Studies regarding reservoir emissions are often very one dimensional. I say this as someone trained in forest ecology and having been involved in biomass decomposition studies elsewhere in my research life. The premise of increased hydro reservoir GHG emissions is largely based on CH4(methane) production from anaerobic decomposition of forest floor and rangeland biomass that sits on the reservoir bottom once the area is flooded. Indeed CH4 emission sampling from existing reservoirs shows this to be the case in older reservoirs.
However, it is errant to infer solely from studied emission measurement that GHG's are uniformly higher from reservoirs, particularly new ones, like Site C, here's why:
- In almost every respect, reservoir emissions studies ignore the fact that GHG emissions were occurring from the land base prior to flooding, particularly if the area was farm land. Agricultural land, particularly during fallow years, are large GHG emitters from natural decay of vegetative slash/waste etc. If the land was grazing area for cattle the GHG output from animal waste is even higher. When these GHG emissions, which would be there if the dam was not built, are subtracted from the estimated GHG yield of a reservoir, the reservoir output is NOT a large emitter of GHG's, in almost every case.
- In the case of a new dam like Site C, site preparation and clearing of biomass is in fact very intense. Have you seen the site C reserve area? I have. There is virtually no biomass left on site to decompose. You can see the Vegetation Clearing and Debris Management Plan" here: https://www.sitecproject.com/sites/d..._Mgmt_Plan.pdf
- Most emission studies ignore the carbon uptake of the new, developing aquatic ecosystems that develop in stable water bodies.
- further, in the case of reservoirs with site preparation, the rate of GHG production declines very rapidly after a few years as any organic matter is consumed either aerobically or anaerobically
- Site C is about 20X SMALLER than the current Bennett dam reservoir, I can't think of a more efficient area to build a reservoir per KWH/sq unit area.
There is NO credible evidence that Site will be a large GHG emitter, none, at all. In fact, I submit the opposite is true . Site C will be a valuable resource for clean, low emission power and the decision to build it is indeed the best one that could have been made. I suggest in 15 to 20 years time we will be very glad we built it, particularly as we ramp our electric vehicle fleet and produce more power from wind/solar which needs hydro or gas backup.