An Oklahoma electric cooperative has decided to build a power plant combining wind, solar, and battery technology instead of a natural gas plant to handle peak energy needs. The primary reason? Money.

"It's actually cheaper economically than a gas peaker plant of similar size, particularly with the tax credits that are available right now," said Phillip Schaeffer, the co-op's principal resource planning engineer. "Prices have fallen significantly over the last several years."

Western Farmers Electric Cooperative of Anadarko, Oklahoma, announced the Skeleton Creek project last week. It's the largest proposed solar-wind-battery plant in the US. It will include facilities in Garfield, Alfalfa, and Major counties in north central Oklahoma:

  • Skeleton Creek Wind, a previously announced venture that will provide 250 megawatts of wind energy. It's scheduled to begin operating by the end of this year.
  • Skeleton Creek Solar, providing 250 MW of solar energy. It's to start operating by the end of 2023.
  • Skeleton Creek Storage, providing 200 MW of battery storage for 4 hours (i.e., 800 megawatt-hours). It's also scheduled to begin operations by the end of 2023.

Western Farmers provides electricity to 21 member cooperatives and other power users, including Altus Air Force Base near Altus, Oklahoma. Its service area is primarily in Oklahoma and New Mexico, although it extends into parts of Texas and Kansas.

A subsidiary of NextEra Energy Resources of Juno Beach, Florida, will build and operate the plant. NextEra is a wholesale electricity supplier and the world's largest operator of wind and solar projects.

"At Western Farmers, we are always looking for ways to better serve our customers with reliable, low-cost, and environmentally friendly energy," said CEO Gary Roulet, quoted in a Western Farmers news release.

"With the price of wind and solar energy lower than ever, we are now able to pair it with battery storage to make more affordable, renewable energy available to customers for more hours of the day—even when the wind isn't blowing and the sun isn't shining."

To understand why the wind-solar-battery combination makes sense, you have to understand why Western Farmers is building more generating capacity.

The co-op needs to add 400 megawatts of capacity by 2025 to fulfill its resource adequacy obligation, Schaeffer told Greentech Media. The company is required to have enough generating capacity to handle its expected 2025 peak load plus a little extra in case of unexpectedly heavy demand.

Power companies generally operate two main types of power plants. "Baseload" plants (usually coal, nuclear, or hydroelectric) run pretty much continuously, supplying the base amount of power that a grid needs at its minimum load.

Western Farmers needed to add a plant in the other category: a "peaking" or "peaker" plant. At times of low demand, peakers (usually natural gas plants) sit idle. When power demand is high, such as during hot summer afternoons, they fire up to supply the needed additional electricity.

The Skeleton Creek wind turbines and solar panels should between them provide at least some energy every day. Solar panels produce power even on cloudy days, and Oklahoma ranks 9th among states in potential wind power, according to the US Department of Energy's National Renewable Energy Laboratory.

Primarily, though, Western Farmers is counting on the facility for peak power. The battery storage will kick in during peak demand periods and also when it's necessary to smooth out the inherently intermittent nature of solar and wind generation.

A battery can respond to demand fluctuations faster than a natural gas plant. And it provides a bonus that a fossil-fuel peaker can't: A battery can store excess energy generated during nonpeak times and release that stored power when it's needed. In essence, a battery can time-shift energy production.

Western Farmers has considerable experience with renewable energy. It started buying wind power in 2003 and has used solar energy for several years.

"People in rural communities want the right thing done for their community as well," Schaeffer said. "They want to make sure it's the right thing to do economically, and they liked the aspect of the environmental consciousness."