Geothermal Energy is an energy resource obtained from the heat that is stored naturally in the earth's core. The heat stored may be due to volcanic activities and solar energy that is absorbed at the surface of the earth. It exists right from the formation of the planet and also due to radioactive decay. The ionizing radiation from the radioactive minerals and its disintegration constitute to geothermal energy. Due to meteorite impacts also, it can be produced. It is a non-conventional source of energy, so, it is eco-friendly, sustainable and a clean source. This approach drastically reduces global warming which is a much concerned issue among countries in the world. The process doesn't involve any green house gases thereby being environment friendly.
Types of Geothermal Plants
Flash Steam Plant
Hot water (350 degree Fahrenheit) from the reservoir is released at very high pressure and eventually the pressure is decreased and hot liquid, flashes in the form of steam. The steam thus generated, drive turbines. Dual Flash System is usually practiced to gain more efficiency. In dual flash cycle, the steam is separated at different pressures. The efficiency of dual flash system is 20% to 30% more than single flash system. There are various advantages of Flash steam plants such as low emissions and immune to all weather conditions. The largest flash steam system is in California and it is called Coso Geothermal Power plant.
Binary Steam Power Plant
This system operates at a temperature lower than Flash Steam Power Plants. It accepts liquid temperatures around 57 degree centigrade. A secondary fluid which has moderately lower boiling point than water is made to pass through the hot geothermal water. The secondary liquid gets converted into steam due to its low boiling point nature. The secondary liquid is mostly a hydrocarbon like Isobutane or Isopentane. The steam is cooled and injected again in a closed loop. This type of power plant is widely used these days.
Dry Steam Power Plant
Hot rocks that are 3 to 5 miles below the earth's surface can be used to produce thermal energy. Naturally occurring heat from the permeable rocks is used as an energy source. The permeability of the rocks can be increased by pumping cold water under high pressure down to the rock through injection wells. The pressurized water travels through the pores and the fractures present in the rock. The water absorbs heat from the interior of the rocks and the hot water is taken out through the second bore-hole. The steam from the hot water which is more than 150 degrees is converted into electricity, using steam turbines.
Future of Geothermal Energy
Power obtained from these sources is five times more than the total power of other non conventional sources of energy such as wind, solar, biomass and fossil fuels also. Due to technical difficulties, industrialists are not able to develop geothermal projects. Government provides good incentives for developing alternate non conventional energy sources of energy including geothermal energy. One of the additional advantages is that, useful minerals such as silica and zinc can be obtained from the underground extraction process. Also, direct use of geothermal energy can help in the reduction of coal and fossil fuels to several barrels.
David Blackwell, a geophysicist from Southern Methodist University, is very optimistic about the growth of this energy source. According to him, with sophisticated technology, geothermal could produce one tenth of power in US by 2050. US Geothermal Companies have huge projects and the government also promotes them. With upcoming advanced technologies, it can become a power source of energy in the years to come.