Study: California can Reach a Decarbonized Electric Grid Affordably and Reliably by 2045

A combination of renewables with clean firm sources of energy will be required to make the switch

March 25, 2021
Anne Marie Borrego, (202) 572--3356,

(SAN FRANCISCO—March 25, 2021) California can eliminate carbon emissions and without markedly increasing the cost of electricity while preserving the reliability of the state’s grid, a new analysis in the online journal Issues in Science and Technology published today shows.

The analysis, jointly sponsored by Environmental Defense Fund and Clean Air Task Force utilized advanced modeling provided by Energy & Environmental Economics (E3) Consultancy, Princeton and Stanford Universities, considered a variety of pathways the state could use to achieve to 100% carbon-free electricity. California’s grid must be decarbonized by 2045, under a law (Senate Bill 100) passed in 2018. The law requires that 100% of all retail sales of electricity come from a combination of renewable energy and carbon-zero resources. By 2030, 60% will need to come from renewable energy—excluding hydropower. The law is complemented by a 2018 Executive Order B-55-18 that seeks to move California to a carbon neutral economy by 2045.  The study results fulfill the requirements of both the state law and the carbon neutrality Executive Order.

California currently relies primarily on natural gas for most of its electricity. Renewables like solar and wind are a growing share of the grid’s generation, but supplies can drop up to 60% from summer to winter. While batteries can be useful in dealing with the variation in solar and wind power during the day, they are not able to pull the state through several weeks of reduced supply. Since California seeks to electrify many current uses of fuel, and this will double its electricity demand from 50 gigawatts today to about 100 gigawatts by midcentury, the state will need to find ways to generate clean, reliable electricity while ensuring that costs remain reasonable to customers.

The study employed three different models of California’s electricity system to quantify the costs of a variety of future scenarios for new sources of clean, reliable electric power. Each team’s model determined how much electricity would cost under a variety of scenarios. The models also considered the physical implications of building the decarbonized grid, examining questions like how much infrastructure would be required; how quickly the state would need to build it; and how much land would be needed. While each team approached the challenge differently, they all produced similar results that kept the cost of generation and transmission between 7 and 10 cents per kilowatt hour, comparable to the current costs of generation and transmission for California’s investor-owned utilities.

While the teams found that renewables like wind and solar will remain critical to the state’s path toward decarbonization, California will need to tap into clean electricity that is available on demand, for as long as it is needed, whenever it is needed. Known as “clean firm power,” this type of energy includes geothermal and nuclear power as well as natural gas that utilizes carbon capture and storage technology to sequester CO2. Clean fuels such as hydrogen manufactured with no life-cycle emissions could also be added to the mix. 

“California needs to develop a plan for 60% renewable energy by 2030 and roughly 30 GW of clean firm capacity by 2045 that allows the state flexibility to evaluate a variety of pathways to meet its goals,” says Jane Long, senior contributing scientist at EDF and lead author of the paper.

“California has a lot of options for clean firm power, but the key is getting started with the policies and investments to make those options real” says Armond Cohen Executive Director of Clean Air Task Force.  To reach goals outlined in the legislation, California should incentivize the development of technologies that include but are not limited to:

· Retrofitting existing natural gas generators with carbon capture and storage;

· Zero-carbon fuels (biomethane, synthetic methane, hydrogen or ammonia from carbon-neutral processes);

· Conventional and enhanced geothermal energy technologies;

· Biomass with carbon capture and storage; and

· New domestic or imported nuclear energy (including advanced small modular reactors).

“This study indicates that clean firm power will play an important role in rapidly and equitably decarbonizing the electric grid, both in California and in other states, many of which do not share the state’s rich renewable potential,” Steven Hamburg, EDF’s Chief Scientist said. “Other states have the opportunity to learn from California’s experience as they consider their own decarbonization strategies.”

“This work demonstrates that California can reliably and affordably decarbonize our electric grid,” said Michael Colvin, director of EDF’s California energy program. “We must engage with diverse communities across the state to ensure that the benefits of future investments in our clean energy infrastructure are accessible and equitable for all Californians.”  

To explore the report, including results from each of the modeling teams visit

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