Battery Energy Storage Systems (BESS)
Grid-Level Battery Applications
| Technology comparison for Grid-Level applications | ||||||
| Technology | Moving Parts | Operation at Room Temperature | Flammable | Toxic Materials | In production | Rare metals |
| Vanadium flow[43] | Yes | Yes | No | Yes | Yes | No |
| Liquid Metal | No | No | Yes | No | No | No |
| Sodium-Ion | No | No | Yes | No | No | No |
| Lead-Acid[44] | No | Yes | No | Yes | Yes | No |
| Sodium-sulfur batteries | No | No | No | Yes | Yes | No |
| Ni-Cd | No | Yes | No | Yes | Yes | Yes |
| Al-ion | No | Yes | No | No | No | No |
| Li-ion | No | Yes | Yes | No | Yes | No |
Battery Applications Vary on the Grid
Growth in Large Scale Battery Systems
Large-Scale Battery Installations by Region
Activity driven by regional needs and market designs
Batteries in PJM are Primarily Used for Frequency Regulation; Batteries in CAISO Cover Multiple Uses*
*2018 data
Providing Flexible Ramping on a 3MW Feeder
Recent Study Results on Grid Frequency Response
Source: NERC Energy Storage, February 2021
Study case: 9.4GW (26%) reduction of
spinning reserve +
7.8GW (23.5%) reduction of
frequency response reserve
Base case: Largest N-2 case, loss of
two Palo Verde units
Large-Scale Battery Capacity by Chemistry
Ion Flow in the Lithium-Ion Battery
Electricity drives a chemical reaction while charging, then it reverses the reaction to release electricity when discharging
Source: NERC Energy Storage, February 2021
Lithium-Ion Battery Comparisons
Source: NERC Energy Storage, February 2021
Flow Batteries
“Advertised” benefits:
Modular and scalable
Lower cost
Readily available materials
Longer duration
Lower environmental impact
Two half cells separated by an ion exchange membrane
Electroactive materials are chemical compounds that reversibly undergo reduction and oxidation
For example, vanadium/vanadium or zinc/bromine
Flow Battery Comparisons
Source: NERC Energy Storage, February 2021
Battery Ratings
Nameplate Power Capacity is in MW
Nameplate Energy Capacity is in MWhrs (convert from Ahr)
Nameplate duration is in hours
Example: A 6MW power capacity battery has a 24MWhr
energy capacity, its nameplate duration is 4 hours.
Usable capacity may be less depending on discharge cycles
Battery Costs - Shorter duration less expensive on a per-unit capacity basis - Longer duration have lower costs on a per-unit of energy basis
Short: Less than 30 minutes
Medium: 30 minutes to 2 hours
Long: More than 2 hours nameplate duration
Implied Battery Costs are Declining
Costs are Projected to Decline*
*NERL Report, “Cost projections for Utility Scale Batteries”, June 2019
Planned Battery Storage Capacity Additions
Source: EIA Storage Workshop, July 2020
State Policy Correlates with Growth
Combined Renewable Plus Storage Projects
Comparison: Hydro Pumped Storage and Batteries
Large-scale energy storage has been with us for decades, dominated by pumped hydro storage
RTO/ISO’s are highly interested in large scale storage
FERC (2016) has offered new pricing models for RTO/ISOs, with further rulemaking planned
Costs and market pricing need further development
In 2018 global battery demand exceeded supply, driven by strong South Korea incentives
Global emphasis continues
Emerging battery materials supply chain challenges
Summary: Grid Scale Energy Storage
Time to Fix This
International Power Systems
Global Energy Picture
Environmental Update
Electricity Growth and Supply
Political and Policy Issues
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