Trane Energy Services proposes Lake County water battery project

If you live anywhere PG&E strings a wire, you already know the drill.

The project is called FLASHES, which stands for Firemain Linked Auxiliary Supply/Hydraulic Energy Storage. The developer is Trane Energy Services, and the money for the study is coming from PG&E’s Microgrid Incentive Program. The proposal aims to turn everyday gravity and sunlight into a dual-purpose insurance policy against both blackouts and wildfires.

How a Hillside Water Battery Operates

Pumped hydro is about the oldest trick in the energy storage book. The Lake County version uses no dam at all. As Microgrid Knowledge put it, there’s “just two tanks and a hill.” A solar field covering more than 100 acres makes power during the day.

The engineering design balances specific technical parameters across proposed sites:

Project Location	Solar Capacity	Storage Capacity	Water Infrastructure Design
Hidden Valley Lake	20 MW	80 MWh	5-million-gallon dedicated fire reserve upper tank
Hartley and Lucerne	10 MW generators	(Not specified)	Twin 45-million-gallon upper tanks and 90-million-gallon lower tank

The tanks are covered, which keeps the water from evaporating in a county that bakes all summer. But the viability of the entire system depends on a single variable.

The Thousand-Foot Well Dilemma

Developers told the Press Democrat the system could reach more than 1,000 feet down. If the geology down there doesn’t cooperate, none of the rest matters.

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A Municipal Fire Reserve Built for the Ridge

Trane services upgrade and modernize hvac equipment upgrades

For a fire crew it’s a pretty big deal.

Trane Energy Services

Trane expects to know whether the projects pencil out by May or June 2027.

For now, the drilling rigs are turning in the dust of Lake County, probing a hillside to find out whether the sun and the bedrock can finally keep the lights on and the taps running.