Econintersect: The Newbury volcano in Oregon is the region's largest shield volcano which most recently erupted over an active period from about 480 AD to about 700 AD. The shield dome is of the order of 20 miles wide (maximum east to west) and 45 miles long (north to south) located just south of Bend, OR. The seven mile diameter caldera is about 30 miles south-southeast of Bend. (See map below.)
A geothermal development project is underway to build an electricity generating facility using the 6000F (3000C) thermal energy available near the surface from less than a mile to more than two miles down.
Map from Wikopedia.
The project is called the Newbury EGS demonstration, funded by the U.S. Department of Energy (DOE Geothermal Technologies Program) and two private companies, Altarock Energy and Davenport Newbury Holdings. The thermal drilling areas are four to five miles from the center of the caldera and one to two miles outside the rim.
The process of creating subterranean aqueous thermal reservoirs involves a process of hydroshearing, a cousin to the hydrofracking process which has come under criticism in the process of extracting natural gas from shale formations. The main differences between the fracturing process for natural gas extraction and that for thermal energy extraction include:
- Much less freshwater required for geothermal;
- Fewer surface sites for geothermal;
- Geothermal extraction has a closed recycling material system while natural gas production is continuously removing material from fracking fluids;
- Geothermal depends on cold water thermal shock for producing slippage in existing fractures in subterrainian rock while shale fracking uses added slurries to enhance shale fracturing;
- Geothermal processes involve fluid pressures much lower (25%-30%) compared to hydrofracking.
While there seem to be fewer potential problems with geothermal reservoir creation than with fracking, there are potential environmental impacts, which include:
- Subterranean fluids contain gases including CO2, hydrogen sulfide, methane and ammonia;
- Subterranean fluids may contain trace amounts of mercury, arsenic, boron, antimony and other compounds and minerals;
- Land subsistence has been observed;
- Hydraulic fracturing has produced seismic events.
The headline for this article is actually misleading. The United States is already the largest geothermal power producer in the world, more than 60% ahead of number two Philippines and almost 2.6x number three Indonesia. However the contribution to total power for the country was less than 1 % in 2010. For Iceland, Philippines and El Salvador geothermal generation provides from 25% to 30% of all power.
Table from Wikipedia.
- Volcano power plan gets U.S. go-ahead (Brian Dodson, Gizmag, 31 October 2012)
- Altarock Energy Inc (Company Website)
- Newbury Geothermal (Davenport Newbury Holdings LLC (Company website)
- Geothermal electricity (Wikipedia)
- Hydraulic Fracturing (Wikipedia)