A new technology seeks to use the natural heat in the Earth’s crust to create a clean, quiet and inexhaustible source of energy which could meet the world’s annual needs many times over.
When tremors started cracking walls and bathroom tiles in Basel, Switzwerland, engineers knew they had a problem.
The tremor was no ordinary act of nature: it had been accidentally triggered by engineers drilling deep into the Earth’s crust to tap its inner heat and thus break new ground in the world’s search for new sources of energy.
Geopower Basel, the power company in charge of the project, is trying to generate power commercially by boiling water on the rocks five kilometers underground.
On paper, the project straightforward: Drill down, shoot cold water into the shaft and bring it up, again through a steam turbine. The resulting superheated water is capable of generating enough power to meet the electricity needs of 10,000 modern house holds.
Scientists say this geothermal energy – clean, quiet and virtually inexhaustible – could fill the world’s annual needs 250,000 times over with nearly zero impact on the climate of the environment.
Hot Dry Rocks
A study released this year by US based Massachusetts Institute of Technology said if 40% of the heat under the US alone could be tapped it would meet demand 56,000 times over.
The resource base for geothermal is enormous. Hot dry rock technology also called ‘enhanced geothermal systems’ drills down to where the layers of granite are close to 200 degrees Celsius. But the technology is meant to stay well away from the 99% of the Earth’s interior.
After boring the first shaft, water is pumped down the injection well. As it seeps through the layers of rock below the water heats up.
But in Basel, that’s where the water remains for the time being; it caused the rock layers to slip, resulting in tremors that spooked the town people, who called for the project to be shut down.
The next step would have been to be drill two wells that suck the pressurized, superheated water out of the cracks and up to the surface, to create steam to drive a turbine and generating electricity.
The water, having cooled to around 170 degrees Celsius would heat hospitals, public buildings and homes before being pumped back into the ground for another waste-free, gas free cycle
However, there are drawbacks – not just earthquakes, but cost. A so-called hot rock well about five kilometers deep would cost up to $8 million (over Rs 32 crore approx) – much higher than the average cost of drilling an oil well. Also, rocks by drilling would lose their heat after a few decades and new wells would have to be drilled elsewhere.
Experts say hot rock geothermal energy can operate throughout the day and doesn’t depend on sun or wind. However, it’s just getting started and is decades away from serious rivalry with existing energy sources.
Promoters of the technology say that while costly, it’s cheaper to run once it’s in place. The study said it could provide electricity at competitive prices. Price comparisons indicate it could be cheaper than other forms of renewable energy, including biomass and solar power. The outlook is very good that we can do it, says executive director of the Geothermal Energy Association.