Power Diversity
By Sable Riley and Michael Leitman
America’s appetite for energy never takes a break—and neither can the power grid. That reliability stems from a diverse energy mix. Across the country, electric utilities depend on coal, natural gas, nuclear, wind, solar, hydropower, biomass—from organic waste like wood chips—and geothermal sources to keep the power flowing.
Energy Mix by the Numbers
According to the U.S. Energy Information Administration, natural gas is the leading source of energy, generating about 43% of the United States’ electricity in 2023, the most recent statistics available.
Coal, once dominant, has fallen to about 16%. Nuclear produces roughly 18%, delivering reliable baseload power. Renewables continue to grow. Wind contributes about 10%, hydroelectric dams about 6%, solar farms 4%, and biomass and geothermal together account for 1–2%.
Altogether, renewables make up just more than 20% of the mix. This balance—60% fossil fuels, 20% nuclear and 20% renewables—leverages the strengths of each resource.
Electric utilities embrace an all-of-the-above strategy. Jim Matheson, CEO of the National Rural Electric Cooperative Association, says diversity of electric generation, including baseload sources, is essential to providing dependable, affordable power.
Utilities use what’s local and available—hydro in the Northwest and solar in the Southwest—and exchange power regionally to stay flexible.
Dispatchable and Nondispatchable Sources
Some sources can be turned on when needed; others can’t. Dispatchable sources like natural gas, coal and hydropower—if those resources are available—ramp up and down on command, responding instantly to demand changes. In contrast, nondispatchable sources like wind and solar depend on weather. A reliable grid needs both types working in concert. On a sunny afternoon, solar farms may flood California’s grid with power. At sunset, fast-start gas and hydroelectric plants take over.
“The growth of renewables has had many benefits, but the wind doesn’t always blow, and the sun doesn’t always shine,” Southwest Power Pool’s Paul Suskie said in a 2023 congressional testimony on grid security.
Grid operators must rely on other fuel sources to ensure demand can still be met, Paul said. Real-world events underscore this interplay.
During California’s 2022 heat wave, battery storage systems and gas plants met peak evening demand after solar generation declined. Conversely, Winter Storm Elliott in December 2022 caused blackouts in parts of the Southeast when more than 100,000 megawatts of coal and gas capacity failed during freezing conditions. That crisis revealed the risk of over-reliance on a single resource.
Policymaking and Grid Reliability
Electricity demand is also skyrocketing, fueled by new data centers and a surge in domestic manufacturing.
According to the North American Electric Reliability Corp., electric demand growth is now the highest it has been in more than two decades. Over the next 10 years, peak power needs are expected to rise by more than 18%, with new projects driving demand even higher. That puts grid reliability under the microscope.
Regulators at the Federal Energy Regulatory Commission and at the state level are adjusting policies to support capacity, storage and demand response. In 2024, FERC Commissioner Mark Christie warned the United States is heading for a catastrophic situation in terms of reliability if changes aren’t made carefully during testimony before the House Subcommittee on Energy, Climate, and Grid Security.
The nation’s energy mix is shifting, driven by economics, innovation and policy choices. Federal incentives from the 2022 Inflation Reduction Act accelerated investments in solar, wind, batteries and advanced nuclear. At the same time, environmental regulations are prompting closures of older coal and gas plants.
NERC’s 2024 assessment cautions that rising demand combined with shrinking baseload capacity puts many regions at risk of shortfalls during extreme conditions—even after recent solar and storage additions.
Strengthening Renewables
Energy storage is a promising development. Batteries help balance intermittent renewables by storing surplus energy and releasing it when needed. Battery capacity in the United States jumped 66% in 2024 to roughly 26 gigawatts and could nearly double again by the end of 2025, according to the U.S. Energy Information Administration.
The Bottom Line
No single energy source can guarantee affordable, uninterrupted electricity across a country as vast and weather-diverse as the United States. Natural gas is flexible but susceptible to supply disruptions. Coal and nuclear plants offer consistent output but are less adaptable and aging. Wind and solar, while clean, depend on weather, and storage solutions remain limited.
Having a range of energy resources safeguards against any one fuel becoming scarce, expensive or unexpectedly unavailable. That’s why electric utilities continue to invest in a balanced portfolio of energy sources—diversity gives the grid the resilience it needs to meet demand in the moments that matter most.