The age of earth is estimated to be 4.5 billion years that is long enough to raise the temperature of its centre to 6000 degree Celsius. At this temperature the rocks beneath the surface of earth exists in melted form. Going down the surface of earth a few kilometers can encounter us with a temperature of 250 degrees Celsius and even more. For every 30 to 50 meters the temperature of earth increases by one degree. These melted rocks are far closer to the surface in volcanic areas and there heat can be used as an energy source.
The origin of word Geothermal is Greek: Geo means ‘earth’ and Thermal means ‘heat.’ The estimated geothermal energy is far greater than the total amount of energy generated by all fossil fuels. The subterranean hot rocks can be used in heating the water to transform it into steam. Holes are drilled into the hot part of the earth and water is sent down. This water comes up after converting into steam and is utilized in running turbines that in turn run the electric generators. This steam must pass through filters before driving the turbines or it will fur up the blades.
|Note: This image shows how one of the type of geothermal power technology works and produce electricity to light up a electric bulb||Note: Very good video for understand how geothermal power plant works to produce electricity
There are three types of technologies that are used in geothermal power plants: Dry Steam, flash and binary cycle. State of the fluid used in the process decides which type of technology suits best.
- Dray Steam Power Plants use the steam that comes straight from the geothermal reservoir and send it on the routes to generators so it may create electricity. They are the first type of geothermal stations.
- Flash Steam Plant is now the most common technique. They utilize water of more than 182 degrees Celsius and needs high pressure to pump the water to turbines.
- Binary Cycle Power Plant never lets the heated water in coming contact to the electricity generating generators.
Landrello, Italy was the first place where first geothermal power station was installed in 1904, where Wairekei, New Zealand, was the second destiny to have one. Unites States, Japan, Iceland and Philippines also have geothermal stations of their own. Interestingly, these stations are used to not only generate electricity but also heat homes in Iceland.
The usefulness of the system depends on the temperature to which we can heat the water. The output depends upon the energy of the innermost rocks and the quantity of water pumped down.
Let us have a look at the advantages of geothermal energy resource.
- The source of this energy is earth that is capable of maintaining its temperature. It is one of the best renewable sources of energy.
- The heating cost in this system is very low. Almost 60 per cent less fossil fuel is required to run the geothermal power plant.
- The plant uses far less electricity than the conventional heating system.
- It is also one of the best ecological solutions as the emission of pollutants is very low and no green house gases are discharged.
- The efficiency of this power plant is far greater than other heating systems. It is 75 per cent more efficient than the oil furnace and 48 per cent more efficient than the gas furnace.
- The system is not only used for heating a place but also for cooling down the site. It generates uniform energy that means there are no cold or hot spots and needs no outlet like chimney for discharging the waste.
- The system functions quietly and thus create no sound pollution.
- Maintenance of the geothermal plant is very cheap. The air filter of heat pump unit is the only article that needs replacement.
- This system can also used in existing houses if the life of their underground piping is more than 50 years. The place should also have a forced air dust system.
There are also disadvantages that are associated with the geothermal power plants. Let us have a look at them:
- The system has very high installation cost that makes it impossible for a number of people to benefit from the clear technology. It is estimated that the installation cost is sometimes paid back in two years and at times in 10 to 20 years.
- The plant needs large yard for its installation and some pond or well as a reserve of water. The system proves impossible at some places due to its incompatibility.
- The geothermal power plant cannot be installed by all and sundry. Only authorize technician can access and install the system which in terms means high labor.
- The energy generated is not 100 per cent clean as coal is used for electricity which in turn emits hazardous green house gases like carbon dioxide.
Although scientific development is needs but the magma of the earth is potent enough to meet the needs of human kinds. It is expected that the few disadvantages will be soon covered by the scientists and the ultimate sources of energy will be made accessible to those countries that are non-volcanic.