Geothermal energy

The Earth’s crust contains a large amount of energy that is radiated from the Earth’s core. This energy is available for use in a variety of ways, including recreational use (hot springs), direct use for heating and cooling, and for power generation.

In Canada, geothermal energy has been tapped to heat homes and businesses for decades. In some cases, communities have taken advantage of naturally occurring hot springs and steam vents to gather hot water and steam for heating. Some commercial hot pools and resorts in Alberta and British Columbia continue to use geothermal energy in this way. The hot springs in Banff, Alberta, is a famous example of the direct use of geothermal heat at a resort.

Today there are two other important emerging geothermal systems in Canada: ground-source heat pumps and underground thermal energy storage systems.

In most parts of Canada, the temperature of the earth at a depth of a metre or two is fairly constant, at between 5° and 12° C throughout the year. This means that the ground is warmer than the outside air in the middle of winter and cooler during mid-summer. Ground-source heat pumps take advantage of this difference. Using a series of buried pipes that circulate a liquid (typically an anti-freeze solution), they use the ground as a source of heat in the winter and as a “sink” to remove heat from the indoor air in the summer.

Currently there are about 30,000 of these systems in homes across Canada. A typical residential system has a heat pump with a capacity of 10 kilowatts, or three tons of refrigeration. In addition, there are about 5,000 systems to heat and cool industrial parks, office buildings, curling rinks, and institutions such as universities and prisons.

A related system, Underground Thermal Energy Storage (UTES), uses underground reservoirs to store heat during the summer and to provide heat during the winter. Where suitable reservoirs are available, UTES can provide significant energy savings. Since the 1980s, this technology has been used by large facilities such as Carleton University in Ottawa and the municipal centre in Scarborough, Ontario.

Other countries, such as the United States, the Philippines, Japan, Iceland and Italy, are major users of geothermal energy for power generation. Geothermal thermal technologies use steam or hot water, at temperatures of more than 100°C, to spin turbines to generate electricity. In Canada, potential sites for geothermal electricity exist in British Columbia, and one project is under development to produce 100 kilowatts as early as 2007.