| Abstract |
Geothermal exploration carried out in India, so far, has generated valuable data through extensive surface, earth scientific studies backed-up by exploratory drilling down to the depths of about 500m at selected geothermal localities concerning structural, geological, geochemical, hydrological and thermal parameters of geothermal systems. The geothermal provinces in India are located in area of high heat flow and geothermal gradients varying from 70 to 500m W/m3 and 60 to 2300C respectively. Some of the geothermal sites contain valuable gas contents like helium and other hydrothermal deposits little silver and gold. However, all the geothermal sites in India belong to low to medium enthalpy reservoirs (950 to 1900C) and thus, requiring an Organic Rankine Cycle Based Binary Power Plant of varying capacities to convert the geothermal energy into electric energy. The Tattapani Geothermal Field situated in Surguja district of Chattisgarh stands out among promising geothermal sites and has several hot springs with moderate gas activity and silica deposits around the vents of these springs. The surface temperature of the hot springs varies from 500C to 980C and their cumulative discharge is about 60 liters per minute. Under the geothermal exploration program for experimental utilization of heat from thermal fluids, as many as 26 boreholes were drilled for varying depths from 100m to 620m. Only five boreholes have been converted as production wells which have been producing hot water @ 24 tons per hour per bore hole at about 1000C. An electric generation potential of 300KWe using Organic Rankine Cycle Based Binary Power plant been worked out based on the reservoir parameters (long duration flowing and static temperatures and pressures) and the current price index together with other direct heat applications, namely, tourism, balneology, canning and fish farming to develop the economics of an otherwise economically poor Tattapani area. The MT survey conducted in the region has indicated the possibilities of primary deeper reservoir ranging in depth from 1500m to 3000m where high temperature gradient of about 200oC could expected for commercial exploitation. Though, at present the price of electricity is found to be slightly higher than the conventional one but such generation of electricity through geothermal resource is preferable due to its eco-friendly nature whereas much environmental hazards are associated with the coal or other conventional based projects. |