Geothermal Energy
Published on Jan 10, 2016
Abstract
When English inventor Richard Trevithick introduced the steam locomotive on 21 February
1804 in Wales, it achieved a speed of 8 km/h (5 mph). In 1815, Englishman George
Stephenson built the world's first workable steam locomotive. In 1825, he introduced the first
passenger train, which steamed along at 25 km/h (16 mph). Today, trains can fly down the
tracks at 500 km/h (311 mph). And fly they do, not touching the tracks.
There is no defined speed at which you can call a train a high speed train but trains running at
and above150 km/h are called High Speed Trains.
Introduction
Historically , the first application of geothermal energy were for space heating , cooking and
medical purposes . The earliest record of space heating dates back to 1300 in Iceland .In the
early 1800s , geothermal energy was used on what was then a large scale by the conte
Franceso de Laderel to recover boric acid . The first mechanical conversion was in 1897
when the steam of the field at Larderallo, Italy , was used to heat a boiler producing steam
which drove a small steam engine . The first attempt to produce electricity also took place at
Larderello in 1904 with an electricity generator that powered four light bulbs. This was
followed in 1912 by a condensating turbine ; and by 1914, 8.5 MW of electricity was being
produced.
Geothermal energy is also the one of the renewable energy sources, which are defined as
those resource that draw on the natural energy floors of the earth (another term THE
ALTERNATIVE ENERGY SOURCES is also common in use). Renewable energy sources
are so named because they recur , are seemingly inexhaustible, and are free for the taking .
geothermal energy as practically no intermittency, has the highest energy density,& is
economically not far removed from the conventional technologies .geothermal energy
classified as renewable because the earth’s interior is and will continue in the process of
cooling for indefinite future.
Thus there is a vast scope to use geothermal energy for low temperature applications . There
is an ample scope to develop geothermal power in India, but still development in geothermal
field is in initial stage . There are about 340 known thermal areas in India , each represented
by hot/warm spring . About 113 spring area, discovered so far where geothermal power is
available . 46 of these systems are of high temperature type , which could be generate 1838
MW for a period of 30 years .
How Does Geothermal Energy Work
The heat from the earth's core continuously flows outward. It transfers (conducts) to the
surrounding layer of rock, the mantle. When temperatures and pressures become high
enough, some mantle rock melts, becoming magma. Then, because it is lighter (less dense)
than the surrounding rock, the magma rises (convects), moving slowly up toward the earth's
crust, carrying the heat from below.
Sometimes the hot magma reaches all the way to the surface, where we know it as lava. But
most often the magma remains below the earth's crust, heating nearby rock and water
(rainwater that has seeped deep into the earth) - sometimes as hot as 370 degrees C. Some of
this hot geothermal water travels back up through faults and cracks and reaches the earth's
surface as hot springs or geysers, but most of it stays deep underground, trapped in cracks and
porous rock. This natural collection of hot water is called a geothermal reservoir.
Liquid Dominated Geothermal Power Plant
Flash steam plants - take high-pressure hot water from deep inside the earth and convert it to
steam to drive the generator turbines. When the steam cools, it condenses to water and is
injected back into the ground to be used over and over again. Most geothermal power plants
are flash plants. This type of plant injects water and condensate into the geothermal reservoir
through the injection well and forces water at a high temperature (360°F) up through the
production well. From the production well it is pumped through a series of pressure vessels
which are at a lower internal pressure than the hot geothermal fluid, causing it to flash off
into low, medium and high pressure steam. The steam then passes through the steam turbine
condensing and being cooled as in a dry steam plant, returning to the geothermal reservoir
along with the non-condensable gasses through the injection well.
Hot Dry Rock Resources
The known temperature of HDR Very between 150 to 290 degree of temperature . This
energy , called petro thermal energy , represents by far the largest resources of geothermal
energy of any type, as it accounts for large % of geothermal resources . Much of the HDR
occurs at moderate depths , but it is largely impermeable a stated above in order to extract
thermal energy out of it , water will have to be pumped into it and back out to surface . It is
necessary for the heat transport mechanism that a way be found to render the impermeable
rock into a permeable structure with a large heat transfer surface . It is necessary for heat rock
into a permeable structure with a larger heat transfer surface . A larger surface is particularly
necessary because of low thermal conductivity of the rock and then fracturing by 1) high
pressure water or 2) nuclear explosives . Efforts in this direction are in progress.
Conclusion
Hot, dry rock (HDR) is widespread and offers new resources in areas where geyser activity is
un known .Direct low-temperature heat transfer for home systems is practical as long as low
maintenance is designed into the system .Geothermal energy is limited in extent as extracting
the heat usually exceeds the replenishment rate. Sources of high temperature water or steam
are limited and the cost of extraction, maintenance, and operation will remain high in
comparison with other sources of energy.