By Charles Walford
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It has long been thought that tapping the planet's nearly limitless amount of geothermal power would greatly relieve the burden on rapidly depleting fossil fuel sources.
But harnessing such a renewable energy source is currently a slow and expensive progress.
However, now there may be a revolutionary solution to the problems of cumbersome and costly giant drilling equipment - lasers.
While geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations, the capital costs are very high.
Heat is on: US company Foro says it has tested a laser drill that could make harnessing geothermal energy far easier
Steaming ahead: The Nesjavellir Geothermal Power Station in Iceland
Drilling accounts for over half the costs, and exploration of resources deep in the Earth entails significant risks.
But now a US company has offered its alternative solution, the New Scientist reports.
Foro Energy, a start-up company in Littleton, Colorado, has developed what it claims is an inexpensive system of high-powered lasers that can cut through rock.
Foro announced last month that a test system had sent a beam from a 20-kilowatt commercial laser through 1.5km of optical fibre.
Development has been funded by the US Department of Energy's research arm, ARPA-E.
Borehole drilling trials are planned for next year.
Mechanical drills can easily grind through soft rocks like sandstone to tap petroleum reserves, but they wear out quickly in hard crystalline rocks such as granite and basalt, which are found near volcanoes.
Thus it is these rocks that often hide the best sources of geothermal energy.
Foro's intense laser beam heats hard rock surfaces so fast that thermal shock fractures the upper few millimetres, leaving a crumbled layer that a normal mechanical drill can scrape away.
Power source: How geothermal energy can be harnessed
Global geothermal electric capacity: Upper red line is installed capacity; lower green line is realised production
This approach could increase drilling rates, a major component in well cost, by up to a factor of 10, says ARPA-E.
However, the success of the prototype will not be guaranteed to be replicated hundreds of metres underground.
The bottom of a borehole, which is filled with rock chips and churning water that lubricates the drill bit.
But for the laser system to work, the optics must deliver the beam directly to the rock, Jared Potter of Potter Drilling in Redwood City, California, who is developing a drilling process that shatters rock with extremely hot water, told the New Scientist.
If the beam hits fluid, it will heat the liquid instead of the rock face.
Foro 'has a long way to go to have a tool they can deploy in a geothermal or oil well, he adds.
But it is the huge cost of drilling that has hindered the adoption of geothermal energy as a legitimate power source.
If Foro can make it work, it would be a major breakthrought for the way we power our world.
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