MORE GEOTHERMAL FROM LASER DRILLING

Laser drills could relight geothermal energy dreams

Jeff Hecht, 13 December 2012 (New Scientist)

“From fossil fuels to geothermal heat, accessing the planet's energy riches usually involves boring deep into the Earth with giant metal drills. But could lasers do the same job?...Foro Energy, a start-up company in Littleton, Colorado, has developed what it claims is an inexpensive system of high-powered lasers that can rip through rock, potentially revolutionising drilling and hastening the adoption of greener forms of power…

“…[A] test system [funded by the US Department of Energy's research arm, ARPA-E, has] sent a beam from a 20-kilowatt commercial laser through 1.5 kilometres of optical fibre…Borehole drilling trials are planned for next year.”

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“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. It is these harder 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 mechanical drill can scrape away quickly and with little wear. This approach could increase drilling rates, a major component in well cost, by up to a factor of 10, says ARPA-E.

“…[A] flashy prototype is far from proof that the rig will hold up in the brutal environment found in the bottom of a borehole…[but] the cost of drilling has been a roadblock to expanding the adoption of geothermal energy. If Foro can prove its technology is ready for the grunt work of punching hundreds of holes through the hard igneous rocks, it would change the mathematics of low-carbon energy…”

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