Geothermal energy is energy obtained by tapping the heat of the earth itself, usually from kilometers deep into the Earth's crust. It is expensive to build a power station but operating costs are low resulting in low energy costs for suitable sites. Ultimately, this energy derives from heat in the Earth's core.
Three types of power plants are used to generate power from geothermal energy: dry steam, flash, and binary. Dry steam plants take steam out of fractures in the ground and use it to directly drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures over 200 °C, out of the ground, and allows it to boil as it rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine. In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine. The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat.
The geothermal energy from the core of the Earth is closer to the surface in some areas than in others. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such geothermal power sources exist in certain geologically unstable parts of the world such as Chile, Iceland, New Zealand, United States, the Philippines and Italy. The two most prominent areas for this in the United States are in the Yellowstone basin and in northern California. Iceland produced 170 MW geothermal power and heated 86% of all houses in the year 2000 through geothermal energy. Some 8000 MW of capacity is operational in total.
There is also the potential to generate geothermal energy from hot dry rocks. Holes at least 3 km deep are drilled into the earth. Some of these holes pump water into the earth, while other holes pump hot water out. The heat resource consists of hot underground radiogenic granite rocks, which heat up when there is enough sediment between the rock and the earths surface. Several companies in Australia are exploring this technology.
Geothermal Energy Prospects
The Geysers, is a geothermal power field located 72 miles (116 km) north of San Francisco, California. It is the largest geothermal development in the world outputting over 750 MW.
By the end of 2005 worldwide use of geothermal energy for electricity had reached 9.3 GWs, with an additional 28 GW used directly for heating. If heat recovered by ground source heat pumps is included, the non-electric use of geothermal energy is estimated at more than 100 GWt (gigawatts of thermal power) and is used commercially in over 70 countries. During 2005 contracts were placed for an additional 0.5 GW of capacity in the United States, while there were also plants under construction in 11 other countries.
Use of renewable energy has started gaining more importance in context of green house gas emission, global warming and ozone layer depletion. Also it is seen that the future has to depend on non conventional energy resources because conventional resources are depleting fast and may be extinct soon, so development of alternative resources has become a must.
In future the geothermal energy can be used for the following:
Community heating systems- the heating system can be used to keep a large group of houses hot during winters and hot water can also be passed through pipes to many houses using single connection thus bringing down the cost of establishment.
Production of small and large scale power- hot dry rock system, where water is passed onto dry rock in the deep layers of earth and heating the water for production of electricity. Since cleaner electricity can be produced it can be used in large scale. Small scale and large scale power production for various domestic and industrial use, can be done in the future.
Heating greenhouses- In agriculture greenhouses can be kept warm during cool climate and cool during hot climate using geothermal energy, so that productivity of the plants can be increased and pest and disease attack can be minimised. It is seen that 80% of fuel cost is reduced when geothermal energy is used and also 5-8% of operating cost is reduced.
In aquaculture – the water can be maintained at a constant temperature thus bringing in more productivity and healthier fishes. It also provides cleaner air and water for the fishes.
Industrial uses- In industries such as dehydration of vegetables like garlic and onion and fruits can be done using geothermal energy. In laundry industry hot water can be used, in pasteurisation of milk, gold and other metal mining.
Geothermal energy can also be used in swimming pools and in spas.
It is already seen that commercial use of heating geothermal systems are being used to heat the roads during snow. Pipes, carrying hot water is passed under the roads, which removes the condensed snow on the surface of the road.
More research can be done in context of improving conducting fluids and can be improved so that heat is retained for more time and the quality of energy is improved.
Air coolers and refrigeration- Methods to condense air and cool the air has also been developed. This can be used to bring about cooling systems for larger areas and also to refrigerate food items. Agricultural produce which require large areas under refrigeration can also be brought about.
With so many perspective uses of geothermal energy, the future is quite bright.
The earth absorbs more than 30% of the sun’s heat radiation incident in it in the form of infra red rays. This heat is captured and stored by it in its various components like the surface and underground water, rocks and other minerals and elements present in its different layers. This energy can be tapped and used for various purposes in our homes. Some of the common usage of geothermal energy in our homes, are given below.
We can use the heat generated from the earth’s surface for keeping our homes warm and cosy. This is very useful during extreme heat or extreme cold weather which is a commonly endured by many countries. We can use the geothermal energy of the earth, by tapping the heat using various different techniques.
The basic technique includes passing a geothermal fluid through a pipe into the crust of the earth, and absorbing the heat tapped there, this heated fluid is then passed through the pipe into the house thus conducting the heat into the house. The pipe used can be of metal or non metal, depending on the heat conducting fluid that we are using inside the pipe.
The fluid in the pipe is circulated through the pipe in cycles, bringing in cooler fluid and taking out warm fluid to transfer it on to the required place. Such pipes can be used in two different methods – geothermal heat pumps and geoexchange energy wells.
When the earth is used as source of heat the pipe brings heat into the house and when the earth is used as sink heat is taken from the house making it cool. The cycle can continue until we require and the energy required for running this cycle is also very low. Thus pollution free heaters as well non carbon emitting coolers can be obtained.
It is also observed that the cost of operation for such system is meagre compared to the electric room heaters and air conditioners used at present.
Another use of geothermal energy is by using dry steam in the pipes that are circulated in the house. The heated steam can be used to heat and cool the house. This heated steam can also be used to turn turbines to produce electricity to run electrical appliances of the house and also light the house. It can also be used to keep any greenhouse of the house warm. Dry steam can be used for cooking also. We can use dry steam to dry washed clothes during winter and rainy seasons.
When we use water in the pipes the heated water can be used directly to take bath, as we use solar water heaters, cook and also run turbines to produce electricity. The hot water also can be used directly to wash clothes, and in dishwasher.
Cooling systems can be used in refrigeration of different food items also. They can also be used during summer to keep the house cool.
It has been observed that the energy thus produced does not emit unwanted gases and is renewable.
The connection can be kept online 97% of the time without thinking of wastage as the wastage is minimal.
Geothermal Energy is the energy obtained from the heat stored in the deep layers of earth’s crust. It is a renewable energy and does not produce any harmful effluents as in the case of other fossil fuels. Its abundance and reliability make it more considerable for future power production. We can group the utility of geothermal energy into three- power production, ground source heat pump and use of derived heat.
The basic principle involved in tapping geothermal energy is that the heat from the deeper layers of the earth’s crust is brought to the surface layers by conduction of heat. The major resources of geothermal energy are the hot water springs found on the surface, the deeper rock surfaces and also the deeper molten magma.
We can classify the power production using geothermal energy into dry steam technology, flash steam technology and binary cycle system depending upon the medium used to transfer energy namely, dry steam hot water and geothermal fluid respectively.
Economically, geothermal energy has two phases, phase one involves the installation of the power plant, wherein as in the case of other renewable resources’ power plant the cost is quite high. This cost is due to the following factors:
1. Cost of land- large area of land is required for erecting various power production equipments, and also for drilling the land so as to reach the deeper layers to conduct the heat present there.
2. Cost of drilling- the land has to be drilled to a depth of at least 100 feet. It is done as that done in the petroleum pumps, because the basically the aim is to drill deep holes in earth.
3. Installation of machinery- various machinery, like driller, large pipes carrying the medium like steam or water , and other machines have to be installed for power production.
4. Cost of operation- these are the daily expenses. Operation involves the daily running of the machines, payment for workers, cost of inputs, etc,.The cost of electricity required to generate geothermal power is lesser compared to that of others like hydro electricity.
5. Cost of maintenance- every machine has a wear and tear and has got to be maintained for long periods. This does proves to take up a small percentage of the cost of production.
It is seen that the cost of production of power using coal is only US$ 0.02, but there is a large amount spent on the measures to minimise the pollution effects it causes, this expenditure brings the total cost of power to around US$ 2. This is very high as compared to geothermal energy.
The initial cost for the installation appears to be high in the case of geothermic power, but when compared to the charges of per capita power production using coal US$ 2, it is very less and rounds up to only $0.03 USD. It is seen that extra research to treat the effluents or to reduce pollution etc, are not required when we use geothermal energy. Also the long term uses are many such as- low to no effluent production, uses local energy so that import of raw material of any kind is not required, and also it is greenhouse friendly.
Geothermal energy is the energy produced by the heat within the surface of the earth. The innermost part of the earth produces an outrageous amount of heat. This heat is then transferred to the mantle, the layer of rocks that surrounds the innermost part of the earth. Due to excessive heat, this rock melts into magma, the molten rock. Molten rocks collect water and trap them to create columns or reserves which are called geothermal reservoir. By tapping into this geothermal reservoir, the resulting hot water and steam can now be used as energy for power generations purposes.
Geothermal energy produces little or no emissions at all. Steam plants use the hot water and extremely hot steam to power a turbine that supplies a generator directly called dry steam or they can lessen the very high-pressure and temperature of water to produce steam called flash steam. There may be a release with negligible amounts of carbon dioxide, nitrogen oxide and sulfur.
Geothermal power plants, once built, cost only very little to maintain and operate. They can be used as a direct heat source. Power can be generated by pumping water through hot rocks. Geothermal power plants have a very slight environmental impact. Geothermal energy system uses its capability to transfer heat. It only uses the abundant heat energy that is trapped below the earth’s surface.
There is no need to use crude oil to power up geothermal power plants which may contribute to air pollution. Geothermal energy systems are the most cost effective and most environmentally clean. After a short span of time, a geothermal power plant can raise funds more than enough to maintain and operate itself.
Underground heat pumps use pipes underneath the frost line to distribute a coolant through a cycle of compression and evaporation between two heat exchangers. One heat exchanger absorbs heat and evaporates at low pressure while a compressor presses the coolant vapor at high pressure to another coil where the coolant condenses and emits the heat. Heat pumps can perform in both directions- heating and cooling. Energy cost savings heat pumps are valuable.
However, geothermal sources are not always accessible. The hot rocks and water availability must be within drilling range. Geothermal sites may run out of steam because there is a tendency for temperatures to drop low. When there is a hot rock mismanagement, the water used may cool the rocks.
Furthermore, geothermal sources can also bring about harmful gases and minerals. Drillings into the ground can also cause earthquakes when water is pumped into the holes.
And last but not the least, several places which one may think as a potential site for a geothermal power plant, there is not much guarantee that it will yield enough energy to recover the amount of capital used for the construction and operation of the said power plant.
Basically, geothermal energy means heat from the earth. From the Greek word geo which means earth and the word thermo which means heat. Geothermal energy is energy which comes from the heat of the Earth. A massive amount of heat originates due to the chemical reactions which take place in the innermost part of the Earth. This heat build ups has a temperature as high as 9000 degrees Fahrenheit, and this outrageous heat can be utilized to produce energy.
Geothermal energy is a natural resource in abundant supply; it can be extracted from the earth’s ground. With the use of a geothermal heat pump system, and with the earth’s ability to store heat in the ground water, a heating and air conditioning system can be operated. Based on the constant underground temperatures, this heating and air conditioning systems can be operated. Due to this constant underground temperature, geothermal power plants can be work on any weather condition.
Geothermal energy has been used since time immemorial. The procedures used to utilize geothermal energy have always been comparably simple with that of other energy procedures, and the integral parts used are ordinary to everyone. The idea of using extreme hot water from the Earth's magma layers may seem too technical, but once you have drawn water from this resource, it would be easy to maintain it already and use it as a continual power source.
It is one of the most renewable forms of energy being used nowadays. Geothermal power plants can be operated by using only the abundance of heat energy that has been trapped in the earth’s underground. Geothermal heating and cooling systems are the most effective systems available and they are the most environmental - friendly and cost-effective conditioning system you can find. They can last longer than many traditional heating and cooling systems. In a span of few years of installation, they can be able to provide for its maintenance.
Geothermal energy consists of water which can be found below the surface. This energy comes from the earth's heat found below its surface. The crust of the earth is primarily the outcome of the past existence of many volcanoes and voluminous magma that failed to erupt but rather cooled below the surface. In addition, the innermost part of the earth has high temperatures between 50 and 60 degrees Fahrenheit that remain constant throughout the year.
This becomes an ideal source of heat which could be utilized for various purposes. These resources consist of the shallow ground, hot water and hot rock below the surface of the earth and the molten rock or magma deep down the surface of the earth. This magma becomes lava when it reaches the surface of the earth. There are two main categories of geothermal resources. The resources with high temperatures are found in the volcanic regions and the other which is of low and moderate temperatures are found in all the continents of the world. The resources with high temperatures are often used in power production.
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