Designed to power downtown Calistoga, California, US, and its surrounding area, the 293MWh BH-ESS system integrates a short duration battery system for grid forming and black start capabilities, with long duration fuel cells and a liquid green hydrogen storage system, to replace existing mobile diesel generators.

The companies say the BH-ESS could power customers for a minimum of 48 hours during planned outages and any potential public safety power shutoffs (PSPS).

H2 View understands the system which is set to be owned, operated, and maintained by Energy Vault, while providing dispatchable power under a 10 and a half year tolling agreement with PG&E.

Despite the project still awaiting final resolution for approval from the California Public Utilities Commission (CPUC), the companies have said it could be expanded to 700MWh, allowing for longer operation times between refuelling.

Construction is expected to begin in the fourth quarter of 2023 with commercial operation hoped to kick off by the end of Q2 in 2024. According to Energy Vault and PG&E, the project, upon completion is expected to be the first-of-its-kind and the ‘largest’ utility-scale green hydrogen project in the US.

“We’re excited to partner with PG&E on this ground-breaking project that reflects Energy Vault’s differentiated ability to design, build and operate innovative and utility-scale energy storage solutions that meet our customers’ specific needs in achieving their grid reliability and decarbonisation goals,” said Robert Piconi, Chairman and Chief Executive Officer of Energy Vault.

“We are setting a new benchmark for what can be achieved with an innovative design that integrates the most advanced energy storage mediums in order to deliver a fully renewable green hydrogen battery energy storage system,” Piconi added.