Mar 1, 2012
What Makes You Boil?
Geothermal energy developers plan to pump 24 million gallons of water into the side of a dormant volcano in central Oregon this summer to demonstrate technology they hope will give a boost to a green energy sector that has yet to live up to its promise.
They hope the water comes back to the surface fast enough and hot enough to create cheap, clean electricity that isn't dependent on sunny skies or stiff breezes — without shaking the earth and rattling the nerves of nearby residents.
The federal government, Google and other investors are interested enough to bet $43 million on the Oregon project. They are helping AltaRock Energy of Seattle and Davenport Newberry Holdings of Stamford, Conn., demonstrate whether the next level in geothermal power development can work on the flanks of Newberry Volcano, about 20 miles south of Bend, Ore.
The heat in the earth's crust has been used to generate power for more than a century. Engineers gather hot water or steam that bubbles near the surface and use it to spin turbines that create electricity. Most of those close-to-the surface areas have been exploited. The new frontier is places with hot rocks, but no cracks in the rocks or water to deliver the steam.
To tap that heat — and grow geothermal energy from a tiny niche into an important source of green energy — engineers are working on a new technology called Enhanced Geothermal Systems. Wells are drilled deep into the rock and water is pumped in, creating tiny fractures in the rock, a process known as hydroshearing. Cold water is pumped down production wells into the reservoir, and the steam is drawn out.
Hydroshearing is similar to the process known as hydraulic fracturing, used to free natural gas from shale formations. But fracking uses chemical-laden fluids, and creates huge fractures. Pumping fracking wastewater deep underground for disposal is suspected of leading to recent earthquakes in Arkansas and Ohio. Fears persist that cracking rock deep underground through hydroshearing can also lead to damaging quakes.
EGS has other problems. It is hard to create a reservoir big enough to run a commercial power plant. AltaRock hopes to demonstrate a new technology for creating bigger reservoirs that is based on the plastic polymers used to make biodegradable cups. It worked in existing geothermal fields. The Newberry project will show if it works in a brand new EGS field, and in a different kind of geology, volcanic rock.
EGS is attractive because it vastly expands the potential for geothermal power, which, unlike wind and solar, produces power around the clock in any weather. Natural geothermal resources account for about 0.3% of U.S. electricity production, but a 2007 Massachusetts Institute of Technology report projected EGS could bump that to 10% within 50 years, at prices competitive with fossil fuels.