California wants 100% renewable power. It just hit that milestone — briefly
Save A Lot Solar installer Elvin Ramirez-Castro carries the final panel of an array during a project on the roof of a home in Oakland. Renewable power production essentially matched the state’s demand for a time on April 30. Don Feria/Special to The Chronicle
California hit a major clean energy milestone over the weekend when the state’s renewable power sources like solar and wind generated essentially as much electricity as the state needed.
The record occurred shortly before 3 p.m. on Saturday, as solar power production soared before late-afternoon power demand kicked in.
“California achieved 100% renewable energy today. Very clear we can achieve clean energy everyday before 2030 if we cut the fossil fuel subsidies and political inertia,” Daniel Kammen, an energy professor at UC Berkeley, wrote on Twitter.
The California Independent System Operator, which manages the state’s grid, said that the share of renewable energy peaked at 99.87% — marking a record for the state, albeit a fleeting one.
A brief time period does not reflect the overall electricity picture in California. Spring is a time of relatively low power demand, because moderate temperatures outside mean less need for heating or cooling, and longer days bring high solar power production.
Huge solar farms like this one, a nearly 750,000-panel array near Santa Margarita (San Luis Obispo County), have helped power California to new records of renewable energy production. Michael Macor/The Chronicle 2015
Californians still rely heavily on natural gas throughout the year. Natural gas provided 37% of energy in the state in 2020 — more than the 33% of all renewable energy sources combined, the latest data from the California Energy Commission. Solar power provided 13% and wind 11% of the state’s electricity.
Still, clean power advocates viewed Saturday’s marker as brief but stunning proof of the energy shift made over the past several decades. California must get 100% of its electricity from carbon-free sources by 2045 if it is to meet a goal signed into law nearly four years ago by then-Gov. Jerry Brown.
“It wasn’t all day, it wasn’t all weekend and we have a long way to go before we’re not burning fossil fuels — but we definitely can get there,” said Laura Deehan, state director with Environment California, a nonprofit renewable energy advocacy group.
The state has tripled its use of renewable power sources over the past ten years, mostly with new wind and solar projects. Other renewable energy sources include geothermal, biomass from wood products and biogas from food scraps and animal waste. Although nuclear is a carbon-free energy source, it is not included in the electric grid operator’s renewable energy calculator. Large hydroelectric dams are also not included as renewable energy sources because, although they do not generate greenhouse gases, they can cause other environmental problems like habitat destruction.
Mark Jacobson, a professor of civil and environmental engineering at Stanford, noted that wind, hydropower and solar together met 80% of the state’s electricity demand for eight hours straight on Saturday.
Clean power advocates had been closely watching the percentage of renewable energy production inch closer to demand since April 14, when the state hit an earlier record of 97%. Californians have been using mostly renewable energy for much of the spring, aided by mild weather.
On Saturday, California reported its renewable energy sources rising above demand for the first time at 2:05 p.m., producing 17,636 megawatts compared to electricity demand, which was listed at 17,548 megawatts, according to operator data. That continued for about an hour until demand slipped above production at 5:05 p.m. At its peak, production exceeded demand by 623 megawatts at 2:40 p.m.
Those figures don’t account for how much energy is lost when it is transmitted from the source, typically estimated at 5%, according to Mike O’Boyle, director of electricity policy with Energy Innovation, a nonpartisan clean energy organization. And the state’s energy supply is much more complex.
O’Boyle noted that California was still burning natural gas during that record-breaking time because the state cannot completely turn off those systems for a variety of reasons. For one, solar power production plummets when the sun sets.
Excess renewable energy produced in California can be sold to other states, O’Boyle said.
The data also doesn’t include energy demand from about 10% of the state, including districts in Los Angeles and Sacramento. The system operator manages about 90% of the state’s electric grid.
O’Boyle still considered Saturday’s balance of renewable energy “a really important and big milestone.” And by his calculations, adding hydroelectric and nuclear power showed the state operated with 100% carbon-free electricity for six-and-a-half hours Saturday, even with energy lost during transmission.
“The puzzle now is, how do we keep building renewable energy resources in a way that we turn this one-time success into repeatable success?” O’Boyle said.
Julie Johnson (she/her) is a San Francisco Chronicle staff writer. Email: julie.johnson@sfchronicle.com Twitter: @juliejohnson