California Has Over 15,000 MW Of Energy Storage
It was approximately two years ago that I interviewed the California Energy Commission about the state of California having a little over 6,600 MW of energy storage online. New information has come out recently stating the total is now over 15,000 MW. Obviously, that is a huge amount and a great increase over a short time span.
For some context, Texas is no. 2 in energy storage among US states and has just under 10,000 MW. Now, some CleanTechnica readers will get irked at reading MW figures and no MWh, but various online sources don’t include the megawatt-hours.
California Energy Commission staff answered some questions for CleanTechnica and included a note about the duration below.
Usually, energy storage capacity includes the duration too. Is the 15,763 MW for 4 hours, or 63,052 MWh?
It would be the former – 15,763 MW for four hours. However, keep in mind that is an aggregated total that includes residential and commercial systems that typically run for two hours and are not dispatchable to the grid. So if you wanted to be precise, it would be the 13,248 MW of utility-scale energy that could discharge for four hours.
While energy capacity in battery storage is commonly expressed in terms of total energy stored—such as watt-hours or megawatt-hours—for statewide planning and grid reliability, the focus is often on peak power output measured in megawatts. This metric allows battery systems to be directly compared to traditional power generation units, which are also rated by their nameplate capacity in megawatts. By evaluating the instantaneous power batteries can deliver—typically over four hours—system operators can better understand how these resources contribute to grid stability during periods of high demand.
There has been a 1,944% increase since the start of the Newsom administration — up from 770 MW in 2019. What drove the great increase?
To achieve its goal of 100 percent clean energy by 2045, California has targets of adding 19,500 MW of battery storage to the grid by 2035 and a goal of 52,000 MW by 2045. Because of these targets (which inform energy procurement policies at the California Public Utilities Commission, which is where investor-owned utilities get direction on energy purchases) and the state’s efforts to speed the buildout of clean energy, California has become the second largest energy storage market in the world (behind China). Please see CEC Chair David Hochschild’s remarks on this at https://www.youtube.com/shorts/JI8A-VedEro. In addition:
Assembly Bill (AB) 2514 (Skinner, Chapter 469, Statutes of 2010), amended by Assembly Bill 2227 (Bradford, Chapter 606, Statutes of 2012), was designed to encourage California to incorporate energy storage into the electricity grid, as codified at Public Utilities Code § 2835-2839 and § 9506. https://www.energy.ca.gov/data-reports/reports/energy-storage-targets-publicly-owned-utilities
Assembly Bill 2514 also required the California Public Utilities Commission (CPUC) to open a proceeding to determine appropriate targets, if any, for the state’s investor-owned utilities to procure viable and cost-effective energy storage systems and, by October 1, 2013, to adopt an energy storage system procurement target, if determined to be appropriate, to be achieved by each load-serving entity by December 31, 2020. More information on that proceeding can be found on the CPUC’s web site.
California Public Utilities Code required each local publicly owned electric utility (POU):
- By March 1, 2012, the governing board of each POU must initiate a process to determine appropriate targets, if any, for the utility to procure viable and cost-effective energy storage systems by December 31, 2016, and a second target achieved by December 31, 2020.
- The governing board of each POU must adopt targets, if determined to be appropriate, by October 1, 2014.
Is the next milestone 20,000 MW for at least 4 hours, and if so, when might that be reached?
There is an interim goal laid out in the Governor’s energy transition plan of 19,500 MW by 2035 and a long-term goal of reaching 52,000 MW by 2045.
Is most of the energy storage lithium-ion batteries?
At this time, we do not have the chemical composition being reported to us by the utilities. A future rulemaking may address this aspect.
Is most of the energy storage paired with solar or wind power?
At this time, battery energy storage systems are predominantly co-located with solar PV systems. However, there are battery systems installed to support other technologies such as wind and natural gas along with stand-alone systems.
Will the energy storage capacity of all the EV batteries in CA ever be reflected in the total energy storage for the state?
Not at this time. The dashboard reflects stationary energy storage systems located within a utility’s distribution territory.
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