“What happens when the wind doesn’t blow or the sun doesn’t shine?”
That’s a common question from those wanting to understand how grid operators integrate renewable energy.
Fortunately, the experts who keep the lights on every day find they can reliably handle large amounts of wind and solar energy.
Grid operators have always balanced major shifts in supply and demand. Factories, air conditioners and appliances turn on and off in waves, varying by time of day and season. Major spikes occur from events as simple as halftime during a football game, when millions of refrigerator doors open.
Large coal, gas, and nuclear power plants can also break down unexpectedly, suddenly removing significant amounts of electricity from the system.
Meanwhile, spread across 41 states, the output of America’s 53,000 utility-scale wind turbines stays relatively constant. Changes are slow and predictable based on weather forecasting, and are mostly canceled out by far greater variations in demand and other supply.
It’s generally more expensive for grid operators to accommodate the abrupt loss of a large conventional generator, because that requires keeping fast-acting backup resources “spinning” 24/7.
A prime example occurred during 2014’s Polar Vortex weather event. The bitter cold and loss of gas supply forced many conventional power plants to shut down abruptly. At the same time, high demand for home heating sent natural gas prices and electricity prices skyrocketing. However, wind turbines kept reliably generating electricity, saving Great Lakes and Mid-Atlantic consumers over $1 billion in two days.
The U.S. has enough installed wind power to supply the equivalent of 25 million homes. So utilities and grid operators have already had ample opportunity to figure out how to integrate wind energy.
Xcel Energy’s Colorado Balancing Authority already runs on 20 percent renewable energy. ERCOT in Texas got 15 percent of its electricity from wind in 2016. The Southwest Power Pool (SPP), grid manager across parts of 14 states, is nearing 20 percent wind year-round — and just peaked at 54 percent wind earlier this year. PJM, the country’s largest grid operator, recently found it could handle over 75 percent wind power reliably.
“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, SPP’s vice president of operations. “Now we have the ability to reliably manage greater than 50 percent. It’s not even our ceiling.”
Wind power remains on track to supply 10 percent of U.S. electricity by 2020, adding diversity, security and reliability to our electric grid. The men and women keeping our lights on already know wind works, and by helping ensure the country’s grid stays secure, wind works for all Americans.