By Liat Clark, Wired UK

With reports only recently confirming that fracking is not, as long as its properly regulated, the earthquake-generating terror we thought it was, a U.S. geothermal company has decided it's a great idea to extract clean energy from a dormant volcano by hydrofracking its hot underbelly to generate steam.

[partner id="wireduk" align="right"]AltaRock Energy and Davenport Newberry, the companies behind the $43 million plan, have been granted a permit to hydrofrack the hot rocks flanking the Newberry volcano in Oregon, where Davenport Newberry has secured federal leases on 62 square miles of land. This will involve injecting water into a series of cracks in the rocks at a high enough pressure that it reaches three kilometres beneath the surface, fracturing connected veins of rock to access the heat beneath and creating a series of connected geothermal reservoirs in the process. Water will be introduced to these reservoirs, where heat from the rocks will turn it to steam, which then turns turbines at surface-level to generate electricity.

Susan Petty, president and founder of AltaRock Energy, said in a company blog post that "creating multiple reservoirs from a single injection multiplies the amount of energy that can be extracted from each production well," and will "extend the life of the well and increase the energy recovery from each well, significantly improving the economics of enhanced geothermal system power generation."

Fracking is a method typically used to extract fossil fuels, and one that has caused controversy in recent years because of its potential to trigger (albeit mild) earthquakes. According to a recent survey by the Royal Society and the Royal Academy of Engineering, however, earthquakes are unlikely if companies employ "best practice" and enforce strict regulatory procedures. With any risk factor at all, however, it seems odd that a volcano would be a first choice to set up shop. Especially when that volcano hasn't erupted for 1,400 years and the U.S. Geological Survey says it "is certain to erupt again".

If it's successful, though, the system will be a huge step up from the standard geothermal energy extraction practice of using steam from convective hot water wells that occur naturally underground. Rather than looking for that water, this enhanced geothermal system (EGS) goes straight to the heat's source – the hot rocks. According to a 2006 report by MIT into the benefits of EGS, a projected investment of $1 billion in the U.S. over a 15-year period could deliver more than 100,000 electric megawatts (MWe) of new capacity by 2050. As a comparison, France's largest nuclear reactor produces 1,600 MWe.

Although messing with a geological structure where molten lava bubbles beneath the surface at temperatures of nearly 2,400 degrees Fahrenheit might not sound like the most sensible idea, the move could pave the way for a new kind of cost-effective geothermal energy extraction. It's also been deemed safe by the U.S. Bureau of Land Management, which granted the permit. According to the Bureau's independent studies the project presents no risk of earthquake or water contamination.

The reservoirs are due to be set up this autumn, after which production wells will be drilled to connect the rock fractures. Testing will then be carried out to investigate how good a heat exchanger the spot will be, and an installed advanced microseismic array will provide seismologists with data to verify safety. This phase should be completed by 2014, by which time the team at AltaRock hope the efficacy and cost-efficiency of the method will have been proven.

According to a release from AltaRock, the purpose of the new technology is "to lower the cost of EGS, and thus allow economic extraction of heat from the earth in locations where high temperatures can be reached by conventional drilling techniques but there is no natural circulating geothermal system".

Source: Wired.co.uk