California state energy regulators are considering a multi-faceted microgrid project that would incorporate renewables to power electrolyzers producing green hydrogen to then propel a fuel cell system and energy storage providing long-term backup resiliency for a city’s electric system during outages.
Northern California utility Pacific Gas & Electric is contracting Energy Vault to deliver, own and operate a large battery-plus-hydrogen energy storage system in its service territory. The planned 293-MWh hybrid microgrid would provide carbon-free electricity for the city of Calistoga during planned outages and potential public safety power shutoffs (PSPS) due to wildfire risks.
The California Public Utilities Commission is reviewing the PG&E proposal and could make a decision by May 15. PG&E is the primary service provider for power in that region of northern California.
The system, if approved and installed and commissioned, could replace diesel generators which have provided the backup power previously.
“This breakthrough collaboration between PG&E and Energy Vault provides a template for future, renewable community-scale microgrids that successfully integrate third-party distributed energy resources,” Ron Richardson, the utility regional vice president for North Bay and North Coast, said in a statement.
The proposed microgrid includes several layers on the way to backup electricity generation. First of all, renewable energy resources such as wind and solar would power electrolyzers, which use electricity to split water and capture the hydrogen. The H2 then fuels the fuel-cell technology, which converts the H2 into electricity for battery storage.
Hydrogen does not include carbon in its chain, so does not emit CO2 when combusted. Many companies and power entities throughout the world are exploring H2-fired power capacity as a means of decarbonization, although the fuel has many challenges in getting scaled up.
The size of this Calistoga microgrid being designed by Energy Vault could deliver up to 48 hours of power for the system during outages, according to the release.
In May 2022, PG&E announced it was launching an in-depth study on the feasibility of moving hydrogen through natural gas pipelines. A demonstration project, Hydrogen to Infinity, would blend H2 and methane natural gas in a stand-alone transmission pipeline system.
One challenge with hydrogen is that it is the lightest element. It also takes more energy to produce than H2 delivers when it converted to power, according to reports.
Hydrogen, however, does provide the promise of a combustible and baseload, yet carbon-free form of energy resource.
Construction on the Calistoga H2-Battery Microgrid would begin in the fourth quarter, pending approvals. Completion and operations would be expected in the second half of 2024, according to reports.
The release by PG&E and Energy Vault says it could be the largest utility-scale green hydrogen project in the U.S. At the same time, companies including Mitsubishi Power, Black & Veatch and Intermountain Power Agency are working on a sizable blending project in Utah.
Calistoga is a popular tourist destination within northern California's wine country.
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(Rod Walton, senior editor for EnergyTech, is a 15-year veteran of covering the energy industry both as a newspaper and trade journalist. He can be reached at [email protected]).
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