OPG and Northland Power Inc have proposed a first-of-a-kind project for Canada that would develop a pumped storage project at a long inactive, open-pit iron ore mine.

The Marmora Pumped Storage Project is a joint-venture between the two power producers. Located in the Municipality of Marmora and Lake in Ontario, the proposed 400MW closed-loop pumped storage facility could power up to 400,000 homes at peak demand with clean, renewable electricity for up to five hours.

The project design would utilize Marmora’s long inactive iron ore mine, now an artificial lake and local attraction, as the facility’s lower reservoir. The upper reservoir will be created on the site of the mine’s waste rock pile. Repurposing a former mine in this way is a “first” across Canadian power utilities.

If constructed, the facility’s closed-loop design would recirculate water between its two reservoirs to generate electricity. This approach would avoid drawing water from nearby waterways and lakes, eliminating impacts to fisheries and waterway levels.

The 75-acre mine pit, which reaches a depth of more than 200 metres below ground level, was created for mining operations in the mid-20th century and closed in the late 1970s. Since then, the pit has filled with a combination of rain and ground water.