What is Geothermal Power?
Geothermal power production utilizes subsurface hot water or steam created by the heat beneath the earth’s surface to generate electricity.
Heat from the earth’s core in areas of volcanic activity or at the juncture of the earth’s tectonic plates flows naturally toward the cooler surface to form hot springs, geysers, steam vents (fumaroles), and boiling mud pots.
Low temperature geothermal sources can be utilized to heat and cool residential and commercial buildings by installing heat pump systems. High temperature (240° C+) sources can be extracted with standard well drilling technology in the form of hot water or steam to power turbines and produce clean, renewable energy.
Typical geothermal facilities include production and injection wells, a gathering and injection system, a power generation plant, and a transmission line. Wells are drilled using technology similar to those used in the oil and gas industry. The gathering system consists of pipelines that transport the steam or hot water from the wellheads to the generating plant, which uses standard turbine technology. An injection system uses non-productive wells to return process water to the underground reservoir.
Worldwide, the installed generating capacity from geothermal sources is nearly 10,000 MW supplying 60 million people in 24 countries.
Geothermal energy offers several environmental and economic advantages over traditional fossil fuel sources. Geothermal power plants are both “clean” and “green”.
Clean electricity refers to alternative energy technologies such as geothermal that result in a net environmental improvement relative to fossil-fuel based energy production. Green energy is energy from renewable resources through environmentally and socially responsible developments.
Geothermal power plants are also “baseload” power sources meaning they can operate continuously at up to 98% capacity because they have a constant source of “fuel” and require little downtime for maintenance and not affected by changing weather conditions.
From an economic perspective, geothermal energy can be very price competitive. While initial investment is high, lifetime costs are low because the fuel source is free, it is located at the generation plant site (no transportation costs), and it is renewable. Large scale geothermal operations require economic transmission links.
British Columbia’s Potential
BC Hydro has identified 16 prospective geothermal sites in the province, with the six most likely prospects having an estimated geothermal potential of over 1,000 MW collectively.
The best prospect for immediate development in BC is the South Meager Geothermal Project located 55 km north of Pemberton. South Meager, with average temperatures of 260 degrees Centigrade, has been assessed as having a potential generating capacity of up to 100 MW (enough to supply 80,000 homes). Other geothermal prospects include Pebble Creek at North Meager (est. 300–700 MW); Canoe Hot springs near Valemount (est. 50 MW); Mount Cayley near Squamish (est. 20–100 MW); Lakelse Hot Spring east of Prince Rupert (est. 10–50 MW); and Mount Edziza in northwest BC (est. 200–800 MW). All the BC prospects are “hydrothermal” in nature – i.e. hot water rather than steam.
Environmental & Regulatory Considerations
Geothermal projects in BC are subject to the Geothermal Resources Act and a full range of provincial licensing and permitting requirements covering land leases, drilling permits, wildlife protection, public health and safety, environmental monitoring and protection, road construction, and water use. Projects in excess of 50 MW are subject to review under the BC Environmental Assessment Act and Canadian Environmental Assessment Act.
- Land impacts are minimal. Geothermal power plants are typically constructed at or near the geothermal reservoir – there is no need to transport ‘fuel’ to the plant – and require only a few acres.
- Geothermal wells and pipelines may cover a considerable area, but do not prohibit other uses such as farming, livestock, wildlife grazing, and recreational activities.
- Water from a plant’s cooling towers is reinjected to the geothermal reservoir to recharge the reservoir, so there is no release to groundwater and surface water sources.
- Production and injection wells are constructed with casing materials that prevent cross-contamination with groundwater systems.
- Uniquely, the Geysers geothermal reservoir in northern California is recharged by the daily injection of millions of gallons of treated wastewater from two local municipalities.