This previous post on Canada’s new commitment to generate 90% of its electricity from sources that do not emit greenhouse gasses by 2020 was a bit too wide-ranging, since it sought to consider all possible mixes that satisfied the 90% criterion. A more reasonable approach is to consider two plausible scenarios.
In the first scenario, electricity demand rises by 10%. Assuming that means 10% more generating capacity is required, that means increasing Canada’s electrical capacity to 132 gigawatts. Doing so while achieving the 90% target would mean scrapping 20.4 gigawatts of emitting capacity (about three times the capacity of all of Ontario’s coal plants) and building 32.4 gigawatts of non-emitting capacity (six giant dams or about thirty five nuclear reactors).
In the second scenario, energetic conservation efforts cause demand to fall by 10%. As such, we would be able to cut our total generating capacity to 99 gigawatts. Producing that while reaching the 90% target would mean scrapping 23.1 gigawatts of emitting capacity (3.5 times Ontario’s coal plants) and building 23.1 gigawatts of non-emitting capacity (under five giant dams, or about twenty five nuclear reactors).
The numbers might work out a bit differently if you did the calculations based on terawatt-hours of electricity use, rather than gigawatts of installed capacity.