Advocates of so-called alternative energy sources promote them to diminish, if not eliminate the demonized molecule, carbon dioxide, ‘CO2’. Yet they rarely mention geothermal energy as a plausible alternative. It may be because, like most others, it is a disappointment and cannot provide a viable substitute for reliable, cheap fossil fuels.
Geothermal energy is energy generated by the earth itself; from the heat of the Earth’s core rising through crustal fissures. One variety of such energy has been used for decades: geysers and hot springs, upwellings of water heated close to the planet’s surface.
A second variety of geothermal energy has only relatively recently been developed. In this approach, equipment drills to hot depths, usually in thinner parts of the Earth’s crust. Further, pipes are inserted to bring water or another fluid downhole to be heated, and then the fluid returns to the surface to a heat exchanger, finally propelling an electric turbine.
New technology, electrical resistivity tomography, ‘ERT’, developed by the Pacific Northwest National Laboratory, enables more accurate mapping of high potential drilling zones. However, its proponents admit that drilling itself remains relatively expensive. The deeper the well, the higher the temperatures encountered. As the amount of harvestable energy increases, so do the associated expenses and problems.
As the Journal of Petroleum Technology noted, oil and gas wells cost millions of dollars. So do geothermal wells. However, these wells must usually be drilled several hundred metres deeper than oil and gas ones. Deep drilling brings complications from the higher heat encountered, according to GeoDrilling International. Although there are new still-experimental techniques that may lower costs, they remain unproven.
The major cost for deep heat geothermal installations is more than that of deep wells. The Canadian federal government estimates that the capacity cost per kilowatt-hour (kWh) is C$6,207 to C$8,345, which is currently more than conventional (i.e., coal- or gas-fired) or solar electric power but less than nuclear (however, nuclear has lower cash operating costs than fossil fuels).
Therefore, it is unclear whether geothermal could be superior to other energy forms, even if CO2 emission mitigation is crucial. With CO2 emissions included from well drilling, equipment manufacturing, and the construction and outfitting of the generating plant and transmission lines, the supposed benefit would be reduced.
The federal study claims the ‘levelized [wholesale] cost’ is less than conventional electric power, ranging from C$77 to C$128 per megawatt-hour (MWh). The levelized cost has been misleading in the cases of solar and wind power. It ignores the intermittency of those energy forms. In 2023, Canadian retail power averaged C$0.11 per kWh, or C$110/MWh, i.e., less than C$128.
Conceptually, geothermal energy should be more reliable than the other two ‘green’ energy sources, but it is uncertain if the available heat will be as long lived as forecast.
Regarding total global geothermal power capacity, a 2013 World Energy Council paper noted that estimates of practical potential geothermal power range from 35-70 gigawatts (GW) in a 2003 study to 210 GW in a 2005 study. The latter study concluded that just 8.3 percent of world power needs could be met by geothermal electricity. While adding geothermal might be a good diversification of energy sources, it is unlikely that it could substantially replace conventional energy.
Ian Madsen is the Senior Policy Analyst at the Frontier Centre for Public Policy.
