“Water Battery” proposed in western Maine

Pumped storage hydropower could be coming to Maine. In July, Western Maine Energy Storage filed for a preliminary permit from the Federal Energy Regulatory Commission (FERC) for a proposed development near the Central Maine Power transmission corridor. The project would be mostly in Dixfield, with a small portion in Canton, in Oxford County.

The FERC permit, which will secure the site for further studies including economic and environmental feasibility, is the first step in a permitting process that will take years.

Western Maine Energy Storage was established by the Pittsfield-based Cianbro Corporation in May 2024 to spearhead the “water battery,” shorthand for the two-reservoir system that involves pumping and storing water to meet the grid’s energy needs.

A primary goal of the project is to boost resilience by putting power onto the grid at times when other renewable resources, like wind and solar, aren’t generating electricity. A prime example of this is during evening hours after the sun has set, when energy demand, also known as the load curve, tends to peak.

“We all do appreciate the renewables on the grid, but they can’t always supply the energy electricity that we need. So a project of this nature will help stabilize that supply,” said Lauren Walsh, Cianbro’s corporate environmental manager.

The proposed 500 megawatt project would be the state’s first and only the fourth such energy development in New England. Two pumped storage hydropower plants have operated in Western Massachusetts for decades, and Connecticut has a smaller facility that’s been in operation since the late 1920s. There are a handful of such projects around the country, according to FERC data.  

How does pumped storage hydropower work?

In order to function, pumped storage hydropower relies on differences in elevation in order for water to flow between two artificial reservoirs.

Oxford County’s topography makes the chosen location a match for the proposed development. Western Maine Energy Storage plans to build an upper and lower reservoir, each at 100 acres in size. The two reservoirs will be connected by a pipe. A powerhouse sitting just above the lower reservoir will generate electricity whenever water flows down from the upper reservoir and passes through a turbine. That electricity can then be passed onto the grid.

“When power is relatively cheap, you pump water up, and then when it gets really expensive, or there’s a lack of juice in the system, you flow it back down,” said Tom Brennan, director of public affairs with Western Maine Energy Storage.