Energy stored in batteries is being sent in large volumes to California as record-breaking hot weather in the western US has put the state’s power sector in crisis.
The California Independent System Operator (CAISO), which manages the grid and oversees wholesale electricity markets for more than 80% of California, has been issuing “Flex Alerts” since August. CAISO activates the alerts to manage the shortfall of electricity supply versus demand, asking customers to reduce power use and bring in as much resources as they can to increase supply. For example, in mid-August, a Flex Alert marked the first time a network of 2,500 Tesla Powerwalls converged on a virtual power plant (VPP) in California utility Pacific Gas and Electric’s (IOU) service area. ( PG&E ), delivered up to 16.5 MW of stored solar energy to the grid. While in 2020, utilities instituted rolling blackouts in some areas to protect the grid, and last summer’s Flex Alerts were also activated, no one was under any illusion that margins could continue to be tight. State Gov. Gavin Newsom made moves to speed up the deployment of battery storage by cutting red tape as a state of emergency was declared last year.
CAISO said before the summer that it expected to have 4 GW of battery storage capacity available, mostly from four-hour grid-scale battery energy storage (BESS) systems, but it hasn’t gotten that far. However, it is believed to be close to that limit, especially with some large systems coming online in recent weeks, such as a pair of projects from AES Corporation totaling 227MW/908MWh. In recent days this fleet has been active to a large extent. On Sept. 6, Jill Anderson, executive vice president of operations at another major utility, Southern California Edison, tweeted that it was “incredible” to see battery storage hit “record after record of grid support during during this intense heat.” The most extreme mismatch between supply and demand generally occurs between 7 p.m. and 9 p.m., during the evening rush hour. Anderson posted a chart from CAISO showing that around 7 p.m. that day, over 3,000 MW of battery capacity was being discharged into the grid. “Just now we’ve seen batteries discharge more than double last year and orders of magnitude more than what was available on the grid in 2020,” Anderson tweeted.
The day before (September 5), CAISO “barely got by” without back-to-back blackouts and relied heavily on battery storage as well as more than 8 GW of imports, said Ryan Sweezey, principal analyst at Wood Mackenzie Power & Renewables . a LinkedIn post. The state may not always be able to rely on imports today or in the future, Sweezey said, “but storage is here to stay,” noting that while on Aug. 14, 2020, when rolling blackouts occurred, storage discharge between The two-hour evening peak window was just 50 MW, compared to about 2.5 GW in the same period on September 5, 2022.

California contribution is about to increase – and get smarter?

In fact, on CAISO’s “Today’s Outlook” page on its website, users can monitor the state of demand, supply, emissions and prices, looking at current situations as well as trends. It makes for compelling, if unapologetically nerdy, viewing. This shows that while the relative contribution of batteries may be small compared to renewables, large hydro, natural gas and imports from other states, their role as a dispatch resource is important in filling this gap. supply-demand. It’s not just large-scale batteries, as Tesla’s previous report showed. In 2021, smart energy storage and software provider Stem Inc said it dispatched more than 500 MWh of commercial and industrial customers’ battery systems enrolled in grid service programs during the June heatwave. Stem’s fleet is not only in California, but most of it is. In late August of this year, residential solar PV and energy storage installation and leasing company Sunrun sent media outlets, including Energy-Storage.news, a press release claiming to ship over 80MW of battery storage capacity from homes of customers in the CAISO network every day. That’s more than many fossil fuel plants in California and an increase of more than 60 percent from 2021, the company said. Despite the increasingly important role of batteries, there are still some inefficiencies in market design to solve that can help them contribute even more. Cody Hill, an engineer and senior vice president at energy storage developer and operator Rev Renewables, noted that one of Rev Renewables’ battery projects shipped at a time of day when day-ahead market caps rose above a threshold. But the most pressing need for power came later, when the 125 MW system was already discharged and unable to contribute, Hill wrote. An article for Volume 31 of our PV Tech Power magazine, published in the second quarter of this year, looked at the role large-scale battery storage is playing on the grid today, with reference to key areas of the battery storage market such as California’s CAISO , the Texas ERCOT grid, the United Kingdom and Ireland, Western Europe and Australia.