From our home on the earth's thin crust, it's hard to believe that 99.9% of the earth's volume is hot enough to boil water. Atomic decay inside of the earth heats its molten core to a temperature that is hotter than the surface of the sun! To harness this geothermal power, we need only drill through the crust and use that heat to boil water to drive turbine generators. This water can be reinjected into the earth in a closed loop.
The world's first geothermal power plant was built in Larderello, Italy in 1911. It is still producing enough power for a million homes today. Geothermal power already supplies 26% of electrical power in Iceland and the Philippines and 5% of California's at prices that are competitive with coal power. Geothermal power plants run 24 hours a day with an uptime of over 90%. They require no fuel and produce no pollution. Coal and atomic power plants need much more maintenance downtime, so they only operate an average of 75% and 65% of the time. Wind and solar power are even worse, producing an average of only 30% and 24% of their rated power.
Why then, do we use coal to produce most of our power? We dig thousands of miles of tunnels or blast the tops off of mountains and ship the coal thousands of miles just to burn it to make steam. Every step of this process is an environmental nightmare so bad that we have ruined the earth and upset the entire climate balance of our planet. Acid rain has killed our forests and coral reefs and mercury emissions have made it dangerous to eat most fish.
We started burning coal because it was easy at first. The environmental problems didn't become apparent until the scale of coal burning became massive. Coal became big business with lots of political clout that squeezed out all competitors including geothermal. Energy policy today spends billions to subsidize coal and develop "clean coal" technology but nothing at all on geothermal development. The fossil fuel Juggernaut tramples all alternatives that threaten the status quo.
Geothermal power today is mostly done in natural geyser or hot spring areas where underground water in contact with hot rocks below produces steam near the surface. However, deep drilling methods developed by the oil industry make is theoretically possible to build geothermal plants in places where the earth's crust is deeper, like the eastern United States. Old oil wells are often rehabilitated by drilling another hole nearby and injecting water to push the oil out. The mixture of oil and water that comes out is very hot. This hot water is now considered a nuisance but if it's heat were used to generate power, tens of thousands of megawatts (MW) could be generated in Texas alone with a cost payoff of only three years.
A recent MIT report studies the potential of similarly injecting water into hot rocks purely for the purpose of generating power in non-thermal areas like the Eastern U.S. The report concludes that hot rocks are a rich resource that should be developed now. The research cost of such a development would be much less than the billions already being spent on "clean coal" and nuclear power. Since the water used is recirculated back into the ground, geothermal power consumes a tiny fraction of the massive water consumption of a coal or atomic power plant.
Atlantic Geothermal has a very ambitious plan using tunneling technology similar to that used to construct the tunnel under Mont Blanc to build a 50 foot wide tunnel 80 miles long and three deep. Using 1500 ft. boreholes laterally to expand the heat extraction field, the system could generate 1600 MW of power, nearly matching the output of Hoover dam. Since the entire system except for input and output facilities is underground and maintained by hydrostatic pressure, the visual impact above ground would be insignificant. While this project sounds grandiose, it is no more so than Hoover Dam itself. It is a much better use for government money, which is now being wasted on hydrogen and "clean coal" projects.
Early in this century energy technology took a wrong turn when geothermal power was overshadowed by cheap coal and oil. Now the oil is running out and the unintended consequences of coal are killing people and ruining the planet. The problem now is a political one. Energy policy is determined by experts and lobbyists from the fossil fuel industry. We must derail the fossil energy juggernaut before it is too late.
Thomas R. Blakeslee is president of The Clearlight Foundation, a non-profit organization that invests in renewable energy and other socially useful companies and issues cash grants to individuals who are working effectively for change.