A technology that generates power by pumping and recirculating water between two reservoirs may soon be in place at an abandoned Ontario iron ore mine.

The technology, known as closed-loop pumped storage, involves two reservoirs, one on top of a hill and another at the bottom, which will recirculate water depending on energy needs. During low-demand periods, the facility will pump water to the top reservoir, and then during high-demand peaks, such as hot summer days, the water will be released to flow through a turbine to the lower reservoir. The technology effectively works as a hydroelectric battery for the province’s electrical grid.

The proposed project is located in an existing iron ore mine, abandoned in 1978, in Marmora and Lake, Ont., around 200 kilometres from Toronto. The project proposes using the open-pit mine as the lower reservoir and a byproduct waste rock pile to the west as the upper reservoir. A final decision on the project is expected after further consultation with First Nations and local townships.

A pumped storage facility in Germany. Photo by Dr. G. Schmitz / Wikimedia Commons (CC BY-SA 3.0)

Canada’s National Observer reached out to several First Nations near the mine but didn’t hear back at the time of publication. However, the project is still in the early beginnings of the consultation process.

The abandoned mine was once a popular summer swimming and cliff-jumping location for nearby residents, NarCity reports.

The project's proponents are Northland Power, a private clean energy producer, and Ontario Power Generation, a Crown corporation. Northland Power declined an interview with Canada’s National Observer at this time.

Pumped storage is not a new technology, but it’s having a moment. Australia, China, Europe and the United States all have several existing pumped storage facilities and are planning dozens more to wean off fossil fuels, the New York Times reports.

The storage facilities often result in a net energy loss, but they ensure grid reliability when demand is high. Energy storage will become increasingly important as Canada transitions to renewable energy powers like solar and wind, a federal government market snapshot said.

A technology that generates power by pumping and recirculating water between two reservoirs may soon be in place at an abandoned iron ore mine. The technology effectively works as a hydroelectric battery for Ontario’s electrical grid.

Canada is lagging behind, with only one operating pumped storage facility in Niagara Region. The 174-megawatt facility pumps water from the Niagara River into a 300-hectare reservoir for energy storage. The capacity of pumped storage facilities is greater than other emerging technologies, such as batteries or hydrogen storage, according to the federal government.

The proposed Marmora project will include a 400-megawatt facility, nearly double the capacity of the Niagara one. There are only three other proposed storage facilities in Canada: two in Alberta and another in Ontario near Georgian Bay.

The Marmora project's target in-service date is 2029, depending on the decision from the Impact Assessment Agency of Canada. The project will “grow into the 2030s with clean, reliable electricity generation and the commitment to the flexible, decarbonized system,” the project description said.

A screenshot from the Marmora Clean Energy Project, which visualizes the closed-loop pumped storage facility. Photo courtesy of Northland Energy

Indigenous consultation is ongoing with several communities and organizations, including the Métis Nation of Ontario, Mohawks of the Bay of Quinte First Nation, the Algonquins of Ontario, Huron-Wendat Nation and Kawartha Nishnawbe Community.

The project description notes engagement is focused on land-use planning, natural heritage interest and archeological interests to determine the preferred water route between both reservoirs.

The Impact Assessment Agency told Canada’s National Observer that cultural heritage resources will be identified through archeological and cultural assessments, and measures will be taken to preserve them during construction. Effects on local waterways during construction and operations will also be mitigated, the agency added.

No traditional land and water use will be impacted, but a direct discharge will likely occur, the project description said. Water sampling of the open-pit mine remains ongoing, as well as the local waterways that would be impacted by discharges.

Matteo Cimellaro / Canada’s National Observer / Local Journalism Initiative

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If the energy required to pumping were to come from the sun and wind, this could be a great project.

Presumably it will all be low cost nighttime power for charging and even if that's baseline nuclear, it's low GHG.