Whatever path California takes to completely decarbonize its retail power sales by 2045, Finland's Wärtsilä Oyj Abp is positioning itself to provide the needed equipment.

A global supplier of reciprocating engines that burn natural gas, Wärtsilä is adapting its engines to run on 100% hydrogen gas or "carbon-neutral" methane, the company said May 5. Such "renewable fuels," sourced from excess wind and solar energy, could help California cost-effectively purge carbon from its power sector by 2040 with long-term energy storage that could utilize existing gas infrastructure, the company claims.

Wärtsilä also is active in energy storage projects using lithium-ion batteries to balance variable renewable generation for a few hours at a time. A recently announced 70-MW project, for instance, is nearing completion adjacent to an existing wind farm in California.

Like other suppliers, Wärtsilä aims to expand the market for energy storage in the U.S. Southwest, particularly in California. Both long- and short-duration energy storage are widely viewed as essential enablers for California to reach its targets of covering 60% of all-electric retail sales with renewable energy by 2030 and 100% with carbon-free resources by 2045.

The state's current plan, however, would leave some thermal generation online under a disputed interpretation of the 100% Clean Energy Act of 2018, also known as Senate Bill 100, an outcome that Wärtsilä says it can avoid. The state also runs the risk of leaning too heavily on short-term battery storage, producing large volumes of renewable energy oversupplies and driving costs higher, according to Joe Ferrari, general manager of utility market development at Wartsila North America Inc.

The path to 100%

During a May 5 online panel discussion, Ferrari argued that California's fastest, cheapest route to decarbonizing its grid is to combine wind, solar and battery storage additions with new flexible power plants that can burn natural gas now and shift to 100% renewable energy-sourced methane or hydrogen over time.

One such conversion is proposed at a major power plant in Utah, in a project being led by the Los Angeles Department of Water and Power, relying on advanced turbines from Mitsubishi Hitachi Power Systems Americas Inc.

"We think it's the best path to reach 100% clean energy for California," Ferrari said, promising "a faster, more complete decarbonization," and "very competitive rates for ratepayers."

Currently, California's utilities plan to fill gaps in generation capacity that could emerge as older natural gas power plants retire with battery storage projects, many coupled with solar farms.

That may not suffice, said Karl Meeusen, senior advisor of infrastructure and regulatory policy at the California ISO, during the panel discussion. Given increasing amounts of variable wind and solar, the state needs a "diverse and dispatchable fleet" in addition to "multiday" storage, he said.

Regulatory and legislative changes would be needed, said Jan Smutny-Jones, CEO of the Independent Energy Producers Association, a trade group representing gas, storage and renewable power plant developers, to formally recognize synthetic methane and renewable hydrogen as resources for the purpose of meeting California's clean energy targets.

"I think right now what is most important for California's future is to have a broad view of ... the true options that are in front of us and an ability to think creatively," Meeusen said.