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GEOTHERMAL ENERGY
Veronica Boyer - Geology 100 Web - Spring 2012
GEOTHERMAL ENERGY
Geothermal Greek roots: geo (earth) and therme (heat). Meaning “Earth's heat”.
Is thermal energy generated and stored in the earth.
Thermal energy is the energy that
determines the temperature of matter.
Originates from from the original
formation of the planet 20% and from
radioactive decay of minerals. 80%.
Geothermal gradient is the difference
in temperature between the core of
the planet and its surface, drives a
continuous conduction of thermal
energy in the form of heat from the
core to the surface.
Inner Earth´s heat - Result of radiactive decompose of elements in rocks, which continuously
regenerates this heat, for this reason, geothermal energy is a renewable energy resource.
Geothermal Energy has huge potential because is
50,000 times bigger from all energy that can be
gained from oil and coal accross the world.
Geothermal resources are located from shallow
surface to couple of kms deep reservoirs of hot
water springs, wells and geysers, which could be
brought to surface and there exploited.
Water or steam - Medium that is
transfering heat from inner core to
surface, since heat is always
transferring from hotter to colder
parts, this heat is the major mover of
tectonic plates.
Temperature rises 50-87°F every one
mile deeper from the earth´s crust.
The mantle composed of partly melted
rocks has a temperature of
1200-2800°F and Earth´s core of
7200-12600°F.
USES:
- For millenniums for recreational-sanative bathing.
- Now, for generating electricity and as the central heating of households and buildings.
ELECTRICAL ENERGY
PRODUCTION
- Hot water and steam from earth is
used for initiation of generators
- 1911 in Larandello - First geothermal
power station with power of 250Kw
- Well developed geothermal systems
are located in geologically active areas
with continuous, concentrated heat
flow to the suface.
- Geothermal facilities must use of a
closed loop system at all times or the
re-injection of water back into the
system for constant steam generation.
DISADVANTAGES:
- Not many places are suitable for exploiting.
- Best areas are on the edges of tectonic plates located on the ring of fire.
Ring of fire (area with high volcanic and tectonic activity)
TYPES OF GEOTHERMAL POWER STATION
- Dry Steam - Extremely hot steam, above 445°F runs generatos
Ex. - Larandello´s first station &
Geysers in California since 1960
- Flash Steam - Hot water from reservoirs under great
preassure avobe 360°F
Water transformed onto steam decreasing
preassure
Steam directed to start turbines. Water
returns to reservoir.
Most modern power stations use this principle.
- Binary Cycle - Hot water used to heat a liquid with low
boiling temperature
Liquid is exhausted on temperature of the
hot water
Starts generator turbines, water returns to
reservoir - Min water loss
Newly stations will use this principle.
- Fish breeding
OTHER USES OF GEOTHERMAL
- Heating Buildings - The largest system
is located on Iceland.
- Heat pumps - For circulation of
geothermal liquid for heating, cooling,
cooking and water heat.
- Agriculture For increase of the crop at greenhouses
- Balneology Hot springs bathing for healing and recreation
ADVANTAGES
- In this processes, there is no
combustion of fossil fuels
- No harmful emissions of gases to
the atmosphere
- Only water steam gets released
- Water is returned to reservoirs
- Could soften pressure on fossil fuels
helping earth recover from dangerous
greenhouse gases.
EARTH ENERGY
Type of Geothermal Energy “Heat pumps”
- Used commercially
- Extracted through heat pumps
- Heat contained in shallow ground (Upper 10’ of the
earth) is used to directly heat or cool houses since the
temperature inside the ground tends to stay at the
yearly average.
- On winter ground is warmer than the air. On
summer, ground is cooler than the air.
- This system (Ground heat exchanger) acts as an air
conditioner.
- The shallow ground mantains a nearly constrant
temperature between 50° - 60° F
- Consists of a heat exchanger (loop of pipes) buried in
the shallow ground near the building. A fluid (water or
mixture of water-antifreeze) circulates through the
pipes to absorb or relinquish heat within the ground.
EARTH ENERGY
Advantages:
- Could be utilized
anywhere
- Could also be used to
heat water
- Reduces the reliance on
other resources.
- Significant environmental
benefits and reduced
energy costs
- No active technology is
more efficient than the
“Geothermal heat pump”
WHY WE DON’T USE THIS SYSTEMS MORE
- Fields of sufficient quality to produce economic electricity are rare.
- Many fields are located in protected wilderness areas that enviromentalists preserve.
- There is a need to harvest geothermal power through non traditional means, such as
deep crustal drilling or the acquisition of heat from magma to preserve those scarce
fields.
- There is a an enviromental concern - Some applications produce carbon dioxide and
hydrogen sulfide emissions and dispose of toxic waste and dissolved solids.
- There is a very large geothermal resource in the world, much of which can not yet be
economically used.
- Our current technology is not sufficient or economical enough to warrant its
widespread use.
- Funding for energy extraction that involves the penetration of magma is not available
because we don’t kow how to prevent a high-temperature, high pressure blowout.
- Heat pumps can help reduce bill by $1 per day, not economically viable. Payback period
longer than 5 years.
- Earth energy is not intense enough to produce power for the electrical distribution
grid, it only reduces the drw from the grid.
RENEWABLE ENERGY
PRODUCTION BY STATE
REFERENCES
1. http://energy.gov/science-innovation/energy-sources/renewable-energy/geothermal
2. http://geothermal.marin.org/index.html
3. http://www.geo-energy.org/
4. http://www.renewableenergyworld.com/rea/tech/geothermal-energy
5. http://www.altenergy.org/renewables/geothermal.html
6. http://www.our-energy.com/geothermal_energy.html
7. http://energy.gov/maps/renewable-energy-production-state
8. http://greenlaurier.ca/wp-content/uploads/2010/10/GEOTHERMAL-system-in-house.jpg
THANKS!