The temperature rises one degree Celsius for every 30-50 meters you go down the earth’s surface. This 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. This heat energy is called geothermal energy. Geothermal energy can be defined as a sort of renewable energy derived from the heat generated deep in the earth’s crust. This clean and sustainable energy has been used for thousands of years in some countries for cooking and heating. As groundwater is heated, geothermal energy is produced in the form of hot water and steam which can be used for direct heating of homes and greenhouses.
Production of electricity
Geothermal resources have been harnessed as an energy source in earlier times and can now be tapped to generate electricity. Geothermal electricity generation technologies consist of three methods: dry steam method that uses steam as it comes from the underground source to drive the turbines, flash steam method which makes use of the underground hot water (360 degrees F) is pumped to the surface where it flashes to steam and drives the turbines and binary method that makes use of heated underground water and runs it through a heat exchanger where it heats a fluid with a lower boiling point that flashes to steam and drive the turbine.
Electric power plants driven by geothermal energy provide over 44 billion kilowatt-hours (kWh) of electricity worldwide per year with United states, Philippines and Indonesia producing the majority. Currently only 24 countries have geothermal power stations.
Can this be better?
The amount of geothermal energy stored deep in the earth is much greater than the amount of energy that humans use. The efficiency amounts to only 10-23%. But that energy is not easily accessible. The efficiency of engines that convert heat to energy is limited due to thermodynamic laws. The heat that is rejected by the power plant goes to waste when exhausted into the environment which can be used in green houses, mills and also in local houses. On the other hand, their engines are not the theoretical perfect engines, either. Since geothermal energy is an independent resource its efficiency can be much larger if used in a proper way.
A major drawback to geothermal energy is finding a suitable build location. An ideal site for drilling a well in order to trap geothermal energy must provide hot rocks in the layer of the Earth’s crust that would heat the water pumped into the well at suitable level. Such a project may only be useful to provide electricity or heat to the local area only if the area is remote. After finding the location its quite uncertain to say whether the geothermal area is active or not. The location may remain active constantly for several years and then stop for a few months. Hence not all locations are completely reliable.
Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations, but capital costs are significant. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks. A typical well doublet (extraction and injection wells) in Nevada can support 4.5 megawatts (MW) and costs about $10 million to drill, with a 20% failure rate.
Another arguable disadvantage of converting to geothermal energy is a high installation cost. Combined with current state and federal incentives, geothermal installation costs are extremely competitive with conventional fossil fuel systems. The development of geothermal reservoirs is often unfeasible because they are too far from major population centers. This adds to the cost of transmitting electricity, which is higher over long distances.
Can this be avoided?
Almost all other energy sources have some limitations based on locations. It is not only the case with geothermal energy sources. Geothermal is a renewable energy resource deriving energy from the heat of the earth’s core and volcanic-thermal activity. The Earth’s core will continue to produce massive amounts of heat for millions of years which can be harnessed by humans. The installation costs are though high, but they can easily be offset with savings on utility bills and possible rebates from your local electric company. Moreover the cost of the geothermal electricity has been lowered to 50% since 1980.
Hazardous Materials and Earthquakes
The ugly part of geothermal energy is the hazardous gasses and minerals such as mercury, hydrogen sulphide, ammonia and arsenic come upon the surface along with hot water. These materials, which could cause environmental pollution, are not easy to deal with. It’s another disadvantage is the possibility of natural earthquakes which may cause damage to the power plant and also local residents.
Why are we so critical?
The several geothermal power plants in existence use hot spots on the earth, where the temperature is much higher than the 150 0F. Geothermal power in the long run is seen to be very cheap, but the initial cost of installing the power will definitely be high.
Harnessing geothermal energy requires a small piece of land and freshwater. But this energy can be along with with dangerous risk of carrying a mixture of gases such as carbon dioxide, hydrogen sulphide, methane and ammonia which can add to global warming, air pollution, and acid rain. Various poisonous minerals like arsenic and mercury also come to the surface, thus polluting underwater and soil.
The Bottom line:
Since geothermal energy is a renewable source of energy, it will soon become popular and much cheaper. But the geothermal areas are limited therefore this energy source will not be beneficial worldwide.