The lower-carbon future of coal-fired power plants
Conversion to natural gas
In the 1980’s, horizontal drilling and fracking had become common practice. Natural gas prices plummeted. Those lower costs, and the reduced carbon dioxide emissions of natural gas, caused many coal-fired power plants to be converted to natural gas. Power plant owners minimized transition costs, using the existing power grid without having to modify it.[1]
More than 30 years later, the trend away from coal as energy source has continued. As of September 2021, the 252 coal-fired plants operating in the United States were producing 212 GW of electricity.[2] That output is expected to be diminished 28% by 2035.[3]
Conversion to renewables
With lower, 21st-century costs of solar and wind power devices, renewable sources have become bottom-line solid, carbon-free options. The numbers are significant. Today’s estimates have those sources generating 55% of the U.S. power mix by 2035. Fifteen years later, up to 2,000 gigawatts of renewable energy could be deployed. That would be 70%–80% of U.S. electricity production.[4]
A significant challenge remains: intermittency. When the sun sets or is obscured by clouds, buildings still must have HVAC. When the wind stops blowing, traffic lights must still operate. Power is needed 24 x 365 and must not be intermittent. Fortunately, there are several ways to achieve long-duration energy storage.
Long-duration energy storage
Power plants that once burned coal can now store long-duration renewable energy. Several technologies are being tested. A few have already been deployed. Each year, greater numbers of coal-fired plants are being converted.[5]
- Lithium-ion cells
This well-known type of storage is relatively expensive. - Nickel-hydrogen batteries
This heavier alternative to lithium-ion operates in extreme heat and cold. It is well-suited for grid-scale storage. - Iron-air batteries
Using a process first documented in the 1970’s, iron becomes rust, then rust is converted back into iron. This discharges and charges a battery.[6] - Gravity-based kinetics
This combining of ancient and 21st-century technologies uses renewable power to raise massive blocks of bricks. The blocks are lowered, producing kinetic energy as needed to run generators. - Pumped heat energy
Heat can be stored in molten salt. Chilled liquid will retain cold. The available technology of heat engines uses temperature differences to generate electricity. - Compressed air
During hours when renewable energy is abundant, air can be pressurized then stored in tanks or subterranean caverns.
Is your community or utility company considering alternatives to coal-fired power? ecoPreserve is here to help with planning, presenting alternatives, and finding sources of funding.
[1] EIA.gov — U.S. Energy Information Agency
[2] Statista.com
[3] PowerMag.com — Long-Duration Energy Storage: A Strategy for Retiring Coal Plants?
[4] NREL.gov — National Renewable Energy Laboratory (U.S. Department of Energy)
[5] GreenTechMedia.com
[6] Phys.org — Phys.org is part of the Science X website network.
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