Energy Vault, PG&E Announce Successful Completion of the Calistoga Resiliency Center, the World's First Ultra-Long Duration Hybrid Battery + Hydrogen Energy Storage Microgrid

First-of-a-kind and fully sustainable microgrid platform, developed to support the long-term vision of the California Public Utilities Commission and Pacific Gas and Electric Company to ensure Calistoga's power resiliency during Public Safety Power Shutoffs (PSPS), creates blueprint for future installations across California and the USA

OAKLAND, Calif. and WESTLAKE VILLAGE, Calif., Sept. 25, 2025 /PRNewswire/ -- Energy Vault Holdings Inc. (NYSE: NRGV) ("Energy Vault"), a leader in sustainable, grid-scale energy storage solutions, and Pacific Gas and Electric Company (PG&E), a subsidiary of PG&E Corporation (NYSE: PCG), today announced the successful completion and commercial operation of the Calistoga Resiliency Center (CRC), a state-of-the-art hybrid microgrid energy storage facility, located in Calistoga, Calif., that integrates advanced hydrogen fuel cells with lithium-ion batteries. This landmark project provides a unique, fully sustainable solution to address power resiliency amidst the growing challenges of wildfire risk in California.

Calistoga Resiliency Center

Serving approximately 1,600 PG&E customers in and around downtown Calistoga, the CRC represents a transformative step forward in addressing the need for Public Safety Power Shutoffs (PSPS) due to wildfires and extreme weather events. The 293 megawatt hour (MWh) microgrid system enables the isolated Calistoga community microgrid to maintain power during these necessary safety shutoffs, delivering at least 48 hours of continuous energy supply with a peak power output of 8.5 megawatts (MW) during PSPS events. This zero-emission system aligns with California's Renewable Portfolio Standard (RPS) while meeting PG&E's multi-day, long-duration energy storage requirements. The system is orchestrated by Energy Vault's technology-agnostic VaultOS™ Energy Management System, enabling black-start, grid forming and coordinated performance orchestration across all subsystems while communicating with PG&E's Distribution Control Center.

"This project is a major milestone in our mission to deliver sustainable, resilient energy solutions to communities most vulnerable to climate-driven grid disruptions," said Craig Horne, Senior Vice President, Advanced Energy Solutions, Energy Vault. "The Calistoga Resiliency Center exemplifies the power of innovation and partnership, and it marks a significant step forward in the execution of our 'Own & Operate' strategy, which enables us to deliver long-term value through recurring revenue and community impact."

When operating in island mode, the CRC utilizes hydrogen fuel cells for electricity generation, providing essential power to the community. After supporting black-start and grid forming requirements of the microgrid, Energy Vault's B-VAULT™ DC battery technology works in concert with the fuel cells, ensuring instantaneous response and maintaining grid stability throughout operation. The use of liquid hydrogen enables extending run time through delivery and transfer into the onsite storage tank without interrupting power supply to the City of Calistoga while also reducing the cost of resiliency services. The CRC serves as a model for Energy Vault's future utility-scale hybrid microgrid system deployments as the only existing zero-emission solution to address PSPS events that is scalable, bankable, and ready to be deployed across California and other regions prone to wildfires as well as locations where improved grid-resiliency is needed.

The project, facilitated by the recent close of $28 million in financing, inclusive of the completed sale of the Investment Tax Credit associated with the project, is owned and operated by Energy Vault in collaboration with PG&E as the utility partner and distribution system operator under a long-term energy services agreement. The project's completion marks a significant milestone related to Energy Vault's "Own & Operate" strategy, demonstrating the Company's ability to execute on its strategic vision while maximizing capital efficiency. Today's announcement comes on the heels of the recent completion of the Cross Trails BESS, the first project to be placed in service under Energy Vault's growing portfolio of "Owned & Operated" projects.

The Calistoga Resiliency Center is now fully operational and stands as a blueprint for other high-risk communities across California and beyond.

"PG&E is committed to continually delivering innovations that enhance electric system safety and reliability while driving costs down for our customers," said Mike Delaney, Vice President, Utility Partnerships and Innovation, PG&E. "The Calistoga Resiliency Center is another step toward fulfilling that commitment. It is the right solution for PG&E, for Calistoga, and for the planet."

PG&E's Comprehensive Microgrid Solutions

PG&E has deployed 13 distribution microgrids since 2021 to support communities affected by Public Safety Power Shutoffs (PSPS), with Calistoga being the largest and first fully renewable system. These microgrids help keep communities and essential services—like fire stations, medical facilities, and grocery stores—powered during outages. These microgrids can power areas where the power lines are underground, or outside of high fire-threat areas or a PSPS weather footprint.

In addition to distribution microgrids, through its Community Microgrid Enablement Program (CMEP) and Microgrid Incentive Program (MIP), PG&E supports the development of community-driven multi-customer microgrids. In March 2025, PG&E committed up to $43 million to fund nine new community microgrids in the North Coast region.

Additionally, PG&E offers Remote Grid services for customers in high fire-risk areas at the end of long distribution lines. These off-grid systems allow PG&E to remove overhead lines in rugged terrain, reducing wildfire risk.

About Energy Vault

Energy Vault® develops, deploys and operates utility-scale energy storage solutions designed to transform the world's approach to sustainable energy storage. The Company's comprehensive offerings include proprietary battery, gravity and green hydrogen energy storage technologies supporting a variety of customer use cases delivering safe and reliable energy system dispatching and optimization. Each storage solution is supported by the Company's technology-agnostic energy management system software and integration platform. Unique to the industry, Energy Vault's innovative technology portfolio delivers customized short, long and multi-day/ultra-long duration energy storage solutions to help utilities, independent power producers, and large industrial energy users significantly reduce levelized energy costs while maintaining power reliability. Since 2024, Energy Vault has executed an "Own & Operate" asset management strategy developed to generate predictable, recurring and high margin tolling revenue streams, positioning the Company for continued growth in the rapidly evolving energy storage asset infrastructure market. Please visit www.energyvault.com for more information.

About PG&E

Pacific Gas and Electric Company, a subsidiary of PG&E Corporation (NYSE: PCG), is a combined natural gas and electric utility serving more than sixteen million people across 70,000 square miles in Northern and Central California. For more information, visit pge.com, pge.com/news and pge.com/innovation.

SOURCE Pacific Gas and Electric Company