Mendocino iron-air battery

Form Energy · PG&E substation, East Road, Redwood Valley, Mendocino County, CA · California DEVELOPER HEALTHWATCH

California's largest long-duration storage project when funded: 5 MW for 100 hours. Targeted to be online by end of 2025; no newer status found.

Long-duration storage · Multi-day, thermal and mechanical storage SEE CONNECTIONS →

ANNOUNCED
DEVELOPMENT
PERMITTED
FINANCED
CONSTRUCTION
OPERATING

Power

1.5 MW

Long-duration storage · First commercial

Storage

150 MWh

100-hour duration

Online

Q1 2026

actual

Capital committed

$30M

closed or awarded

Capital pending

—

conditional or under review

ONLINE DATE HISTORY · 1 CHANGE

Nov 9, 2026: none → Q1 2026 · source

How it works

Iron-air

Discharging lets iron pellets rust in air, which releases electricity; charging turns the rust back into iron. Cheap, plentiful materials make 100-hour storage affordable.

OPEN IN 3D →

Capital stack

1 SOURCES

Grant $30M

Grant · California Energy Commission$30M CEC grantAWARDED · 2023-12-13 · utilitydive.com$30M

Milestones

Grid, permits and build

Grid connection, permits, contractors and cost not researched yet for this project.

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Mendocino iron-air battery

Iron-air

Capital stack

Milestones

Grid, permits and build

Mendocino iron-air battery

Iron-air

Capital stack

Milestones

Grid, permits and build

Who buys and who finances

Dependencies

Related

More from Form Energy

Sources