“But what happens when the wind doesn’t blow or the sun doesn’t shine?”
The short answer: grid operators continue doing what they’ve always done: balance changes in supply and demand, with a more reliable electric grid resulting because of renewable energy.
The U.S. has over 53,000 wind turbines spread across 41 states, adding crucial diversity to the country’s electricity mix. That’s important, because relying on any single source of generation presents risks. For example, during 2014’s Polar Vortex, 22 percent of Great Lakes and Mid-Atlantic conventional power plants failed because of the extreme cold. However, wind turbines kept reliably turning, keeping the lights on for American families and businesses.
The reality is the people who manage the country’s electric grid already incorporate large amount of renewable energy onto their systems.
Wind makes up an important part of America’s electricity mix
Iowa, South Dakota and Kansas all generate 30 percent or more of their electricity using wind. Warren Buffet’s MidAmerican Energy expects to be 90 percent wind-powered in the near future, and in Colorado, Xcel Energy runs on 20 percent renewables. The Southwest Power Pool (SPP), grid manager across 14 Midwestern states, gets nearly a fifth of its electricity from wind year round, and has been over 50 percent wind-powered at times.
“Ten years ago we thought hitting even a 25 percent wind-penetration level would be extremely challenging, and any more than that would pose serious threats to reliability,” said Bruce Rew, vice president of operations for SPP. “Now we have the ability to reliably manage greater than 50 percent. It’s not even our ceiling.”
Other studies by experts support SPP’s findings.
PJM, the country’s largest grid operator, recently found it could handle over 75 percent wind power reliably. Meanwhile, Department of Energy researchers have found renewables can provide between 25 and 50 percent of America’s electricity with no concerns on any measure of reliability, and no new technology beyond more transmission lines.
Wind and solar actually make the grid more reliable
Besides increasing the diversity of generation sources, wind and solar make the grid more reliable because of their advanced power electronics.
These fast-acting controls allow wind and solar plants to better withstand voltage and frequency disturbances, which can often shut down conventional power plants. In fact, it was a frequency disturbance that knocked out power across the Washington, D.C. region in 2015. Adding more wind and solar to the grid helps smooth out these sorts of fluctuations and lets the system recover faster.
AWEA, the Solar Energy Industries Association, the American Council on Renewable Energy, and the Advanced Energy Economy sent research on these issues to DOE in response to the agency’s ongoing review of the country’s electric grid. AWEA’s materials can be accessed here: