Excess electricity from renewable sources will be converted to hydrogen under the demonstration

Power-to-gas green energy storage demonstrations launched in US

A series of power-to-gas demonstrations designed to store excess green energy will be the first of their kind in the USA.

The technology uses electricity from renewable sources like solar to drive electrolysis reactions that create hydrogen gas from water, which can then be used as an energy source in its own right or converted into synthetic methane by combining it with the greenhouse gas CO2.

Renewable energy’s reliance on the weather means supply and demand are not always aligned, so finding ways of storing energy during times of excess supply to meet demands when supply drops below consumption will be key to the growth of the renewable energy sector.

The project is the result of a partnership between utility Southern California Gas Company (SoCalGas), the Energy Department's National Renewable Energy Laboratory (NREL) and the National Fuel Cell Research Center (NFCRC).

"A power-to-gas system can help California meet environmentally-focused energy goals and solve a major energy challenge facing our nation: how to cost-effectively store excess power from renewables to meet energy demands when the wind does not blow or the sun does not shine," said Patrick Lee, senior vice president at SoCalGas.

Battery technology is still limited to short-term storage and their high cost and limited capacity make them unfit for utility scale storage, prompting a search for novel storage solutions.

Commercial-scale power-to-gas systems are already up and running in Germany and SoCalGas says the technology could allow utilities across the US to use existing pipeline infrastructure to store and deliver clean energy on demand.

The hydrogen produced by the system can either be blended with the methane in the utilities distribution system, lowering the carbon content of gas supply, or combined with CO2 from sources such as carbon capture technology used by fossil fuel-based generators.

"As we reach high levels of renewable energy on the grid, storing the electricity generated by solar power and other variable energy sources will help unlock greater use of these renewable resources in the US and throughout the world," said Dr Martha Symko-Davies, director of partnerships for energy systems integration for NREL. "This project will examine a unique way to reduce the capital cost of energy storage."

The demonstration will be based at the NFCRC at the University of California, Irvine and NREL's laboratories in Golden, Colorado and as well as testing the fundamental technology the demonstrations will assess the feasibility of using the natural gas pipeline system to store renewable energy.

"With the extensive storage capacity of natural gas infrastructure, this project will provide important validation of the technical and economic feasibility of carbon-free energy transformation and storage," said Professor Scott Samuelsen, director of the NFCRC.

Initial project results are expected by year end.

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