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About the Demonstration: Water Pressure

August 3, 2012

We’re lucky to have a very engaged audience following the progress of the Newberry EGS Demonstration. Having held public Q&As and met people at local fairs and festivals, and with our ongoing social media presence, we get the chance to field all kinds of questions about geothermal energy, the work we’re doing, and what it could mean for the nation’s energy future.

We’ve created an FAQ with the most common questions, but just because a question is infrequent doesn’t make it any less interesting or important. Here’s a question that wasn’t included on our FAQ, but we’d like to inform you about:

What water pressure will you be using during injection?

The role of water pressure in the demonstration is quite simple: injected water lubricates existing dry fractures allowing a small amount of movement on the fractures  Think of the difference between walking on a dry and wet sidewalk.  On the dry sidewalk, it is pretty hard to slip, but once the sidewalk gets wet, the friction between your shoe and the sidewalk is reduced, so that if you aren’t careful your feet will slip out from under you. That is a lot different than blasting the sidewalk with enough water pressure to break the sidewalk apart, which, in this simply analogy, is what hydrofracking in the Oil and Gas industry does.

Once many fracture move and open slightly, the resulting network of fractures will allow the rock to act as a sort of sponge. We’ll be able to put water in, at which point it will heat up, and then we’ll be able to pump it back out, where it can become a source of energy, just like existing geothermal systems.

Our planned pressure range for the stimulation is estimated to be 1850-2650 psi. That may sound powerful compared to, say, the recommended psi for a bike tire, but consider this: oil and gas stimulations often use pressure up to 10,000 psi. Enhanced Geothermal Systems use only a fraction of the pressure found in other approaches. High enough pressures can actually cause the rock to fail and crack – we’re not using anything near that powerful in the work we are doing.

More questions? Send them our way.

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