Eastmain-1 Net GHG Emissions Project: The Use of Automated Systems to Measure GHG Emissions from Reservoirs
Hydro-Québec is the largest electric power company in Canada with more than 35 000 MW installed for an annual generation of around 189 TWh. Hydro-Québec owns and operates over 57 powerhouses such as Eastmain-1 that was commissioned in 2005. The growing concern regarding the long-term contribution of freshwater reservoirs to atmospheric greenhouse gases (GHG), led Hydro-Québec, to study net GHG emissions from Eastmain-1 reservoir, which are the emissions related to the creation of a reservoir minus those that would have been emitted or absorbed by the natural systems over a 100-year period. This large study is realized in collaboration with Environnement IIlimité Inc., University du Quebec in Montreal and McGill University.Measurement of GHG fluxes were done with the used of a traditional technique, the floating chambers that measures GHG fluxes at the water-air interface and a new approach using automated systems measuring partial pressure of gas in the water column. Follow up of the CO2 and CH4 fluxes at EM-1 reservoir showed a rapid increase in both CO2 and CH4 emissions the first year after flooding and a rapid return to natural aquatic ecosystems values within 2 and 3 year for CH4 and CO2, respectively. Automated system and floating chambers show similar annual GHG mass balance. Overall GHG emissions from Eastmain-1 reservoir are very low in comparison to thermal power plant of the same capacity.