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Geothermal energy in San Bernardino
The City of San
Bernardino, California, uses geothermal energy directly in a
district-heating program. The city of San Bernardino is located
near several earthquake fault zones, including the San Jacinto ,
Loma Linda, and San Andreas faults. The consequences of being close
to these faults is that, since the turn of the century, residents
of San Bernardino have enjoyed natural heat in the form of steam
baths and hot springs. Many wells in the valley are between 120º
and 140º F. The heating district lies in the southwest portion of
the city and currently serves more than 35 public and private
buildings. Similarly, geothermal water warms greenhouses in Idaho ,
nurtures fish in Utah , and provides hot baths at resorts in
Virginia. Geothermal Energy has been around for as long as
the Earth has existed. "Geo" means earth, and "thermal" means heat.
So, geothermal means earth-heat.
Have you ever cut a
boiled egg in half? The egg is similar to how the earth looks like
inside. The yellow yolk of the egg is like the core of the earth.
The white part is the mantle of the earth. And the thin shell of
the egg, that would have surrounded the boiled egg if you didn't
peel it off, is like the earth's crust.
Below the crust of the earth,
the top layer of the mantle is a hot liquid rock called magma. The
crust of the earth floats on this liquid magma mantle. When magma
breaks through the surface of the earth in a volcano, it is called
lava.
For every 100 meters you go
below ground, the temperature of the rock increases about 3 degrees
Celsius. Or for every 328 feet below ground, the temperature
increases 5.4 degrees Fahrenheit. So, if you went about 10,000 feet
below ground, the temperature of the rock would be hot enough to
boil water.
Geothermal hotspots in California are displayed in
red.
Advantages
Geothermal energy offers a
number of advantages over traditional fossil fuel based sources.
From an environmental standpoint, the energy harnessed is clean and
safe for the surrounding environment. It is also sustainable because the
hot water used in the geothermal process can be re-injected into
the ground to produce more steam. In addition, geothermal power
plants are unaffected by changing weather conditions. Geothermal power works
continually, day and night, providing baseload power. From an
economic view, geothermal energy is extremely price competitive in
some areas and reduces reliance on fossil fuels and their inherent
price unpredictability. Given enough excess capacity,
geothermal energy can also be sold to outside sources such as
neighboring countries or private businesses that require energy. It
also offers a degree of scalability: a large geothermal plant can
power entire cities while smaller power plants can supply more
remote sites such as rural villages.
Disadvantages
There are several
environmental concerns behind geothermal energy. Construction of
the power plants can adversely affect land stability in the
surrounding region. This is mainly a concern with Enhanced
Geothermal Systems, as they involve drilling very deep and
injecting water into hot dry rock where no water was before.
Dry steam and flash steam power plants also emit low levels of
carbon dioxide, nitric oxide, and sulfur, although at roughly 5% of
the levels emitted by fossil fuel power plants. Geothermal plants
can be built with emissions-controlling systems that can inject
these gases back into the earth, thereby reducing carbon emissions
to less than 0.1% of those from fossil fuel power
plants.
Although geothermal sites are
capable of providing heat for many decades, eventually specific
locations may cool down. It is likely that in these locations, the
system was designed too large for the site, since there is only so
much energy that can be stored and replenished in a given volume of
earth. Some interpret this as meaning a specific geothermal
location can undergo depletion, and question whether geothermal
energy is truly renewable, but if left alone, these places will
recover some of their lost heat, as the mantle has vast heat
reserves. The government of Iceland states: "It should be
stressed that the geothermal resource is not strictly renewable in
the same sense as the hydro resource." It estimates that
Iceland's geothermal energy could provide 1700 MW for over 100
years, compared to the current production of 140 MW.
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