Ground temperatures rising in Canada

According to a new Canadian study, global warming has caused ground temperatures across the country to rise over the past few decades, in some cases by as much as a few degrees. The study is the first comprehensive assessment of Canada's shallow geothermal resources.

The study shows that thermal energy can be harvested with geo-exchange technologies and used for heating homes and buildings during the winter. This is good news for homeowners using Geothermal Heating Systems.

"There was this realization that we had a heat pulse going into the ground and it was a function of climate warming. It's really one of the best records of climate warming there is in Canada," said study co-author Stephen Grasby, a research scientist at the Geological Survey of Canada. "Depending on where you are ground temperature has increased by a few degrees."

"We actually have this opportunity to retrieve that heat energy trapped by global warming, to use that heat that's gone into the ground to offset future use of non-renewable energy sources," says Grasby.

The study, published in the journal Natural Resource Research, assessed ground temperatures across Canada down to 250 meters to get a sense of the potential resource. The researchers found that the heat energy in the first 50 meters alone was roughly equivalent to the commercially recoverable energy in the oil sands. Thats a lot actually, suggesting that if Canadians wanted to invest in Geothermal technology it would be more profitable than the Alberta Oil Sands.

Low-temperature geothermal technologies, often called geo-exchange systems, are capable of efficiently extracting warmth from the ground at shallow depths to heat homes and building. High-temperature geothermal systems tap heat kilometers below the Earth's surface to produce steam that is used to turn turbines and generate electricity.

"It equates to more than 190 million barrels of oil equivalent," said Grasby. He emphasized that the resource is spread out across the entire country, making it impractical to harvest more than a fraction of the total energy potential.

"But even if a small percentage of it is recoverable it's still going to potentially make a marked impact on renewable-energy supply," said Grasby. "Even if you end up with one or two per cent of it, you've still got one or two million barrels equivalent (of oil). It's a big number."

Temperatures typically increase at lower depth, but the researchers found that the temperature differences at 50 meters, 100 meters and 200 meters are getting smaller because shallower depths are heating up.

"The shallow rock mass of Canada has been shown to store a large component of heat due to recent climatic warming," according to the study.

"This suggests that we may have similar heat energy from the upper 50 meters compared to deeper levels depending on the location and relevant recent history (of) surface temperature changes."

The geological survey is working on another study that will attempt to estimate the portion of shallow geothermal resource that's easily recoverable, such as with heat-pump systems. Another study to be published later this year that will estimate the country's potential for generating electricity from geothermal resources at a temperature of 150 degree Celsius and higher.

Alison Thompson, executive director of the Canadian Geothermal Energy Association, said the geological survey studies are welcome and long overdue, but the analysis is based on ground temperature data collected prior to 1985, which is when funding for the federal geothermal energy program was pulled.

Thompson said new data must be collected to get an accurate estimate and to raise the profile of geothermal energy, which despite its massive potential is largely overlooked in Canada as a renewable source of electricity generation.

The geothermal association, which has set the goal of developing 5,000 megawatts of geothermal power projects in Canada by 2015, has identified 33 areas that need to be studied but has found it challenging to raise the required funding to carry out such studies.

"We feel the rest of the country doesn't understand how big this resource is," said Thompson. "For $1 million we could be off and running and really answer all the questions that politicians have. This would be a game-changer for the industry."

Grasby said interest in the area is growing, particularly in Alberta, where the oil and gas industry's drilling and ground-fracturing expertise can be easily applied to geothermal projects. "You just need a regulatory framework to support it," he says.

Canada is the only country located on the Pacific "Ring of Fire" that has NOT developed its high-temperature geothermal resources on a commercial scale. The United States, Japan, China, Russia all have developed their geothermal resources. Many industry experts argue that geothermal could play an important role in reducing natural gas consumption in the oil sands, making it cheaper to get oil out of the tar sands.

The Pembina Institute, a Calgary think tank, released a report in January that estimated there were 21 billion gigawatt-hours of energy released every year below the surface of Alberta at depths of less than 5 kilometres.

"Even with the conservative assumption that only 0.5 per cent of this potential is recoverable, it represents the equivalent of roughly 14 million megawatts of generating capacity," or 1,100 times the current generating capacity of all existing power plants in Alberta, according to the report.

The report cited lack of public awareness as the key barrier to developing the resource.

The geothermal association hopes to raise that awareness level on April 22nd in Vancouver, where it will hold the industry's first major geothermal energy conference in decades. More than 250 people are expected to attend the event, which is timed to coincide with Earth Day.