Imagine if all the oil rigs in Canada suddenly starting drilling for renewable energy.

With high-temperature geothermal energy, it’s possible. “The rig and personnel who drill for oil and gas can be the same rig and personnel who drill for geothermal,” says Alison Thompson, founder and chair of the Canadian Geothermal Energy Association (CanGEA), which now counts 30 companies, including Enbridge and Nexen, as members.

High-temperature geothermal is different from the low-temperature geothermal energy that fuels geo-exchange or geothermal heat pump systems for commercial and residential heating and cooling. Located a few kilometers underground and often visible at the surface as hot springs, this “conventional geothermal” can be used to generate electricity on a large scale. Closed-loop geothermal systems produce virtually no emissions or waste, as all water is re-injected back into the ground to eventually be reheated by the earth.

“This is a huge renewable on the scale of hydro dams,” says Thompson. A 2009 report from the Pembina Institute estimates that 21 billion gigawatt hours of energy are released every year underneath the surface of Alberta, at depths of less than five km.

“Even with the conservative assumption that only 0.5 per cent of this potential is recoverable, it represents more than 1,100 times the current total installed generating capacity in Alberta,” says the report. CanGEA estimates that at least 5,000 megawatts (MW) of high temperature hydrothermal potential are available in B.C., Alberta, and the Yukon, and could power 3.7 million homes.

A January 2009 Credit Suisse report finds that geothermal energy is the least-expensive form of alternative energy at 3.6 cents per kilowatt-hour; cheaper than coal, which costs 5.5 cents per kilowatt-hour (assuming a 1.9 cent/kWh savings from U.S. tax incentives). And it makes sense to produce: forty-year old Nevada-based geothermal company Ormat Technologies is steadily profitable. “Long before Kyoto, geothermal was already making money without incentives,” says Thompson.

Geothermal is “not new, it’s new to Canadians,” Thompson adds. First used to produce electricity in 1904 in Larderello, Italy, geothermal fluids such as the Roman Baths have been used as therapy for hundreds of years. Currently, there are 10,000 MW in operation in 24 countries such as Iceland, Germany, the US, and Mexico—and yes, still in Larderello, Italy. The US is the world’s largest geothermal producer with 3,000 MW installed, powering the equivalent of almost three million homes.