A tank that holds liquid hydrogen, left, which is converted to gas to run the fuel cells, sits at at Energy Vault, a company that is creating an emergency power system that relies on hydrogen and battery storage, on Tuesday, May 27, 2025, in Calistoga, Calif. (AP Photo/Annika Hammerschlag)
Burn scars from the 2017 Tubbs Fire, visible on the trees without leaves, stand along a ridge Tuesday, May 27, 2025, in Calistoga, Calif. (AP Photo/Annika Hammerschlag)
Energy Vault CEO Robert Piconi poses for a portrait Tuesday, May 27, 2025, in Calistoga, Calif. Energy Vault is creating an emergency power system that relies on hydrogen and battery storage. (AP Photo/Annika Hammerschlag)
A worker lays cables at Energy Vault, a company that is creating an emergency power system that relies on hydrogen and battery storage, on Tuesday, May 27, 2025, in Calistoga, Calif. (AP Photo/Annika Hammerschlag)
An employee drives a forklift at Energy Vault, a company that is creating an emergency power system that relies on hydrogen and battery storage, on Tuesday, May 27, 2025, in Calistoga, Calif. (AP Photo/Annika Hammerschlag)
A power line connected to the grid stands in Calistoga, Calif., Tuesday, May 27, 2025. It will carry electricity from a backup system powered by hydrogen and batteries. (AP Photo/Annika Hammerschlag)
Brush grows in Calistoga, Calif., Tuesday, May 27, 2025. (AP Photo/Annika Hammerschlag)
Calistoga resident and City Council member Lisa Gift poses for a portrait Tuesday, May 27, 2025, at the community garden in Calistoga, Calif. (AP Photo/Annika Hammerschlag)
An employee works at Energy Vault on Tuesday, May 27, 2025, in Calistoga, Calif., where the company is building an emergency power system using hydrogen and battery storage. (AP Photo/Annika Hammerschlag)
Kendell Weis pedals on a popular bike path past a dog park that used to house noisy diesel generators on Tuesday, May 27, 2025, in Calistoga, Calif. (AP Photo/Annika Hammerschlag)