Geothermal energy
1-Introduction:
. Geothermal energy is the earth’s natural heat available inside the earth. This thermal energy contained in the rock and fluid that filled up fractures and pores in the earth’s crust can profitably be used for various purposes. Heat from the Earth, or geothermal — Geo (Earth) + thermal (heat) — energy can be and is accessed by drilling water or steam wells in a process similar to drilling for oil. Geothermal energy is an enormous, underused heat and power resource that is clean (emits little or no greenhouse gases), reliable (average system availability of 95%), and homegrown (making us less dependent on foreign oil). In fig (1).
. Geothermal resources range from shallow ground to hot water and rock several miles below the Earth's surface, and even farther down to the extremely hot molten rock called magma .
. Electricity is produced by geothermal in 24 countries , five of which obtain 15-22% of their national electricity production fron geothermal energy .
2- Definition:
.
Geothermal energy is defined as heat from the Earth. It is a clean, renewable
resource that provides energy in the U.S. and around the world in a variety of
applications and resources.
. Geothermal plants are relatively capital-intensive, with low variable
costs and no fuel costs.
3- Working principle:
. The heat inside the Earth heats up a
boiler with water inside .This makes the water`s temperature rise and transform
it into steam .The steam moves a turbine connected to a generator that produces
electricity. Then .the steam goes to a condenser where it becomes water which
returns to boiler again. Show in fig (2).
. there are 3 types of power plant .
ü Dry steam power plant.
ü Binary cycle power plant.
ü Flash steam power plant.
4- Advantages:
ü It is a renewable source of energy.
ü By far, it is non-polluting and environment friendly.
ü There is no wastage or generation of by-products.
ü Geothermal energy can be used directly. In ancient times, people
used this source of energy for heating homes, cooking, etc.
ü Great way to save energy and money.
ü Independent of weather.
5- Disadvantages:
ü Only few sites have the potential of Geothermal Energy.
ü Most of the sites, where geothermal energy is produced, are far
from markets or cities, where it needs to be consumed.
ü Total generation potential of this source is too small.
ü There is always a danger of eruption of volcano.
ü High installation cost.
ü Can run out of steam.
ü May release harmful gases.
ü Transportation.
6- Applications:
.Direct use and indirect use .
Direct:
ü Hot springs, used as spas.
ü Heating water at fish farms.
ü Provide heat for buildings.
ü Raising plants in greenhouses , drying crops.
ü Provides heat to industrial processes.
Indirect.
ü
Electricity
generation.
.With over 8000 MW of installed
capacity, geothermal electric power generation is a well-proven technology that
has been especially successful in countries and islands that have a high
reliance on imported fossil fuels (World Bank Group, 2004).
7-Conclusion:
ü Geothermal heating system can replace fossil fuel hating system in
a particular area.
ü Annual costs for common heating purpose can be reduced by more than 60%
ü Continued energy shortages have created added interest in
geothermal energy for power generation.
ü Potential exists to provide all energy requirements in the U.S.
ü Geothermal energy appears to be a partial solution to our energy
needs.
8- References:
- www.slideshare.net.
-http://greenlivingideas.com/2007/10/22/the-uses-of-geothermal-energy/
- srren.ipcc-wg3.de/report/IPCC_SRREN_
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