A new company affiliated with Cianbro, one of Maine’s largest construction firms, is in the preliminary stages of developing a $1 billion pumped storage hydropower project in Oxford County.

Western Maine Energy Storage, a company established in May 2024 and operating out of Cianbro Corp.’s Pittsfield headquarters, submitted its application for a preliminary permit to federal regulators on July 21.

The project, to be located near Dixfield, would be the first of its kind in Maine and among the largest in the Northeast, capable of generating about 500 megawatts of on-demand power. The project would use two 100-acre artificial reservoirs to store and release water for electricity generation during peak demand.

According to the application, the developer estimates annual energy output at 1 million megawatt hours; for reference, Maine uses a little more than 11 million megawatt hours of electricity a year.

Pumped storage hydropower is a large-scale energy storage system that operates similarly to a battery — water is pumped from the lower reservoir into the upper reservoir when demand on the electrical grid is low. When demand on the grid is high, water is released from the upper reservoir through turbines into the lower reservoir to generate electricity.

The project would join just two major pumped storage facilities in the Northeast — the 1,140-megawatt Northfield Mountain project in Northfield, Massachusetts, and the 1,160-megawatt Blenheim-Gilboa project in Gilboa, New York. Both were built in the 1970s and continue to operate, supplementing their local grids.

Most pumped-storage projects in the U.S. were built in the 1970s. According to the U.S. Energy Information Administration, nearly half of the pumped storage capacity still in use came online in that decade.

At the time of the last inventory in 2018, the U.S. had 22.9 gigawatts of pumped storage generating capacity, compared with 79.9 gigawatts of conventional hydropower of the kind seen frequently in Maine.

Recent research from the National Renewable Energy Laboratory found that the creation and use of pumped storage hydropower can have some of the lowest greenhouse gas impacts of any form of energy storage.

The proposed project would initially use water from the Androscoggin River and later rely on precipitation and runoff to replenish the reservoirs.

The project’s location on previously logged lands near existing roads and Central Maine Power’s transmission corridor will limit environmental impact, according to Western Maine Energy Storage’s website. This means no new long-distance transmission lines would be required.

Western Maine Energy Storage’s preliminary permit allows the developers a four-year window to conduct environmental, engineering and cultural studies, notably extensive environmental fieldwork, projected to last through 2027, which will include studies of wetlands, protected species, groundwater and cultural resources.

Under FERC regulations, preliminary permits allow permit holders to maintain priority as the first applicant for a license while studies are underway. However, the permit, just the first among many, does not authorize construction.

Permitting and federal licensing may begin in 2026 with construction beginning in 2029 and potentially lasting through 2033. In the meantime, Western Maine Energy Storage will conduct feasibility studies, environmental reviews and community outreach over the next few years.

Parties with comments, motions to intervene, notices of intent and competing applications have 60 days to submit paperwork, according to FERC regulations.

Ferg Lea, of the Androscoggin River Watershed Council, said his organization has not yet reviewed the developer’s permit application so he could not speak to any effects the project may have on the river and surrounding habitats.

The developer’s application lists Canton, Dixfield, Jay, Livermore, Livermore Falls, Mexico, Peru and Rumford as nearby towns that may have an interest in the project or might be affected by it. Municipalities and environmental groups may file to intervene to become a formal party in the proceeding.

In an email to the Sun Journal, Dixfield Town Manager Alicia Conn confirmed that a representative from the Western Maine Energy Storage had reached out earlier this summer. Conn also said she could not speak yet to how the project may affect the town as the developer is scheduled to present the project for the first time before the Select Board on Aug. 11.

Western Maine Energy Storage expects to file a draft license application by the third year of the permit. The developer plans to follow up with a final application in the last year of the permit.

A representative from Western Maine Energy Storage was not available for comment.