New research on power-to-gas technology suggests the energy storage technique holds the ability to increase the use of intermittent renewable energy.

The finding came from research conducted at the University of California, Irvine (UCI) and funded by Southern California Gas. Preliminary research findings, announced this week demonstrated that the campus microgrid could increase the portion of renewable energy it uses from 3.5% to 35% by implementing a power-to-gas strategy.

"This research clearly shows that power-to-gas technology can increase the use of renewable energy and should be an important component in meeting California's clean energy and greenhouse gas reduction goals," says Jeff Reed, director of business strategy and advanced technology at SoCalGas.

With power-to-gas technology, excess electricity can be used to make hydrogen that can be integrated into existing natural gas pipeline infrastructure and stored for later use. The SoCalGas system includes more than 100,000 miles of pipeline. The study suggests that the installed infrastructure could be used for storage and increase the amount of renewable power generation deployed in California.

There are three potential uses for the stored hydrogen:

• Using hydrogen gas directly (or blended with natural gas) in applications such as power generation or vehicle fuel
• Feeding fuel cells by injecting hydrogen and either oxygen or air into the cell to produce electricity from the resultant chemical reaction
• Combining the hydrogen (H₂) with carbon dioxide (CO₂) to create synthetic methane (CH₄), which could be used as a replacement for natural gas

The U.S. Energy Department (DOE) says that the commercial use of power-to-gas technology is primarily being considered in Europe, where it is being reviewed by the European Gas Research Group, as well as the energy departments of several nations.

In Germany alone 18 different experimental programs are being conducted.

The research in California, which also involves the National Renewable Energy Laboratory, is exploring various ways to use hydrogen produced through electrolysis, including hydrogen injection into the natural gas pipeline and storage infrastructure, synthetic methane production through biomethanization, and fuel cell applications.

Power-to-gas can help address grid-stability problems that arise when an increasing share of power is generated from sources that have a highly variable output. Solar and wind accounted for nearly 5% of U.S. net electricity generation in 2014, and they are forecast to account for a greater share of the emerging generation portfolio.

In practice, power-to-gas technology takes excess renewable electricity which would otherwise go to waste and converts it to hydrogen, which can then be blended with natural gas and utilized in everything from home appliances to power plants. A 5% blend of hydrogen in SoCalGas' natural gas system would provide storage capacity equivalent to $130 billion worth of battery systems, if purchased at the DOE's future cost of $200 per kilowatt hour, the utility says. Renewable hydrogen can also be used in hydrogen fuel cell vehicles or converted to methane for use in a natural gas pipeline and storage system.

The new finding comes from a pilot project begun with funding from SoCalGas and the participation of Proton OnSite, which manufactured the electrolyzer that produces hydrogen from electricity and water. UCI engineers and graduate students have been working to determine how beneficial the technology might be and its feasibility for statewide or regional power grids.

The study used data from the UCI campus microgrid, which includes solar panels that produce about 4 megawatts (MW) of peak power. Simulations showed that by storing excess solar power on sunny days and using an electrolyzer to produce renewable hydrogen, the microgrid could support an additional 30 MW of solar panels. The increased solar deployment raised the fraction of renewable power used on campus from 3.5% to 35%.