Green Power - A Consumer Guide to Green Power in Canada

WHAT TO KNOW

What are Green Power Technologies?

OTHER TECHNOLOGIES

Although the following renewable energy technologies are currently not used extensively in Canada, they do have the potential to support a greener electricity supply mix, through the use of Green Power or by lowering demand for electricity from the public grid. Research and development will continue to improve the viability and cost-effectiveness of these technologies.

Geothermal

Although the Earth's surface is cool, the temperature at its centre is several thousand degrees. By drilling deep boreholes, scientists have measured how temperature increases with depth at various locations around the world. This "geothermal gradient" is not uniform, and in places where temperature increases more rapidly this heat can be used to generate electricity and to heat the air and water in buildings. Geothermal resources are classified according to temperature. High-grade resources (higher than 150°C) are commonly associated with recent volcanic areas and can be tapped to generate electricity. Medium-grade (90-150°C) and low-grade (less than 90°C) resources can be used most economically to provide seasonal energy for heating and cooling.

Meager Creek, a volcanic area 150km north of Vancouver, is a geothermal site that is under active study in Canada. Western GeoPower Corp. is currently moving ahead with plans to bring hot water to the surface to drive steam turbines and generate electricity at this site.

Heat Pumps

The energy stored in the Earth can also be used to heat and cool houses and commercial buildings using a Geothermal Heat Pump (GHP) system. This can displace the need for conventional electricity, where it is being used for heating and cooling. Also known as ground source or water source heat pumps, GHP systems use a network of underground (or underwater) pipes to transfer heat from the warmer earth (or water source) to heat the building in winter. In summer, the system is reversed to cool the building. GHP systems can be installed almost anywhere and, according to the US Environmental Protection Agency, can be the most efficient, clean and cost-effective space conditioning systems available. For more information, see www.earthenergy.ca.

Deep Lake Water Cooling

Enwave operates a district heating system in Toronto's commercial core. This technology pumps cold water from deep in Lake Ontario to air-condition buildings in summer. Because the system's closed-loop design operates in conjunction with the city's water system, no additional water is drawn from the lake to cool the buildings. The system cools the buildings more efficiently than the large industrial chillers currently used at individual buildings at a fraction of the energy expenditure. This displaces the need for conventional electricity, where it was being used for cooling the buildings.

Fuel Cells

Fuel cell technology is the subject of considerable research and development in the field of automotive power, as well as commercial and residential electrical power generation. Fuel cells convert chemical energy to direct current (DC) electrical energy with relatively high efficiency by chemically combining a fuel (normally hydrogen) and an oxidant (air) without burning. The electricity can be used by DC motors, computers, lights and other appliances, or it can be converted to alternating current (AC) for typical commercial and residential applications. Fuel cells themselves are compact, quiet and non-polluting. Among the fuel cells being developed today are utility-scale units that could provide a new option for generating cost-competitive grid power. Smaller units, some scaled to residential size, are already available. Very small fuel cell units are now finding their way into the computer and cell phone industries, replacing conventional batteries.

The biggest cloud hanging over fuel cell technology is the amount of energy required to produce the hydrogen. Hydrogen does not occur freely in nature and must be produced, either by extracting it from other fuels, such as natural gas, or by running an electrical current through water to produce bubbles of hydrogen in a process called electrolysis. The process only qualifies as Green Power if a low-impact renewable energy source is used to produce the hydrogen.