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Southern California Gas Co. has started two pilot projects that will test the feasibility of using solar energy produced when power demand is low to split hydrogen from water and store the gas in pipelines.

The projects, backed by U.S. government funding, will either ship the hydrogen for use as an automotive fuel or combine it with carbon dioxide to form methane that can be used to generate electricity when demand is stronger.

The company is pitching the technology, already used in Germany with wind energy, as an alternative to battery storage. Renewable fuels must make up a third of California’s power supply by 2020, according to state law.

“I think everyone knows that in meeting that requirement you will need a lot of storage,” Jeffrey Reed, director of business strategy and advanced technology for the utility, a unit of San Diego-based Sempra Energy, said in an April 9 phone interview. “We need resources to match the time of production with the time of use.”

The cost of storing power converted to gas is less than 35 cents per kilowatt-hour, according to analysis by Southern California Gas.

Once put onto the pipeline network system, wholesale power prices and the price of gasoline at the pump will determine how those gases are used, said Patrick Lee, senior vice president of customer service, innovation and business strategy for the utility in Los Angeles.

Fuel Flexibility

“It’s really a flexible fuel that depends on the market economics,” said Lee. “It’s especially suitable for long-term storage.” Germany is already using the process with surplus wind produced overnight, he said.

As part of the projects, the National Renewable Energy Laboratory in Golden, Colorado, will produce the hydrogen and combine it with carbon dioxide, a greenhouse gas linked to global warming, to make methane with a negative carbon footprint, Reed said. The National Fuel Cell Research Center at University of California, Irvine, will test the hydrogen for vehicle use and determine how much of the gas can be injected into the pipeline system.

Initially, the projects will convert about 200 kilowatts of solar power, producing enough hydrogen to fill up five or six vehicles a day. A year later the utility plans to produce 1 megawatt, enough to fill the storage tanks at a large filling station, Lee said.