What is geothermal energy?

Geothermal energy is derived from the natural heat within the Earth (from the Greek words geo for earth and therme for heat). Most of the geothermal energy available to Canadians occurs at fairly low temperatures, ranging from about 5° to 12° Celsius a metre or two below the surface and up to 250° C or more at a depth of several kilometres. The insulating properties of soil and rock, and the energy-transporting properties of water, play key roles in using geothermal energy.

Geothermal energy resources are generally classified according to temperature. High-temperature resources are used for steam and electricity production, medium-temperature for direct space heating and industrial processes, and low-temperature for indirect use with heat pumps.

Low-temperature, near-surface warmth is a free, renewable energy source available across Canada, and it can be used for heating and cooling almost any type of building. More than 35,000 “earth energy” or “geo-exchange” systems are already in use. Experts expect that many thousands more will be installed in the near future. There has been some use of medium-temperature resources for space heating in British Columbia and Nova Scotia. Deeper, higher-temperature geothermal resources that could be used to produce electricity are found mainly in British Columbia. There are no geothermal electric projects operating in Canada at present, but one B.C. project is under development.

Although geothermal energy has only recently gained prominence in Canada as a way to reduce energy costs and greenhouse gas emissions, it is by no means a new technology. Prehistoric people used geothermal energy when they lived in caves, which provided winter warmth and summer cooling. Long before explorers and settlers arrived, Aboriginal people often gathered at hot springs in Western Canada. As early as 1886, hot water was piped from hot springs to hotels and spas in Banff, Alberta. High-temperature geothermal energy has been used to generate electricity in Italy since 1904, and today at least 21 countries from Japan to Iceland use geothermal energy to generate electricity. In addition, 58 countries use this energy directly for purposes such as heating residential and commercial districts.