It is a form of renewable energy derived from heat deep in the earth’s crust,
in the earths molten interior.
It is the heat energy that is responsible for tectonic plates, volcanoes and
earthquakes. The origin of this heat is from heat generated during the earths
formation and heat generated from the decay of radioactive isotopes.
The temperatures within the earth are extremely high, and can reach as
high as 7000 degrees.
The heat is brought to the near-surface by thermal conduction and by
intrusion into the earth's crust of molten magma originating from great depth.
The hot molten rock heats the surrounding groundwater, which is forced to
the surface in the form of hot steam or water.
When the heat comes close or near to the earths surface it can therefore
be utilized as a source of energy. This is known as GEOTHERMAL
ENERGY! This produces electrictiy.
The regions where the energy can be utilised –
regions where the most heat is produced.
Many areas have
along the circum-
Pacific "Ring of
rift zones and other
hot spots. In these
regions the heat is
rapidly from the
earths interior to the
earths surface so
energy can therefore
be produced, and
Installed capacity MWe 2001
USA 2002 Italy 762
Turkey 20 Japan 549
Mexico 858 China 29
Guatemala 33 Thailand 0.3
El Salvador 161 Guadeloupe 4
Nicaragua 70 Ethiopia 9 1931
Costa Rica 143 Kenya 58
New Zealand 437
These were the first type of
power generation plants
They use steam from the
geothermal reservoir ( in the
earths surface) from wells
and the steam is transferred
through generators and
turbines to produce
An example of a dry steam
generation operation is at
the Geysers in northern
These are the plants that are most
common type of geothermal power
generation plants used today.
They use water at temps more
than 186 degrees, and that is
pumped under high pressure to the
generation equipment at the
When it reaches the surface the
pressure is reduced, allowing some
of the hot water to convert or ‘flash’
This steam is then used to power
the turbine /generator units to
The remaining hot water not
flashed into steam and the water
condensed from the steam is
pumped back into the reservoir.
An example of an area that uses
the flash steam operation is
Calenergy Navy 1 Flash.
Differs from flash and dry
The water or steam from the
geothermal reservoir never
comes in contact with the
turbine or generator units.
The water from the
geothermal reservoir is used
to heat another fluid which is
vaporized and used to turn the
The geothermal water and
the working fluid are confined
in separate circulating systems
and never come in contact
with each other.
These plants can operate at
a lower temp which is an
advantage., and produce no
An example of an area using
a Binary Cycle power
generation system is the
Mammoth Pacific binary
geothermal power plants at
the Casa Diablo geothermal
The operating costs are low.
Earth energy can provide heating in winter, cooling in summer, and year-round hot water for
home use. A single system performs all necessary functions and requires only a flick of a switch
to reverse the unit for a seasonal change .
The systems do not produce the odour that is found in natural gas, oil or propane furnaces.
That makes earth energy systems perfect for highly-insulated buildings or for people who are
allergic or sensitive to noxious gases and poor air quality.
The land area required for geothermal power plants is smaller per megawatt than for almost
every other type of power plant. Geothermal installations don't require damming of rivers or
harvesting of forests -- and there are no mine shafts, tunnels, open pits, waste heaps or oil spills.
Geothermal projects can offer all of the above benefits to help developing countries grow
without pollution. And installations in remote locations can raise the standard of living and quality
of life by bringing electricity to people far from "electrified" population centers.
the processes used to extract energy move at a much higher rate
than the processes that return energy into the geothermal
There are not many places where you can build a geothermal power
station, this is due to the fact that the plants cannot be built in areas
where the temp in the earth is low. Also a large depth is needed to
drill holes into the ground.
Hazardous gases and minerals may come up from underground,
and can be difficult to safely dispose of.
Geothermal energy doesn’t create much employment. This could
affect some people and therefore the standard of living for these could
reduce , and income, and problems would be created with finding
The impact on the environment is considerably lower than using fossil fuels or a
The hydrogen sulphide released could convert to sulphur dioxide that contributes to
acid rain but it is highly unlikely.
Instead it converts into sulphur which falls with precipitation and collects harmless
Geothermal power plants, like wind and solar power plants, do not have to burn fuels
to manufacture steam to turn the turbines. Therefore this helps to conserve
nonrenewable fossil fuels, and by decreasing the use of these fuels, we reduce
emissions that harm our atmosphere. There is no smoky air around geothermal power
plants -- in fact some are built in the middle of farm crops and forests, and share land
with cattle and local wildlife.
Most of it is generated by
hydroelectric stations. Sits on mid Atlantic ridge.
Significant producer of
Geothermal is used in
geothermal energy for some time.
Wairahei. The power station here
has been running since 1958. Has 250 low temp geothermal
and has generated 192mw. fields and 23 high temps.
86% of its domestic usage is
The geothermal energy from geothermal sources.
capacity in New Zealand is over
2000 megawatts and supplies for It currently produces 40ej in this
way and has a capacity of 1000ej.
industrial and domestic demand.
Heating bills are lower for the
There is scope in New Zealand residents , and are lower than
for more geothermal power those in the UK despite the colder
stations as demand increases. climate and higher cost of living.
The smell from the hydrogen
sulphide is a minor inconvenience
to tolerate for the sake of a cheap
There is some potential in the uk, which is distant from plate
Some low flow aquifers are found in the Southampton and
Cleethorpes areas, while better prospects exist in the igneous rocks of
south west England,
These are hot dry rocks which could heat water pumped down to
Improvements in technology are required before the uk would be able
to carry out geothermal energy production, and rival Iceland.