California’s Electric Grid
California has set a goal to reach 100% carbon-free electricity by 2045. The state is making progress - as of 2022, about 37% of California’s energy mix comes from natural gas and about 54% comes from non greenhouse gas emitting and renewable resources (Figure 1). Of the current renewable energy sources, about 17% comes from solar and 11% from wind.
On some very sunny days, California produces more solar energy than we can use during the day. Right now, that will often result in some of that extra energy going to waste. However, Californians use the most energy on summer days in the late afternoon and just after the sun goes down, typically between 4 and 9 PM. This is the period we refer to as “peak demand.” During that window of time, we currently rely heavily on gas plants. By storing excess solar energy produced during the day, we can help reach peak demand using clean energy. Right now, the best tool we have to store renewable energy is batteries.
Figure 1: Data from the California Energy Commission’s “2022 Total System Electric Generation”
The good news is that in the last few years, California has greatly increased the amount of batteries on the grid. Since 2019, California has gone from just 770 MW of battery storage capacity to over 10,000 MW of battery storage on the grid today. Thanks to this massive battery-buildout, California reached an impressive milestone this year: for 100 days, renewable energy met 100% of demand for at least part of the day. This huge accomplishment shows us that meeting demand with clean energy is possible and we know what it takes to get there.
Put in perspective, a single 20 MW battery could meet the energy needs of more than 10,000 California homes during peak demand. When paired with solar and wind energy, batteries create powerful, reliable clean energy sources, ready to deploy when energy demand is high.
We’re seeing in real-time how batteries can help meet our energy demands. In October 2024, California saw triple digit temperatures across the state, with excessive heat warnings in many regions. From October 4th through 6th, over 8,000 MW of battery storage were deployed each day in the evening hours to help the state meet peak energy demand. On October 6th, this meant that batteries provided 22% of total energy load during peak demand (Figure 2).
Figure 2: Solar and Battery Energy on the CAISO Grid on October 6th.
Even though we are seeing great progress, California is far from meeting its clean energy goals. According to Governor Newsom, in order to reach the state’s climate goals, California needs 52,000 MW of energy storage capacity by 2045. That means we have the tall task of building out 40,000 MW of battery capacity in the next 21 years, a four-fold increase from current levels. This number might be higher depending on electrification of buildings and vehicles, and depending on how much the state relies on less-than-ideal carbon capture and sequestration and hydrogen combustion, technologies that distract from real climate solutions.
Goodbye Dirty Gas, Hello Batteries!
Figure 3: Yellow dots represent operational methane gas plants in California.
If California truly wants to meet its ambitious climate goals in an equitable and just way, it must retire the more than 160 gas power plants still operating in the state, over half of which are in historically disadvantaged communities. Not only do these power plants contribute to greenhouse gas emissions and the climate crisis, they also pollute surrounding communities causing detrimental health impacts like asthma and cancer. Batteries are going to be critical to shutting down these power plants. A 2023 study conducted by the California Energy Commission determined that Long Duration Energy Storage (LDES), like batteries, will be necessary for decarbonizing the grid. In fact, the study found that building out 37 GW of battery storage by 2045 could allow the state to reach zero emissions.
We are seeing more and more attempts to keep these gas plants alive, through fossil fuel-funded technology like hydrogen combustion. However, except in limited instances of helping decarbonize areas that are especially hard-to-electrify—like steelmaking, ships and airplanes—hydrogen is not a clean energy solution. Transitioning gas-fired power plants to burn hydrogen near communities, which California has plans for, has detrimental health and climate impacts. For example, although burning hydrogen does not release carbon dioxide emissions, like burning methane does, it does still emit Nitrogen Oxides (NOx). NOx emissions are linked to asthma and other respiratory illnesses, as well as increased emergency room visits. NOx emissions also interact with other atmospheric pollutants to form ozone, a climate warming pollutant, and smog. This is especially concerning for parts of the state, like Los Angeles, that already do not meet National Ambient Air Quality Standards for ozone. What’s more, hydrogen combustion extends the life of polluting gas plants. These plants would first burn a blend of methane and hydrogen (typically 70% and 30%, respectively), meaning that methane gas and the associated carbon emissions will continue until the plants are retrofitted to burn 100% hydrogen.
We know what technologies are effective in creating a just transition to clean energy and California leaders must continue to invest heavily in these solutions, including responsibly-sited solar and wind projects, offshore wind, distributed energy resources like rooftop solar paired with batteries, and battery energy storage systems. Additionally, investments in energy efficiency and demand response programs are critical to decreasing energy demand. After all, the cleanest and cheapest energy is the energy we don’t use.
Sierra Club is working to support and speed up California’s transition to clean energy in a responsible and just manner. We need your help to ensure that California doesn’t miss its clean energy targets. Get involved in our Electric Sector campaign today!
Questions? Email julia.dowell@sierraclub.org