The ability to increase the mix of renewables on campus by tenfold is truly significant. With power-to-gas technology, you don’t need to stop renewable power generation when demand is low. Instead, the excess electricity can be used to make hydrogen that can be integrated into existing natural gas pipeline infrastructure and stored for later use. The Southern California Gas Company system alone is made up of over 100,000 miles of pipeline. This study suggests that we could leverage that installed infrastructure for storage and significantly increase the amount of renewable power generation deployed in California.

—Jack Brouwer, associate professor of mechanical & aerospace engineering and civil & environmental engineering at UCI and associate director of the Advanced Power & Energy Program (APEP)

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.

The central component of the process is the electrolyzer, which takes in water and uses excess clean electricity to power an electrochemical reaction that splits it into hydrogen and oxygen. The latter is released into the atmosphere, and the hydrogen is compressed and sent about 60 feet through a pencil-thin, stainless steel tube to an injection point in UCI’s natural gas pipeline. The hydrogen is mixed with natural gas and burned in the gas turbine power plant to generate electricity and heat for the campus.

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 US Department of Energy future cost of $200 per kilowatt hour.  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 conversion of renewable electricity to hydrogen enables long-term storage of large amounts of carbon-free power. This is a significant advantage over lithium ion batteries, which store energy for shorter time periods and will require extensive construction of battery systems and infrastructure.

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. Power-to-gas systems are currently in place in Germany and Canada.

The study used data from the UCI campus microgrid, which includes solar panels that produce about 4 megawatts 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 megawatts of solar panels. The increased solar deployment raised the fraction of renewable power used on campus from 3.5% to 35%.