Another solar farm is coming to the California desert. The buyers: cities near the coast.

Sammy Roth | Palm Springs Desert Sun

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The year-round sunshine that scorches the open desert east of Palm Springs will help three Southern California cities meet their renewable energy needs starting in 2020 — and some of the electricity will be stored in giant batteries for use after dark.

A developer is preparing to build two solar farms, Desert Harvest and Palen, on several thousand acres of federal land between Joshua Tree National Park and Interstate 10, near an existing solar facility. Some of the electricity will be sold through a unique arrangement that involves Burbank and Vernon in Los Angeles County and Anaheim in Orange County, under the terms of a 25-year contract announced last month.

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Solar has boomed in California in recent years due to falling costs, and the 25-year contract is yet another indication that many local governments and utility companies now consider solar power an affordable, reliable energy source. The contract could also be a preview of the solar industry's future.

The developer of the two desert projects, San Diego-based EDF Renewable Energy, plans to build a large battery facility to store solar power for use when the sun goes down — and while this is one of the first big solar contracts with an energy storage component, it almost certainly won't be the last.

Traditionally, one of solar power's biggest shortcomings was that it only worked when the sun was shining. In the past, there wasn't enough solar power on the grid for that to matter. But California now has so much solar power on the grid — solar accounted for more than 10 percent of the state's electricity last year — that the daytime/nighttime issue is starting to become a problem. Some afternoons, the state's solar facilities generate more electricity than Californians need, sending energy prices into negative territory. Then in the evening, when people go home and start to use electricity, utilities largely replace the disappearing solar power with polluting natural gas plants.

Energy storage could help solve the problem, especially as the cost of lithium-ion batteries continues to plunge and power companies get better at utilizing the technology.

None of the four big solar farms currently operating in California's Riverside County have energy storage, but the next few probably will. In addition to EDF's Desert Harvest and Palen projects, the developer Recurrent Energy has proposed a battery for its Crimson solar farm that would be the world's largest. The Desert Quartzite solar facility, which is being developed by First Solar on 5,100 acres of public land near the Arizona border, would also have an energy storage component, according to environmental documents published Thursday by the federal Bureau of Land Management.

The energy storage market is still in its infancy, and EDF's solar-plus-storage contract is uniquely structured, according to Ravi Manghani, director of energy storage at GTM Research, a clean-tech consulting firm. The three cities involved in the transaction — Anaheim, Burbank and Vernon — will pay a stable long-term price for the credits they need to meet the state's renewable energy mandate. EDF, meanwhile, will actually sell the energy from one of its solar projects on the wholesale market, placing the risk of fluctuating market prices on the developer. EDF will be able to operate the batteries for its own benefit, possibly by charging them during the middle of the day, when energy prices are low or negative, then selling the stored electricity on the wholesale market during the evening, giving utility companies a cheaper, cleaner option than natural gas.

"We don't actually touch the electricity itself," said Lincoln Bleveans, assistant general manager for power supply at Burbank Water and Power. "We pay for it, we pay the developer of the project to generate it, and then they sell it for us in the broader power markets in a way that doesn't create risk for us."

"We are really just buying the renewable energy credits from the project," he added.

Manghani referred to the Desert Harvest contract as "version 2.0 of solar plus storage."

"We've already started to see a lot happen (with storage) in Nevada, Arizona, Colorado, now California. In a matter of time we’ll see that happen in other states," Manghani said.

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The contract was negotiated by the Southern California Public Power Authority, or SCPPA, a consortium of public power agencies. Anaheim will pay for 36 megawatts of solar power, Burbank will pay for 22 megawatts and Vernon will pay for 12 megawatts. EDF says the batteries will have a capacity of 35 megawatts over a four-hour lifespan.

The developer hasn't decided what type of battery technology to use, but lithium-ion batteries are a possibility, according to EDF executive Ian Black. He said a lot of companies are trying to work out the best contract structure for solar-plus-storage deals.

"I imagine there are more customers who will see what SCPPA's doing, and will look at them as a leader in the space and will look at something similar to that," Black said.

EDF is also under contract to sell as much as 150 megawatts of solar power from the company's two desert solar projects to Marin Clean Energy, a Bay Area power provider with more than 250,000 customers. The Desert Harvest project will cover 1,200 acres of federal land and have a capacity of 150 megawatts. Palen will cover 3,100 acres of federal land and have a capacity of 500 megawatts. In addition to the Marin and SCPPA deals, EDF will sell 125 megawatts of Palen's output to Southern California Edison.

Black said EDF will determine this year whether to use Desert Harvest or Palen to fulfill the SCPPA contract. Electricity sales under that contract will begin in late 2020.

While Desert Harvest has been relatively noncontroversial, Palen has caused an uproar from some conservationists and Native American groups, who have argued the facility would disrupt the sand-dune habitat of Mojave fringe-toed lizards, desert kit foxes and other species, and destroy ancient tribal artifacts and sacred sites. Federal officials indicated earlier this year that they are likely to approve Palen despite those concerns.

Anaheim expects to pay $1.8 million annually as part of the EDF contract. Vernon expects to pay $600,000 annually. A figure for Burbank wasn't immediately available.

Sammy Roth writes about energy and the environment for The Desert Sun. He can be reached at sammy.roth@desertsun.com, (760) 778-4622 and @Sammy_Roth.