Prof D Chandrasekharam

“Deriving energy from subterranean heat is no longer limited to volcanic regions. By drilling deep wells into the ground, it can be made to work almost anywhere. Engineered geothermal systems (EGS) are based on a related principle, but they work even in parts of the world that are not volcanically active, by drilling thousands of meters underground to  mimic the design of natural steam or hot-water reservoirs. Wells are bored and pathways are created inside hot rocks, into which cold water is injected. The water heats up as it circulates and is then brought back to the surface, where the heat is extracted to generate electricity. Because the Earth gets hotter the deeper you drill, EGS could expand the reach of geothermal power enormously and provide access to a virtually inexhaustible energy resource” states a news item on “HOT ROCKS AND HIGH HOPES” (Inside story) in “The Economist” dated 2 Sept. 2010.

 Geothermal systems are based on circulating hot water, heated either by volcanic or tectonic ( deep continental rifts) systems. Such system where natural rain water circulates is known as wet geothermal systems.  As on today, according to the recently concluded “World Geothermal Congress 2010,  10,700 MWe of power is being generated from geothermal energy supplying 85 million Gwhr of electric power.                                                           

The future energy need of all the countries will be met with by EGS systems.  For example, 2% of the energy (EGS) if tapped will be sufficient to meet the energy demand of United States of America, according to “  The Future of Geothermal energy “ of MIT 2006. Currently  Soultz EGS systems has started functioning successfully. This will soon be followed by the EGS system in the Cooper Basin of Australia.

 “……….Over the next decade Geodynamics plans to build ten 50 megawatt (MW) power stations in Cooper Basin, and that may just be the beginning. According to Doone Wyborn, the company’s chief scientist, the area’s resources could support  hundreds of power stations with a total generating capacity of up to 12.5GW—more than all the geothermal power stations now operating worldwide……………… These benefits, in combination with growing electricity use worldwide, concerns about limited supplies of fossil fuels, and efforts to reduce carbon-dioxide emissions and prevent climate change, have prompted governments and investors to pour money into this emerging technology. Google, for example, has invested more than $10m in two EGS companies in California, Potter Drilling and Alta Rock Energy. Meanwhile America’s Department of Energy has announced up to $338m in stimulus funds for 123 geothermal projects, with nearly $133m earmarked for EGS research……………………” states  the above magazine.

 EGS technology is more or less well established. Following France and Australia other countries like Germany and England are lined up to harness this heat. 

 India is not lagging behind EGS resources. Perhaps, India has the richest EGS resources considering the volume occurrence of high heat producing granites.  About an year ago, in a publication entitled “ Granites and granites: India’s warehouse of EGS” in Geothermal Resources Council’s Bulletin followed by a recent proceedings published by the World Geothermal Congress 2010, it is stated “ Assessment has been carried out on the power producing capacity of thee granites using the U, Th and K content. For example, estimates on a small volume of granite from northern India indicate that they have the potential to generate minimum of 61160 x 10¹² kWh. Perhaps EGS, in future, may make India energy independent and wipe out the 78,577 MWe deficit.  Considering the total surface exposure of such high heat generating  granite over the Indian subcontinent (150000 sq. km), their depth of occurrence and the stress regime of the Indian plate Indian granites will be future warehouse of EGS…………… Indian government has realized this potential and making efforts, through slow, in bringing geothermal under the primary source mix. India in future can  disprove the IEA (2007) report that it will a major coal importer in 2030 if its geothermal resources are judiciously utilized not only for power generation but also in building and food processing sectors”…………states these publications.