Environmental Engineering Reference
In-Depth Information
Table
Surface area requirements and subsurface
fractured rock volume for EGS plans of a given electrical output
.
Electric output
(MWe)
Surface area
(square kilometers)
Subsurface volume
(cubic kilometers)
.
.
.
.
.
.
.
.
output and the very large deep subsurface volume of the
fractured rock region required to produce the indicated
electrical energy. They assume a
-
ciency of heat to electricity, and a re-drilling and creation
of a new subsurface reservoir in a new area after
% conversion effi-
ve years
of operation of a given well system to make up for the
cooling of the rock.
There are environmental concerns about EGS, particu-
larly about microseisms or tiny earthquakes. A munitions
plant near Denver, Colorado, began to dispose of its
chemically contaminated water by injecting it deep under-
ground. This seemed like a good idea at the time; careful
environmental studies were done to see that there would
be no contamination of the water supply of Denver or
anywhere else in the region, and even the protestors
were satis
ed about that issue. What no one had thought
of was the possibility of tiny earthquakes arising from
the lubrication of the natural cracks in the rocks deep
underground. After pumping had gone on for a while
tiny tremors began to be felt in the region and these
continued until, as an experiment, pumping was stopped.
With the cessation of pumping came a cessation of
