By: Risto Paldanius, Vice President, Americas at Wärtsilä

In 2020, Wärtsilä’s state-of-the-art power-system modeling revealed that California can reach its renewable energy and emissions targets faster than planned while saving ratepayers billions of dollars. Now, two years later, that projection is coming to fruition with recent developments in the Golden State. 

According to the California Independent System Operator (CAISO), the state’s main grid ran on more than 97% renewable energy at 3:39 p.m. on Sunday, April 3, breaking a previous record of 96.4% that was set just a week earlier. 

Additionally, San Diego Gas & Electric (SDGE) recently released a study, “The Path to Net Zero: A Decarbonization Roadmap for California,” incorporating the utility industry standard for reliability using industry-specific planning tools to chart what we believe to be an achievable approach. 

SDGE has used similar tools as Wärtsilä’s PLEXOS power-system modeling that lays out the Optimal Path for California to decarbonize the electricity sector completely. SDGE’s study acknowledges that they need large quantities of firm and flexible power and the current decision of closing down all thermal power entities in California is a mistake. 

Risto Paldanius VP, Wartsila Energy

Key Insight from the Study:

  •   California is estimated to need to decarbonize at 4.5 times the pace over the past decade to reach its carbon neutrality goal and mitigate the negative impacts of climate change.
  •   Electric generation capacity is estimated to need to increase to about four times (4x) the capacity that existed in 2020, in order to support transportation and building electrification. Between 2020 and 2045, electric consumption is expected to increase by 96%.
  •   To keep electric service reliable, California will need to complement its growing portfolio of intermittent solar and wind generation with a mix of clean, firm and flexible resources that can be dispatched at any time to meet needs. Installing 40 GW of new battery storage, as well as 20 GW of dispatchable generation from 100% clean hydrogen combustion by 2045, is projected as necessary to meet this goal. According to CAISO,, the statewide grid has interconnected about 2,600 MW of energy storage as of January 2022, but no electric generation from 100% clean hydrogen combustion. 
  •   It is estimated that by 2045, there will be demand for 6.5 million metric tons of clean hydrogen across the economy, 80% of which is projected to be used to enhance the reliability of the electric supply.
  •   The implementation of the Roadmap requires regulatory and political support from four fronts to: 1) prioritize electric sector reliability; 2) maintain affordability and enhance equity; 3) incentivize innovation and adaptability; 4) and enable the deployment of decarbonization infrastructure. 

San Diego Professor David G. Victor served as the study’s advisor and echoed one of its key findings. “While the exact combination of technologies and investments needed to get to net zero is unknown at this time, what is certain today is that a flexible and diversified approach to decarbonization is both prudent and necessary to help ensure we are eliminating carbon emissions while also safeguarding grid reliability,” he said. 

California gets about 30% of its electricity from renewable sources. To compensate for renewables’ variability and keep the grid balanced, the state depends on fossil-fuel-powered plants. These traditional gas power plants are inflexible. They cannot switch off quickly when the sun shines brightly and then switch back on a few hours later; rather, they must stay online all the time. So in California, solar energy is being curtailed and at the same time fossil-fueled power plants are operating. Until this issue is addressed, there is a limit to how much renewable energy the grid can handle.

The Optimal Path would use curtailed solar and wind power to produce renewable carbon-neutral fuel. This fuel could be stored for use in flexible generation plants, which are designed to switch off and on quickly and run only when needed to balance the power system when renewable energy is not available.

Adding this flexible generation from renewable fuels would help California avoid overbuilding renewable generation and battery storage; it would cut solar and wind capacity requirements by 8 GW compared to renewables plus battery storage alone. That would reduce the amount of land needed for solar panels and wind turbines by hundreds of miles, cut costs, alleviate land-use conflicts, and mitigate environmental concerns such as habitat loss.

The path to the decarbonized power system for California in 2045 is dependent on decisions made now. There is no policy level mechanism through which electric utilities can be assured that California will recognize carbon-neutral renewable methane (from PtG process) coupled with firm and flexible assets as “renewable generation.” Such policy would allow utilities to strategically install these “balancers,” as we call them, as needed while also ensuring these assets would contribute positively towards the ideal net-zero power system and enable California to capitalize on its progress and the most recent outlined studies.

Photo by Venti Views on Unsplash