Green Power - A Consumer Guide to Green Power in Canada

WHAT TO KNOW

What are Green Power Technologies?

WATER

Waterpower can be a very efficient and clean source of electricity. There are several technologies for converting the energy of moving water into electrical power. Large, medium and small-scale hydroelectric facilities have been important components of the energy systems of Canada and many other countries for generations. Ocean energy technologies, such as tide and wave powered generating stations, are more recent innovations.

Hydroelectricity

Size and environmental impact are the two criteria that most often differentiate Green Power hydroelectric facilities from traditional hydro projects. Both large and small-scale hydroelectric plants generate electricity by using falling water to turn a turbine connected to a generator. Size is a criteria because small hydropower facilities (usually less than about 20-25 MW), if well-designed and well-located, can have minimal impact on the environment.

As a general rule, hydroelectric plants using dams to store water in reservoirs have a larger environmental impact than run-of-river facilities. This is because dams can flood environmentally sensitive areas, destroy or alter fish and wildlife habitat and migration routes, and force communities to relocate. Some small-scale hydroelectric plants rely on low dams, weirs or diversions, but do not cause substantial flooding. Run-of-river projects, as their name suggests, divert water through the generating station and then back into the river without appreciably altering natural flow rates or water levels.

While most large hydropower facilities have dams and reservoirs, there are some very large-scale run-of-river hydro facilities, such as Ontario Power Generation's huge Sir Adam Beck generating station at Niagara Falls.

Tides and Waves

There are currently only about 40 places in the world suitable for tidal generating stations. That's because there must be a difference of at least five metres between high and low tides for a tidal generator to create cost-effective electricity. Canada's 20 megawatt Annapolis Tidal Generating Station in Nova Scotia is one of three tidal facilities currently operating worldwide. The Annapolis Basin opens into the Bay of Fundy, which has the highest tides in the world.

Wave energy generators are being developed worldwide, and are able to extract energy from the up and down movement of waves. The first demonstration projects are expected in 2006.