Geothermal energy is the heat contained within the rock and fluid in the Earth’s crust. It is a source of clean, renewable energy with a small environmental footprint.
Geothermal energy can be used directly to provide heat or indirectly to produce electricity. Direct uses include heat for buildings, agriculture (e.g., greenhouse heating), or industrial uses (e.g., pulp and paper processing). Geothermal energy can also be used on a smaller scale by geoexchange (heat pump) systems, in buildings and homes. The temperature, depth, and location of the resource, as well as whether fluid and permeability are present, determine the ways in which it can be used.
Range of Applications
- High temperature (above 80°C). Electricity generation from steam and very hot water.
- Medium temperature. Waste water treatment, aquatic centres, space heating, cooling systems.
- Low temperature. Heat pump systems.
Only resources which are hotter than 80°C when produced at surface through a well are governed by the Geothermal Resources Act.
Geothermal Power Plants
- Binary Power Plant. Uses geothermal water (120-180°C) and a second (binary) liquid that boils at a lower temperature to spin turbines. Power is generated in a closed loop and releases no emissions. Binary power plants are the most likely to be used in British Columbia.
- Dry Steam Reservoir. Uses produced dry steam (150°C or greater) to spin turbines.
- Hot Water Reservoir. Uses produced hot water (150-370°C) that flashes into steam and spins turbines.
Direct Use Geothermal
Heat used for purposes other than generating electricity is called Direct-Use Geothermal. Medium temperature geothermal energy can be used to provide heat to buildings or for commercial and industrial purposes including: hot spring bathing and health spas; greenhouses; aquaculture; pulp and paper processing; drying lumber, wool or produce; or pasteurization. It can also be used for district heating systems.
Geoexchange systems, also known as "geothermal", "geothermal heat pump" or "ground source" heat pumps, are the most efficient means of heating and cooling a building and providing hot water. The earth's surface under the frost line maintains a nearly constant temperature (10-16°C), remaining warmer than the air above it in the winter and cooler in the summer. Using low temperature geothermal energy, a geoexchange system transfers heat stored in the earth or in ground water into a building during the winter and transfers it back into the ground during the summer.
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