Canadian Geothermal Power Prospects
The west coast of Canada is part of the pacific ring of fire, an extremely active tectonic margin that encircles the Pacific Ocean. As the pacific ring is characterized by active volcanic zones, a dozen young volcanic edifices and more than one hundred hot springs are present in British Columbia and the Yukon. These features provide evidence for the presence of substantial high-grade geothermal power resources, the total power of which is estimated at 3000 to 5000 MWe. Roughly half of this resource is located in remote areas which could make geothermal development impractical due to the absence of infrastructure and power lines. On the other hand, the other half of this resource is potentially attainable, and in fact, many geothermal power exploration projects are currently ongoing in BC (and to a lesser extent, the Yukon and the Northwest Territories).
In BC, regulations specific to geothermal power exploration and production are in place, making this province unique to the country. Geothermal permits are granted by the Provincial Government through public tenders and are valid for a maximum of 8 years. After confirming the resource, a permit can then be converted to a long-term lease for power generation. One geothermal lease exists in the Province as of yet in the South Meager Creek area, and four geothermal permits are in place in North Meager Creek and the Rockies.
Investigation at South Meager Creek first began in the 1970’s with various techniques such as geology, geochemistry, geophysics, and the drilling of many wells. During 2001 and 2002, a magneto-telluric (“MT”) geophysical survey provided strong evidence for the presence of a large, high temperature geothermal reservoir at a relatively shallow depth. As follow-up, Western GeoPower conducted further drilling 2 years later to confirm the resource; results from one well demonstrated a maxiumum down-hole temperature of 260°C at a depth of 2632 meters.
Wellbore simulation carried out by GeothermEx on a second well (MC-8) indicated that the well would be commercial. A flow test of the well in September 2008 demonstrated potentially commercial permeability in the reservoir, but MC-8 itself did not sustain self-flow. However, wellbore simulation indicated that a well targeting the same permeable zone from a lower elevation could flow at the equivalent of more than 6 megawatts of electrical output. The results of the exploration work completed to date strongly indicate the presence of a geothermal reservoir with an area extent of 4.5 to 7.5 km and an average temperature of 220 to 240°C, with a maximum measured temperature of 275°C. These attributes identify the South Meager field as a “high temperature” field (defined as one with 200°C or higher temperature) and a major geothermal site (defined as a site with 100 MW or more of potential development capacity).
Pebble Creek, or North Meager, consists of three geothermal permits in the North of the Meager Creek Volcanic Complex. Old temperature data from decades ago was recently integrated into a GIS database consisting of the most recent geological, geochemical and topographic data. Temperature models were then created to delineate the geothermal up-flow zone and to assess the extent of the high-enthalpy reservoir, accessible from the permit areas. Temperature gradient models were extrapolated to a depth of 3000 meters, and the extent of the high enthalpy zones is estimated to be at least 10 square kilometers. The total high-grade heat energy convertible to power is conservatively estimated above 55 million Megawatt hours of electricity, which can support a 230 MWe generating capacity for 30 years.
Another promising geothermal development project in BC, a current geothermal permit area, is the Canoe hot springs where temperatures reach 70°C to 80°C – among the highest temperature for hot springs in BC. Geochemical thermometers indicate that deep undiluted geothermal waters under the property may reach above 200°C; data on these springs suggest the presence of large temperature geothermal fluids at depth which can be used for power generation. Furthermore, because the project is roughly 7 km away from a subtstation on the BC Hydro power grid, the resource is commercially viable for power generation using binary generation or large-scale flash steam technology.
The Peace Region in the north east of BC also shows promise in terms of its geothermal resource; temperature data from oil and gas wells in this area indicate the presence of a significant geothermal anomaly.The average measured temperature gradient for the Clarke Lake gas field is 54ºC/km, suggesting that the area has a significant potential for commercial geothermal power generation. Furthermore, the proximity of the area to power lines (and Alberta power market) enhances the economics of a geothermal power project in the region that could provide energy to near-by communities, particularly Fort Nelson.
Other areas under study for geothermal power generation include western Yukon, in the Wrangell volcanic belt, and the Fort Simpson area in the North West Territories. Based on the limited available volcanological data, it is estimated that a total of 500 to 1500 MW geothermal power capacity may be present in the entire Yukon Territory. As for the North West Territories, the field data, combined with regional geophysical information, provide strong indications that the Fort Simpson area is located on a positive geothermal anomaly with temperature gradients above 50°C.
Link to full article:
Ghomshei, Mory. April, 2010.