Greenhouse gas emissions and reservoirs

Impoundment of hydroelectric reservoirs induces decomposition of a small fraction of the flooded biomass (forests, peatlands and other soil types) and an increase in the aquatic wildlife and vegetation in the reservoir.

The result is higher greenhouse gas (GHG) emissions after impoundment, mainly CO2 (carbon dioxide) and a small amount of CH4 (methane).

However, these emissions are temporary and peak two to four years after the reservoir is filled.

During the ensuing decade, CO2 emissions gradually diminish and return to the levels given off by neighboring lakes and rivers.

Hydropower generation, on average, emits 35 times less GHGs than a natural gas generating station and about 70 times less than a coal-fired generating station.

Many years ago, Hydro-Québec decided to make use of the province's water resources to meet the demand for electricity. This policy has contributed greatly to Québec's excellent record on greenhouse gas emissions.

In partnership with universities, research centres and other electric utilities, Hydro-Québec has conducted research on greenhouse gases since 1993.

The objectives of these studies are to:

  • Improve understanding of the impacts of our reservoirs on GHG emissions.
  • Learn about the processes that cause GHG emissions.
  • Monitor changes in GHG emissions in new projects.
  • Compare GHG emissions from hydropower with those from other energy sources.
  • Obtain potential CO2 emissions credits in the future Canadian carbon market.
CO2 flux samples

Specialized documentation

See also