By Robb M. Stewart

Rio Tinto will invest $1.2 billion to modernize a hydroelectric power plant in Quebec in a bid to secure future aluminum production in the Canadian province.

The money being injected into the Isle-Maligne plant, which was commissioned in 1926 in Alma, Quebec, represents Rio Tinto's largest single investment in its hydroelectric assets since the 1950s.

The mining and metals company said the move will protect its aluminium production in Saguenay--Lac-Saint-Jean for the long term, ensuring a more efficient, safe and reliable power supply of renewable energy to the smelters, casting houses and other facilities.

The aluminum smelters in the Saguenay--Lac-Saint-Jean region are a hub for production of a material used in goods ranging from cans to cars to military aircraft. They also are in the spotlight after foreign-made aluminum became one of the first targets in the Trump administration's trade war, when it and steel were targeted for tariffs that came into effect in March. Much of the aluminum that the U.S. imports is shipped from Canada.

Sebastien Ross, Rio Tinto Aluminium's managing director for atlantic operations, said the company's Isle-Maligne hydroelectric plant has been a strategic asset for 100 years and the investment to modernize its facilities will ensure the long-term future and competitiveness of the Rio Tinto's low-carbon aluminum production in Quebec for decades to come.

The project will run until 2032, and the company estimated that more than 300 people will work on the site at its peak. The investment includes replacing eight turbine-alternator groups, rehabilitating water intake and hydraulic passage, building an extension and mechanical workshop to the north of the power station, replacing electrical and mechanical equipment, and modifying a spillway so that it can be used reliably in winter.

It builds on projects worth a combined $183 million for the refurbishment of so-called butterfly valves and work on two other turbine-alternator groups at the Isle-Maligne power plant.

Rio Tinto is one of Canada's largest private producers of hydroelectricity, with seven hydroelectric facilities located in Quebec and British Columbia that power its aluminum smelters. The company has an eighth power station supplying hydropower to Rio Tinto Iron Ore Co. venture's port operations in Sept-Iles, Quebec.

Write to Robb M. Stewart at robb.stewart@wsj.com

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May 15, 2025 14:50 ET (18:50 GMT)

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