Energy Vault Starts Construction for Hydrogen Energy Storage System

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The Hybrid Green Hydrogen plus battery energy storage system (BH-ESS) is a utility-scale, long-duration solution with 293 MWh of carbon-free energy.

Energy Vault Holdings began construction on a previously announced deployment of a utility-scale green hydrogen plus battery ultra-long duration energy storage system (BH-ESS) in Calistoga, CA. The BH-ESS provides 293 MWh of dispatchable carbon-free energy. Energy Vault is developing the BH-ESS, named the Calistoga Resiliency Center, for Pacific Gas and Electric Company (PG&E) on less than an acre of land and is scheduled for completion by the end of Q2 2024.

“The timely start of construction is an important milestone in our partnership with PG&E to deliver this microgrid solution. We greatly look forward to not only its delivery but most importantly to the sustainability benefits it will bring to the Calistoga community,” said Marco Terruzzin, Chief Commercial and Product Officer, Energy Vault. “Our partnership with California’s largest public utility is yet another example of the growing recognition that optimizing grid resiliency and economics toward achieving decarbonization goals requires innovation that leverages multiple technologies and a ‘fit-for-purpose’ customer-centric approach when designing energy storage solutions.”


The system’s battery will be used to support grid forming and black start capabilities. The BH-ESS will power downtown Calistoga and the surrounding locations for up to 48 hours during Public Safety Power Shutoffs (PSPS), which occur when powerlines must be turned off for safety during times of high wildfire potential. PG&E received approval for the system from the California Public Utilities Commission (CPUP) in April 2023.

Energy Vault’s BH-ESS will replace mobile diesel generators currently used to energize PG&E’s Calistoga microgrid during PSPS activities in the area. This system will be owned, operated, and maintained by Energy Vault under a long-term tolling agreement with PG&E. The company will use its VaultOS Energy Management System to control, manage, and optimize BH-ESS operations. VaultOS has been developed within the scope of Energy Vault’s H-VAULT suite of hybrid configurations leveraging green hydrogen and battery technology, which ensures resilience during PSPS events.

“Deploying cost-effective, next-generation energy supply and long-term storage technologies is essential to ensuring grid reliability and to achieving PG&E’s goal of a net zero energy system by 2040,” said Mike Delaney, Vice President, Utility Partnerships and Innovation. “PG&E is developing a portfolio of promising new forms of electricity generation and storage technologies, and identifying the right applications that will support the further proliferation of these technologies at the lowest capital cost and highest-impact locations.”

Combining the ultra-long duration capabilities of green hydrogen fuel cells and the fast response of B-VAULT lithium-ion batteries, H-VAULT will provide clean, reliable, low-cost back-up power to enable islanded microgrids during transmission outages. Per the 10.5-year agreement, Energy Vault will provide distributed generation-enabled microgrid services (DGEMS)—a type of energy service that involves grid-forming generation and storage resources. DGEMS provide energy, fault current contribution, and regulate voltage and frequency for Calistoga’s microgrid during scheduled shutoffs.