Striving to keep California's power system well balanced while transitioning to larger volumes of variable wind and solar resources, a coalition of local government-run energy suppliers in the central and northern parts of the state on Oct. 16 issued a joint request for proposals for 500 MW of long-duration energy storage.
"We are technology agnostic and we are looking to the bidders to put forth their best offer that meets the criteria that we need," Peninsula Clean Energy CEO Jan Pepper said in an interview. Peninsula Clean Energy is one of eight community choice aggregators, or CCAs, seeking projects at least 50 MW in size with a minimum of eight hours of discharge capacity to come online by 2026, at the latest, under 10-year contracts.
Other participants include Central Coast Community Energy, CleanPowerSF, MCE Clean Energy, Redwood Coast Energy Authority, Silicon Valley Clean Energy, San Jose Clean Energy and Sonoma Clean Power. With a combined peak load of 5,395 MW, the CCAs together are responsible for purchasing power for roughly 2.3 million customers. PG&E Corp. subsidiary Pacific Gas and Electric Co. continues to deliver the power the CCAs procure.
The request comes after California in mid-August experienced its first rolling power outages in two decades, which California ISO officials and state regulators have attributed to an intense "climate change-induced" heatwave and poor planning. The state's review of its approach to grid reliability is likely to result in additional energy storage purchases to help fill a capacity gap, especially in the early evening hours when more than 20,000 MW of solar power drops offline toward sunset.
While the CCAs already planned their long-duration storage request months earlier, the blackouts "highlighted how the grid needs to respond as there are more extreme weather events with climate change," Pepper said.
Seeking 24/7 renewable energy
Developers of long-duration storage systems have expressed significant interest in advance, responding with 58 project proposals involving 14 technologies to an initial request for information the CCAs issued in June. Potential technology types include lithium-ion batteries, flow batteries, pumped hydroelectric storage, compressed air, cryogenic energy storage and hydrogen.
Official bids to the formal request are due Dec. 1, with tentative contract approvals set for July 2021.
For Peninsula Clean Energy, which serves San Mateo County, south of San Francisco, long-duration storage could unlock its ambitions to completely decarbonize its power portfolio by 2025, 20 years ahead of a statewide target.
"We have the goal of providing 100% renewable energy on a 24/7 basis by 2025, so we're trying to match our load to our supply every hour of every day," Pepper said. "Long-duration storage is going to be one of the components that we'll need. We'll also probably need some kind of seasonal storage technology."