CONFIRMING THE C FOOTPRINT OF THE PAIX DES BRAVES (EASTMAIN 1) RESERVOIR 17 YEARS AFTER FLOODING

In the early 2000s, Hydro-Québec launched extensive research in the Paix des Braves reservoir watershed to study greenhouse gases (GHG) emissions at an integrative scale. This study presents the long-term GHG monitoring results for the reservoir and surrounding lakes. Diffusive emissions were measured directly on the reservoir during ice-free season and allowed to validate estimates obtained through gas concentration measurements made all year round using automated systems installed in the Eastmain-1 generating station. Degassing emissions were also calculated owing to this monitoring made in the water going through the turbines. The results indicate that despite a significant decrease in CO₂ dissolved concentration and emissions a few years after impoundment, CO₂ diffusive emissions still represented 90 % of the total emissions in CO₂eq in the 2018-2022 period. Despite a high spatial and temporal variability, CH₄ emissions represented only a small fraction of the total gross emissions (< 6.8 %). Total net reservoir emissions after 17 years are in the order of 438۰10³ tCO₂eq/yr, very close to the prediction made in 2012. Accordingly, current generation efficiency represents 76 gCO₂eq/kWh, number that could be further discussed considering natural CO₂ emissions that should not be attributable to the reservoir. The study confirms that hydropower in Quebec has a low carbon footprint.

Primary Presenter: François Bilodeau, Hydro-Quebec (bilodeau.francois@hydro.qc.ca)

Authors:

François Bilodeau, Hydro-Quebec  (bilodeau.francois@hydro.qc.ca)

Maud Demarty, Aqua-Consult  (maud.demarty@aquaconsult.ca)

Charles Deblois, Aqua-Consult  (charles.deblois@aquaconsult.ca)

Alain Tremblay, Hydro-Quebec  (tremblay.alain@hydroquebec.com)

Paul Del Giorgio, UQAM  (del_giorgio.paul@uqam.ca)

Yann Chavaillaz, Hydro-Quebec  (chavaillaz.yann@hydroquebec.com)