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Project Explores Converting Power to Gas For Storage

A series of demonstration projects and testing of a process for converting renewable-based electricity into natural gas for storage began this month in a three-way effort among Sempra Energy's Southern California Gas Co. (SoCal), the U.S. Department of Energy's National Renewable Energy Laboratory (NREL), and the industry-backed National Fuel Cell Research Center (NFCRC).

A SoCalGas spokesperson told NGI that the demonstrations and other testing will be carried out at the NREL and NFCRC facilities in Colorado and California, respectively. He said initial results should be available before the end of this year. Cost of the project was not disclosed.

At a time when national and state leaders are focusing on climate change and renewable energy, as well as the need to capture and store electricity, the partners in this research and demonstration effort think they are on the right track in finding alternatives to conventional battery storage.

The process they are attempting to bring to commercial use in the United States is already well established in Germany and is being explored for wider global use, according to officials at SoCalGas and the partnering research centers. With large excess renewable-produced power supplies, the Germans have shown the technology is cost-effective and scaleable, being deployed on a decentralized basis in sizes that are akin to a shipping container used in ship and rail transportation to move goods.

"A power-to-gas system can help California meet environmentally focused energy goals and solve a major energy challenges 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 for customer service, innovation and business strategy at SoCalGas.

The concept employs electrolyzer-based methods in taking power produced from intermittent sources such as wind and solar to make what SoCalGas is calling "carbon-free hydrogen gas” by breaking down water into hydrogen and oxygen. Hydrogen then is converted to synthetic, renewable methane -- essentially traditional natural gas -- and stored to meet future needs.

The synthetic gas also could be used directly to fuel natural gas vehicles or hydrogen-powered cars, run microturbines to produce onsite power, and power fuel cells or other equipment.

If commercial-scale power-to-gas systems catch on, SoCalGas officials said natural gas utilities across North America theoretically could use their existing pipeline infrastructure as essentially a large, cost-effective "battery" to store and deliver clean, renewable energy on demand.

For NREL, the demonstration projects are a natural fit, offering a way to store excess photovoltaic and wind power supplies that otherwise would be lost. "As we reach high levels of renewable energy on the grid, storing the electricity generated by solar and other variable energy sources will help unlock greater use of these renewable resources in the United States," said Martha Symko-Davies, NREL director of partnerships for energy systems integration.

To date, the emphasis has been on developing larger and more cost-effective batteries to capture the renewable output more fully, but the battery option remains expensive. Power-to-gas offers longer-term storage capacity and is a cost-effective alternative using the existing natural gas infrastructure, the project backers contend.

"With the extensive storage capacity of natural gas infrastructure, this project will provide important validation of the technical and economic feasibility," said Scott Samuelsen, NRCRC director at the University of California, Irvine.

SoCalGas' power/gas project is expected to provide valuable data on the dynamics of hydrogen production in a system flush with renewable electricity, a company spokesperson said. The key is to determine the best ways to make hydrogen and then how best to get it on the grid, he said.

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