Environmental Engineering Reference
In-Depth Information
6
Geothermal Energy
The U.S. Geological Survey has calculated that the heat energy in the upper 10 kilome-
ters of the Earth's crust in the U.S. is equal to over 600,000 times the country's annual
non-transportation energy consumption. Probably no more than a tiny fraction of this
energy could ever be extracted economically. However, just one hundredth of 1% of the
total is equal to half the country's current non-transportation energy needs for more
than a century, with only a fraction of the pollution from fossil-fueled energy sources.
McLarty et al. (2000)
Geothermal heat is the only renewable energy source created naturally by the Earth
itself.
—Kimberly K. Smith, Carlton College
If we utilize waste biomass, solar (passive and thermal), wind (on shore), photovoltaic,
geothermal, and other renewable resources available to us in the United States, we
would exceed the demand (what we need) by at least five times as much energy as we
need, all from clean, renewable sources.
—Frank R. Spellman
On May 30, 2009, at 5:00 p.m., a worker of Terra-Gen Operating Company LLC was
seriously injured with second- and third-degree burns to his body while at the com-
pany's remote worksite near Inyokem, California, performing his regular assigned
duties as an operation supervisor at the geothermal electric power generation facil-
ity. The worker observed a leak of 150 to 160°F geothermal water coming from a
temporary diesel engine-powered pump and piping system at a collection pond. He
shut off the diesel engine of one of the five temporary pumps at the site, then turned
around to walk away. After rotating his body he fell into a pool of heated water. The
pressurized water from the leak gouged out an approximately 2-foot-deep depression
in the sand and gravelly desert soil. He radioed a coworker and alerted him of the
incident. The company's emergency action plan was implemented. The worker was
airlifted to Fresno Regional Medical Center to receive treatment. An inspection was
initiated by the OSH Fresno District Office.
INTRODUCTION
*
Approximately 4000 miles below the Earth's surface is the core, where temperatures
can reach 9000°F. This heat—geothermal energy (
geo
meaning “earth” and
ther-
mos
meaning “heat”)—flows outward from the core, heating the surrounding area,
which can form underground reservoirs of hot water and steam (
Figure 6.1
). These
*
Adapted from USDOE,
Renewable Energy: An Overview
, U.S. Department of Energy, Washington,
DC, 2001 (http://www.nrel.gov/docs/fy01osti/27955.pdf).
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