Humans need stable energy supplies that do not harm the Earth. An underutilized source lies beneath our feet.
Geothermal is clean, limitless, predictable, and almost carbon free. But geothermal has no multi-trillion-dollar industry promoting it, nor support from Canadian politicians conditioned to follow established paths. Mostly that means subsidizing fossil fuels.
Heat, through convection and decay of radioactive materials, is transferred toward Earth’s outer crust and comes to the surface in some easily accessible places.
The amount of heat within 10,000 meters (about 33,000 feet) of Earth’s surface contains 50,000 times more energy than all the oil and natural gas resources in the world.
The areas with the highest underground temperatures are in regions with active or geologically young volcanoes. These “hot spots” occur at tectonic plate boundaries or at places where the crust is thin enough to let the heat through. The Pacific Rim, often called the Ring of Fire for its many volcanoes, has many hot spots…
These regions are also seismically active. Earthquakes and magma movement break up the rock covering, allowing water to circulate. As the water rises to the surface, natural hot springs and geysers occur…
Seismically active hotspots are not the only places where geothermal energy can be found. There is a steady supply of milder heat—useful for direct heating purposes—at depths of anywhere from 10 to a few hundred feet below the surface virtually in any location on Earth. Even the ground below your own backyard or local school has enough heat to control the climate in your home or other buildings in the community.
MIT’s climate portal says there is “enough heat flowing from inside the earth to meet total global energy demand twice over” but harnessing it is difficult and expensive. However, the benefits are enticing:
“It’s really the only baseload renewable,” says Jody Robins, a geothermal engineer at the National Renewable Energy Laboratory. Nuclear power (which is carbon-free but not renewable) can serve a similar role, although cost, issues with waste, and public perception have limited its deployment.
Nuclear is a mostly reliable, carbon free energy source. But after more than 75 years of creating waste that will remain radioactive for thousands of years, humans have no risk-free ways to transport and deal permanently with growing piles of spent fuels.
Geothermal offers the prospect of safe, inexhaustible energy. Yet geothermal energy is untapped in most regions of the world, even those that have the greatest potential.
Beyond political and corporate inertia, there are reasons geothermal is a poor stepchild of the energy industry. It is least complicated in particular regions. Iceland for example, because it sits on the Eurasian and North American tectonic plates and has many near-surface hot spots. But Canada has identified areas ripe for development of energy from the earth, mostly in western Canada.
In places where water in injected to improve permeability of the ground — à la oil and gas fracking — a potential concern is induced seismicity. Additionally, heavy demands may be placed on fresh water supplies and pollution may result. To sustain reservoir pressure and steam production, California’s Geysers geothermal project injects tertiary treated effluent from drainage systems in nearby urban areas.
As the cost of wind and solar power has steadily declined and as energy storage systems evolve, investors have been less willing to fund geothermal. In a November 2021 update, the International Energy Agency (IEA) stated:
Electricity generation from geothermal sources increased an estimated 2% year-on-year in 2020, falling below average growth of the previous five years. Geothermal capacity additions averaged 500 MW per year in the last five years, with Turkey, Indonesia and Kenya responsible for most of this growth. These countries are expected to continue to lead, as they have abundant and untapped resource availability.
Nevertheless, geothermal technology is still not on track to reach the required Net Zero 13% generation increases per year over 2021-2030, corresponding to ~3.6 GW of average annual capacity additions. Policies to decrease costs and tackle challenges associated with predevelopment risks are needed to enlarge the deployment of geothermal resources for power generation.
A year ago, inimitable Dave Borlace of Just Have a Think examined the subject. His work is dependable and untainted by commercial interests.
Boise has the largest geothermal system in the country, Idaho Press, 2018
About a third of downtown Boise is heated by geothermal energy, including some of the largest buildings… For all of the 92 buildings and 6 million square feet on the system, it costs the city approximately $1,000 per month total to heat.
Can Geothermal Power Play a Key Role in the Energy Transition?, Yale School of the Environment, December 2020:
Aided by advances in deep-drilling technology for fracking, engineers are developing new methods of tapping into the earth’s limitless underground supplies of heat and steam.
…geothermal has not been viewed as a major feature on the alternative energy landscape.
But a number of experts around the world say that notion is wrong. Thanks especially to the deep-drilling techniques and knowledge about underground formations developed by the oil and gas industry during the fracking boom, a type of geothermal energy called deep geothermal can access hot temperatures in the earth’s mantle as far down as two to three miles...
An 18-member panel assembled by MIT evaluated geothermal systems and found enormous potential for recovery of clean energy. Parts of the world have easily developed hydrothermal resources but the Earth’s deeper, stored thermal energy is present everywhere.
Enhanced geothermal systems (EGS) use heat-mining technology that absorbs stored thermal energy from the Earth. Water is injected into a subsurface fracture zone where it absorbs heat before it is returned to the surface. Heat is extracted to drive turbines that create electricity, and the water is returned to the reservoir. The circulation loop is complete.
MIT noted that people undervalue the long-term potential of geothermal energy. The study stated:
…many attributes of geothermal energy, namely its widespread distribution, base-load dispatchability without storage, small footprint, and low emissions, are desirable for reaching a sustainable energy future.