Quebec's Top 10 Industrial Greenhouse Gas Emitters
In 2024, ten industrial facilities emitted 51 % of all GHGs covered by Quebec's carbon market. Leading the ranking: the Port-Daniel cement plant, whose emissions match the entire city of Trois-Rivieres.
Top 10 emitters in 2024 (t CO₂eq)
A ranking dominated by cement, refining, and aluminium
The Cimenterie de Port-Daniel, operated by St. Marys Cement in Quebec's Gaspe Peninsula, is the province's single largest industrial polluter with 1.31 million tonnes of CO2 equivalent in 2024. That is the equivalent of the annual emissions from a city of roughly 150,000 people - approximately the size of Trois-Rivieres[2]. Inaugurated in 2017[3], the plant quickly established itself as Quebec's top industrial emitter.
Behind it, Quebec's two major oil refineries come in nearly tied: the Jean-Gaulin Refinery (Energie Valero) in Levis (1.22 million tonnes) and the Suncor Refinery in Montreal-Est (1.22 million tonnes). Together, the two refineries account for 2.44 million tonnes, or 12.7 % of the industrial total.
Aluminium is the most represented sector in the top 10, with three smelters: Aluminerie Alouette in Sept-Iles (1.1 Mt), Rio Tinto Alcan in Alma (876,000 t), and Aluminerie de Becancour (831,000 t). Together, these three plants emit nearly 2.8 million tonnes - 14.6 % of the total - despite relying on hydroelectric power for smelting. Emissions stem primarily from carbon anodes consumed in the electrolysis cells.
ArcelorMittal, Rio Tinto, and the steel and titanium sector
ArcelorMittal appears twice in the ranking: its steel complex at Contrecoeur-Est (971,000 t) and its Port-Cartier pelletizing plant (752,000 t). The latter processes iron ore mined on the North Shore into iron pellets for the steel market[4].
Rio Tinto also features twice - through Rio Tinto Alcan in Alma and through its Sorel-Tracy metallurgical complex (Rio Tinto Fer et Titane, 758,000 t), where ilmenite ore is refined into titanium dioxide and pig iron[5].
Rounding out the top 10, Ciment Quebec inc. emits 749,000 tonnes. The two cement plants combined - Port-Daniel and Ciment Quebec - total over 2 million tonnes, or 10.7 % of the industrial total: a heavy footprint for just two facilities.
The regulatory context: Quebec's carbon market (RSPEDE)
These emissions are reported under Quebec's cap-and-trade system for greenhouse gas emissions (RSPEDE), which requires any facility emitting 25,000 tonnes or more per year to purchase emission rights[6]. Jointly administered with California since 2014[6], this carbon market is one of the cornerstones of Quebec's climate policy.
Quebec's target is to reduce its emissions by 37.5 % below 1990 levels by 2035[7]. Large industrial emitters are central to this goal: in 2024, the facilities covered by the RSPEDE collectively emitted 19.2 million tonnes - relatively stable since 2013 (18.4 Mt), despite a notable spike in 2021-2022.
What the data does not cover
The RSPEDE excludes small emitters (below 25,000 t/year), the transportation sector (which accounts for more than 44 % of Quebec's total emissions[8]), buildings, and agriculture. The 19 million tonnes counted here represent roughly 24 % of the 78 million tonnes emitted annually across Quebec's entire economy[8].
The reported figures also cover only direct (Scope 1) emissions. Gasoline combustion from fuel produced at the refineries, for example, is not counted here - it is attributed at the point of use, in the transportation sector. This distinction matters when interpreting the refineries' ranking.