Climate change increasing subsurface temperatures


(Read to the end of this post for an update on studies and events around high-temperature geothermal opportunities in Canada)

The data is old — dating back to 1985 and earlier — but the Geological Survey of Canada is beginning to put together an inventory of geothermal resources across the country. The first study, published online last month in the journal Natural Resources Research, calculated total potential geothermal energy down to 250 metres. One of the most interesting findings, however, was that the temperature gradient wasn’t as steep as historically expected. The reason, the researchers concluded, is that  increases in surface temperature due to global warming was causing the first 50 metres of subsurface to also warm. It means the gap between temperature 50 metres down and temperature 100 metres and 200 metres down has narrowed. (See Toronto Star article here, in which researcher Stephen Grasby says in some locations shallow subsurface temperature has increased by a few degrees Celsius).

They put a positive spin on this finding, suggesting that there’s more thermal energy for home and residential heat-pump systems to tap, and that this energy will displace the use of fossil fuels. Hardly something to cheer about, however, given the initial causes of the warming.

Across Canada, it was found that total potential resource down to 50 metres was the equivalent of 190 million barrels of oil, roughly the size of recoverable oil-sand reserves. Of course, only a small fraction of that could ever be tapped economically because of its distributed nature. But certainly, where there’s population, the renewable resource is there to exploit.

Grasby said another study in the works will estimate likely recoverable shallow geothermal reserves, while a third “EGS” study to be published later this year will estimate total potential high-temperature geothermal reserves down to seven kilometres. But as you’ll read in the Toronto Star article, we’ve got to get some updated data if we are to seriously pursue the geothermal and EGS power generation opportunity in Canada. Funding is needed for the collection of new data from the field and studies must to done to identify high-priority areas for development and to craft the regulatory framework that would support that development.

Alison Thompson, executive director of the Canadian Geothermal Energy Association, told me $1 million in funding would support 30 or so studies that could be turned around in less than six months. Without this kind of up-to-date research it will be difficult to take the industry to the next stage — i.e. project development — because the data will be needed to convince politicians and senior-level bureaucrats that the area is worthy of serious attention and funding.

Just $1 million. It’s not much when compared to the billions being devoted to carbon capture and storage research and development. Funny thing is that geothermal has much more potential to displace natural gas use in the oil sands — and avoid associated GHG emissions — than anything CCS can deliver over the next decade.

BTW: The Canadian Geothermal Energy Association will be holding its first major industry conference in decades on April 22, which is appropriately Earth Day. The buzz or lack of buzz at this conference will be a good barometer of how serious Canadian politicians and industry folk are about pursuing the geothermal opportunity. Stay tuned.

4 thoughts on “Climate change increasing subsurface temperatures”

  1. Apparently this article has drawn a big response at the TORstar website. One point that has been criticized is that the surface air temperature has risen 0.5 degrees since 1990 and the ground temperature has risen 2 degrees (so states this study) and this is a discrepency.

    Are there reasons for this discrepency grounded in science? Lets look at the modes of heat transfer, convection, conduction and radiation. The sun radiates heat to the earth and it absorbed and scattered by gases in the atmosphere and the surface air. It is also absorbed by the solid earth.

    Earth is a solid mass and the air is a gas. Solid objects absorb and retain heat much more effectively than gases. This is why energy efficient homes and buildings utilize thermal mass (concrete or stone fixtures). The temperature of the thermal mass becomes warmer than the ambient air around it and therefore radiate this excess heat to the indoor space.

  2. One notable contradiction is that if the earth is warmer than the air above it; the air temperatures should eventually reflect that change. There is maybe a delay because the earth would release this extra heat slowly. Maybe the temperature differences between the earth and the air reflects this delay.

  3. Geothermal seems to be one of the cheapest options available and yet it gets very little press. A function of lobby economics no doubt.

    If it would really cost just $1 million, surely a power company would be happy to fund it, in return for a first look at all the data. That has to be an investment worth making.

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