SoCal Gas said a pilot program it funds has successfully injected hydrogen — created with the use of excess renewable power — into a natural gas pipeline using technology that may one day help smooth the intermittent nature of solar and wind power.
SoCal's power-to-gas (P2G) pilot program at the University of California Irvine's Advanced Power & Energy Program has converted surplus renewable solar and wind energy into hydrogen which can be blended with natural gas for use in homes or as a power-plant fuel.
The research "lays the groundwork for leveraging the natural gas infrastructure already in place for the storage and transmission of renewable energy," said Jeff Reed, SoCal's director of business strategy and advanced technology.
As wind and solar production increases "energy storage will be a critical component for grid reliability," Reed said.
Wind generation often peaks overnight and in the spring and fall when electric demand is low. The California grid struggles with excess solar generation daily which reduces demand and profitability for the state's existing gas-fired generators.
"One of the big challenges we have faced in adding wind and solar to the grid is what to do with the excess electricity," said Jack Brouwer, associate director of the university's advanced energy program. P2G technology offers a way to avoid curtailing renewable output when electric demand is low. Instead, excess electricity can be used to make hydrogen that can be integrated into the existing gas pipeline network for use at a later time, Brouwer said.
The technology utilizes an electrolyzer that uses excess renewable electricity to split water into hydrogen and oxygen. Oxygen is released into the atmosphere while the hydrogen is compressed and sent through a stainless steel tube to an injection point in a gas pipeline near a university power plant. Hydrogen mixes with natural gas and is burned to generate electricity and heat for the campus.
Hydrogen produced from electricity and water can also be converted into methane and injected into a pipeline system for distribution or to be stored underground. SoCal said more than 12TWh of electric equivalent storage can be accommodated on its system in southern California.
The pilot project began last summer. The technology is also in use in Germany which is working to integrate its abundant renewable generation. California researchers are monitoring the process to determine whether P2G is feasible on statewide or regional power grids.
California has a mandate to use renewables to supply 50pc of its electricity by 2030. San Diego has a more ambitious goal of goal of using 100pc renewable energy use by 2035.
San Diego Gas & Electric, the main utility for the city, is owned by Sempra Energy, also the parent of SoCal Gas.
Storage of hydrogen in existing gas infrastructure "could become the most important technology for enabling a 100-percent renewable future," Brouwer said.
US tech company Google said this week it is on track to buy enough renewable power to match 100pc of its operations in 2017 although it cannot buy renewable power exclusively. To meet its goal, Google will use a mix of direct energy purchases, the retirement of renewable energy certificates and utility tariff programs. Google ranks as the world's largest corporate buyer of wind and solar power, followed by Microsoft, Cisco Systems, Apple, Kohl's department stores and others.
