In 2021, a record amount of utility-scale solar was installed in the U.S., and the proportion of solar and wind that fuels electricity quadrupled in the past 10 years. However, less than 10 percent of electricity is generated from wind and less than 3 percent from solar.
Electricity is generated by a variety of fuel sources — natural gas, coal, nuclear, hydroelectricity, wind and solar. This diverse mix is going through a major change. In the last decade, wind power has more than tripled, from generating 100 billion kilowatt-hours (kWh) of electricity to 378 billion kWh, and solar energy has climbed from nearly zero to 115 billion kWh.
Those increases still leave renewable energy’s share of electricity generation far behind natural gas at 1,579 billion kWh, coal at nearly 900 billion kWh, and nuclear at nearly 800 billion kWh. Fossil fuels still generate most of our electricity, but the fuel mix is being reshaped by the decline of coal and the rise of renewables.
In the 1990s, coal generated more than half the electricity in the U.S. Then natural gas supplies soared because of fracking, driving prices to 10-year lows. In addition, environmental concerns put pressure on coal.
While coal and natural gas generation produce greenhouse gases, natural gas produces less. Power suppliers began running efficient natural gas plants more and building new ones as many coal plants were run less or retired. Today, natural gas produces 38 percent of our electricity compared with coal’s 22 percent — less than half of what it was 30 years ago.
The rise of solar and wind means more than adding sources to the electricity fuel mix. Today, 80 percent of electricity is generated by heating water that turns a turbine. Coal and natural gas are burned, and even nuclear power works by heating water.
Those heat-based sources can run 24/7 and adjust output as demand fluctuates. Solar and wind only work when the sun shines and the wind blows. As those intermittent sources become a bigger share of how electricity is generated, utilities are developing ways to coordinate the flow of the energy sources.
Renewable energy is predicted to be the fastest growing electricity fuel for the next 25 years. A more diverse fuel mix calls for new approaches to the most basic function of electric utilities — keeping the lights on.