Words to know
electricity supply mix
The share of electricity that comes from each source, such as nuclear, hydro, gas, wind and solar.
clean energy
Energy produced with little or no greenhouse gas emissions or air pollution, such as hydro, nuclear, wind and solar.
baseload
The minimum amount of electricity needed all the time, usually supplied by steady sources like nuclear and large hydro.
intermittent
Starting and stopping, or rising and falling. Wind and solar power are intermittent.
energy storage
Ways to save energy for later, such as batteries or pumping water uphill into a reservoir.
greenhouse gas
A gas, such as carbon dioxide or methane, that traps heat in the atmosphere and contributes to climate change.
small modular reactor (SMR)
A nuclear reactor that is smaller than traditional reactors, designed to be built in factory-made sections.
transmission line
A high-voltage power line that carries electricity long distances.
Hook: flip the switch
When you turn on a light in Ontario, where does the electricity come from? For most Ontarians the honest answer is: a little bit of everything, but mostly uranium and falling water. In British Columbia or Quebec, it is mostly falling water. In Alberta, it is mostly natural gas. Each province's mix tells a story about its physical geography.
Fossil fuels
Canada is a major producer of oil and natural gas. Natural Resources Canada reports that Canada has the third-largest proven oil reserves in the world, and almost all of it is in Alberta's oil sands. Natural gas comes mostly from Alberta and northeastern British Columbia.
Fossil fuels are energy-dense and easy to store and transport, which is why they power most vehicles, heat many homes and run industries. But burning them releases greenhouse gases and air pollutants. Ontario stopped burning coal for electricity in 2014, when its last coal-fired generating station stopped using coal. Today, Ontario uses natural gas plants mainly to meet peaks in demand and to back up other sources.
Clean energy: location decides the method
Hydroelectricity needs a large river and a drop in height. Water stored behind a dam (or flowing through a run-of-river station) spins turbines. Provinces with big rivers flowing off mountains or the Canadian Shield (British Columbia, Manitoba, Quebec, Newfoundland and Labrador) rely heavily on hydro. Ontario's waterpower includes stations at Niagara Falls. Large dams can flood land, change fish habitat, and release mercury from flooded soils into the food chain, which has affected First Nations and Inuit who rely on fish. The James Bay and Northern Quebec Agreement (1975), signed with the Cree and Inuit of northern Quebec after a large hydro project began, was Canada's first modern land claim agreement.
Nuclear power splits uranium atoms to make heat, which makes steam to spin turbines. Canada's uranium is mined in the Athabasca Basin of northern Saskatchewan, and Canada designed its own reactor type, the CANDU. Ontario has three nuclear generating stations: Bruce (on Lake Huron), Darlington and Pickering (on Lake Ontario). They are beside large lakes because they need lots of cooling water. Nuclear power produces no greenhouse gases while operating and runs steadily (baseload), but used fuel stays radioactive for a very long time. In 2024 the Nuclear Waste Management Organization chose an area in northwestern Ontario, the Wabigoon Lake Ojibway Nation-Ignace area, as the site for a deep underground repository, with both communities having agreed to host it. Ontario Power Generation is also building small modular reactors at the Darlington site.
Wind power needs strong, steady wind: open Prairie land, shorelines such as those of Lake Huron and Lake Erie, and places like the Gaspé Peninsula in Quebec. It is a flow resource with no fuel cost, but it is intermittent, needs large areas (though farming can continue between turbines), and turbines must be sited to reduce harm to birds and bats.
Solar power works best where there are many sunny days. Southern Alberta and Saskatchewan are among the sunniest places in Canada. Solar panels can go on rooftops, so they can be close to users. Output drops at night and in winter, which is why energy storage (batteries) is becoming important.