Diversity in Energy Generation and Storage
Big Gains in Energy Storage — Short-Term, Medium-Term, and Long-Term
Kern County has become the renewable energy hub of California and key to our state achieving its clean energy goals. Long a producer of power from wind, it has recently added large-scale solar projects. Although Kern County sends renewable energy all over the state, the bulk of this energy goes to L.A.’s homes and businesses. One farm, Eland, when fully online, will produce 7 percent of the Los Angeles Department of Water and Power’s (DWP) electricity. Eland would not be remarkable if only a solar farm, but it is linked with lithium-ion battery storage banks — 172 Tesla megapacks, capable of delivering 300 megawatts for peak use after sunset.
Lithium-ion batteries are good for short-term storage, up to four hours, but not good for longer periods of cloudy, low-wind days when the sun and wind are unable to generate electricity. Building enough battery storage to fully cover 24 hours a day, 365 days a year would require exorbitant amounts of money, leading to higher energy bills. Consequently, the strategy is to invest in diversity: a mix of geothermal, hydropower, more distant wind farms, and even some nuclear power. The DWP is building a new, gas-fired plant that will use some green hydrogen in lieu of natural gas, with the goal of eventually shifting to 100 percent hydrogen. Green hydrogen is a clean fuel made from water and renewable energy.
Longer-term storage is mainly being done using mountain reservoirs operating as “pumped storage” where excess solar or wind energy pumps water uphill to the higher reservoir. When power is needed, water can be released to run downhill, turning turbines and generating electricity. It is collected at the lower lake, ready to repeat the cycle. The DWP uses the Castaic and Pyramid lakes for “pumped storage.”
For intermediate storage, around 12 hours, flow batteries are gaining adoption. The water from tanks containing liquid electrolytes is pumped through electrode membranes to extract electrons. Compared with lithium-ion batteries they currently cost more, require more space, and are less portable. On the other hand, they are safer and have unlimited cycling life. Lithium batteries are good for about 7,000 cycles.
Although L.A.’s DWP has a sordid history, it is forging a new story as a climate leader and with record-low electrical rates, far lower than Southern California Edison’s rates. It is targeting 98 percent climate-friendly electricity in six years and 100 percent by 2035, a decade earlier than the state’s same goal.
Even being only half operational at present, Eland has been performing superbly and is optimizing the use of wind and solar generation to fit demand. When fully online, Eland will get L.A. to 64 percent clean energy. Planners are facilitating the permitting process for energy developers by steering them away from federal public lands, areas close to homes, and prime wildlife habitat. Kern County benefits by gaining good-paying construction jobs and per-acre payments from developers that fund government services.
