Geothermal Energy
Hayley Dutka
James Gallagher
Jonathan Koslop
Overview
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Geothermal Electricity
Geothermal Power Plants
Facts
Legal Movement
Advantages vs Disadvantages
Production Enhancement
Coproduction
Geothermal Electricty
• Geothermal energy is currently used in
24 countries, with the United States
producing the most
• World production has 10,715 MW of
geothermal power capacity online and
produced 67,246 GW h
(gigawatts/hour) in 2010. This is a 20%
increase from 2005
• The International Geothermal
Association (IGA) predicts this number
will grow to 18,500 MW capacity by
2015
Dry Steam Power Plants
• Dry steam plants are the simpliest and oldest
• Use geothermal steam of 150°C or greater to turn turbines
Flash Steam Power Plants
• Flash steam plants pull deep, high pressure hot water into lower-pressure tanks
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and use the resulting flashed steam to drive turbines.
Require fluid temperatures of at least 180°C, usually more.
Most common type of plant in operation today
Binary Cycle Power Plants
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Recently developed
Can accept fluid temeratures as low as 57°C
The moderately hot geothermal water is passed by a secondary fluid with a much
lower boiling point than water. This causes the secondary fluid to flash vaporize,
which then drives the turbines.
Hot Dry Rock Geothermal Heating
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In order to generate electricity you need the heat from in the earth which must be
carried to the surface by fluid circulation.
In some situations fluids are unavailable so it is possible to inject water or liquefied
carbon dioxide down a borehole to extract the heat
Facts about Geothermal Energy
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There is an enormous amount of thermal energy deep within the earth, that is
replenished at a very high rate. This amount is conservatively estimated to be
higher than all the fossil fuels and uranium combined
Geothermal electricity only gives off an 1/8th (12.5%) of the emissions that coal
does. Also other types of power plants are usually equipped with emission-control
systems to reduce exhaust. Geothermal plants could theoretically inject their gas
emissions back into the earth, as a form of carbon capture and storage
Geothermal plants use 404 square meters per GWh versus 3,632 and 1,335 square
meters for coal facilities and wind farms respectively
Only uses 20 liters of freshwater per MWh verses over 1000 liters per MWh for
nuclear, coal, or oil.
Geothermal energy is not susceptible to price fluctuation like crude oil
The US government has offered tax credits for individuals who use the technology
in their homes. So basically you could have one of the highest efficiency heating
and cooling systems in your home for a discount.
Geothermal energy is always available, 365 days a year.
Laws, Advantages, and
Disadvantages
Most Recent Legal Movement
• Energy Independence and Security Act of 2007,
which includes the “Advanced Geothermal
Research and Development Act of 2007” is the
most recent direction and authorization provided
by the House and Senate.
• “In General- The Secretary shall support programs of research,
development, demonstration, and commercial application to
expand the use of geothermal energy production from
hydrothermal systems, including the programs described in
subsection (b).”
Advantages of Geothermal Energy
• 1. Environmentally Friendly – There are some polluting
aspects associated with geothermal energy, but not near
the amount of polluting aspects associated with
conventional fuel sources. (coal, fossil fuels). The power
stations do not take up much room, so there is not much
impact on the environment
• 2. Renewable - reservoirs come from natural resources
and are naturally replenished. Geothermal energy is a
resource that can sustain its own consumption rate – Unlike
conventional energy sources such as coal and fossil fuels.
Geothermal energy generally involves low running costs
since it saves 80% costs over fossil fuels and no fuel is used
to generate the power
Advantages Continued…
• 3. Massive Potential - Worldwide energy consumption –
about 15 terawatts (TW) – is not anywhere near the
amount of energy stored in earth. However, most
geothermal reservoirs are not profitable and we can only
utilize a small portion of the total potential. Realistic
estimates for the potential of geothermal power plants vary
between 0.035 to 2 TW.
• 4. Stable - Geothermal energy is a reliable source of energy.
We can predict the power output of a geothermal power
plant with remarkable accuracy. This is not the case with
solar and wind (where weather plays a huge part in power
production). Geothermal power plants are therefore
excellent for meeting the base load energy demand.
Advantages Continued…
• 5. Great for Heating and Cooling - We need water temperatures of
more than 150°C (about 300°F) or greater in order to effectively
turn turbines and generate electricity with geothermal energy. The
earth is generally more resistant to seasonal temperature changes
than air. Consequently, the ground only a couple of meters below
the surface can act as a heat sink/source with a geothermal heat
pump.
• 6. Prevalence and Economy - There has been a tremendous
growth in the number of homeowners that utilize geothermal
heating/cooling in the last couple of years. Since ancient times,
people having been using this source of energy for taking bath,
heating homes, preparing food and today this is also used for direct
heating of homes and offices. Geothermal energy on the other
hand has created many jobs for the local people.
Disadvantages of Geothermal Energy
• 1. Environmental Issues - There is an abundance of greenhouse
gases below the surface of the earth, some of which mitigates
towards the surface and into the atmosphere. These emissions tend
to be higher near geothermal power plants. Geothermal power
plants are associated with sulfur dioxide and silica emissions, and
the reservoirs can contain traces of toxic heavy metals including
mercury, arsenic and boron.
• 2. Surface Instability (Earthquakes) - Construction of geothermal
power plants can affect the stability of land. In fact, geothermal
power plants have lead to subsidence (motion of the earth’s
surface) in both Germany and New Zealand. Earthquakes can be
triggered due to hydraulic fracturing, which is an intrinsic part of
developing enhanced geothermal system (EGS) power plants.
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https://www.google.com/search?q=newcastle+australia+earthquake&source=lnms&tbm=isch&sa=X&ei=DKyLUoy
ZNszh4APbxIGwDg&sqi=2&ved=0CAcQ_AUoAQ&biw=1920&bih=1084#q=newcastle+australia+earthquake+1989&
tbm=isch
Disadvantages Continued…
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3. Expensive - Commercial geothermal power projects are expensive. The
exploration and drilling of new reservoirs come with a steep price tag (typically
half the costs). Total costs usually end up somewhere between $2 – 7 million for a
geothermal power plant with a capacity of 1 megawatt (MW). The upfront costs of
geothermal heating and cooling systems are also steep. On the other hand, these
systems are likely to save you money years down the line, and should therefore be
regarded as long-term investments. Ground source heat pumps typically costs
$3,000 – $10,000 and have a payback time of 10 – 20 years.
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4. Location Specific - The big problem is that there are not many places where you
can build a geothermal power station. You need hot rocks of a suitable type, at a
depth where we can drill down to them. The type of rock above is also important,
it must be of a type that we can easily drill through. Good geothermal reservoirs
are hard to come by. Some countries have been blessed with great resources –
Iceland and Philippines meets nearly one third of their electricity demand with
geothermal energy. If geothermal energy is transported long distances by the
means of hot water (not electricity), significant energy losses has to be taken into
account.
Disadvantages Continued…
• 5. Sustainability Issues- Rainwater seeps through the
earth’s surface and into the geothermal reservoirs over
thousands of years. Studies show that the reservoirs
can be depleted if the fluid is removed faster than
replaced. Efforts can be made to inject fluid back into
the geothermal reservoir after the thermal energy has
been utilized (the turbine has generated electricity).
Geothermal power is sustainable if reservoirs are
properly managed. This is not an issue for residential
geothermal heating and cooling, where geothermal
energy is being used differently than in geothermal
power plants.
Can production be enhanced in those
areas in which it is already developed?
YES!
EGS
• An approach to capturing the heat in dry
areas under the earths surface.
EGS
Co-Production
• Oil and Gas companies.
• Allows for geothermal to be produced in
areas with little activity.
Co-Production
Shale
• Since shale and the drilling of it are relatively
new this is good for geothermal.
Shale
Questions/Comments?
• http://www.youtube.com/watch?v=O6r_3AgI
49Y&feature=player_embedded
Works Cited
• http://energyinformative.org/geothermalenergy-pros-and-cons/
• http://geoenergy.org/KeyGeothermalLaws.aspx
• http://www.geothermal-energy.org/