Unlike oil and gas, electricity is not a primary source of energy. It needs to be manufactured from other energy sources.
In Ontario, uranium (55.03%), hydro (21.60%) and coal (8.40%) were the main sources in 2010.  Natural gas, biomass and other alternatives, together with wind, made up the balance (14.92%).  
Ontario produces all of its own electricity needs. See Ontario's production statistics here.
In 2010, production consumed 343,788,800 GJ and emitted 19,690,960 GHG tonnes.