Study of Economic Feasibility for a Decentralised Small Off Grid Geothermal Power Plant Using Slim Boreholes

Abstract

India’s 80% of the electricity demand is fulfilled by exploiting non-renewable fossil fuel. India’s dependence on energy imports will exceed 53% of the country’s total consumption by 2030. To curtail this alarming increase of dependence on fossil fuels' attention towards the development of renewable resources like Solar, Wind, Hydropower, and Geothermal is needed. The major aggravating factor that flags the development of renewable power plants is 65% of the population residing in remote areas. This makes transmission of electricity a major issue for remote areas as most of the power is lost in form of heat over long distances from power plants. This paper shows a case study of Himachal Pradesh, India discussing the feasibility of a decentralized Small off-grid Geothermal power plant for providing electricity to remote areas. According to a study, Himachal Pradesh Geothermal Sub- provinces (HPG) is a fraction of the large Himalayan Geothermal Province extending up-to 1500 sq. km. High thermal gradients ( more than 260℃/km) and High heat flow( more than 180mW/m2) are the characteristics of HPG. Additionally, Surface spring temperature of 57 to 98℃ at Manikaran, Himachal Pradesh corroborates the high potential reserves of geothermal sources beneath the strata. Thermal water flow rates measured from the shallow exploration bore wells, drilled by the Geological Survey of India, varies from 200 L/m (52 GPM) to 1000L/m (264 GPM) is far greater than the 2.5 – 3 GPM required for the production of 12000 BTU/hour. The use of slim boreholes (150mm or less) will reduce the drilling cost for the extraction of thermal waters further increasing the possibilities of off-grid geothermal plants for rural electrification. This paper also presents the approximate economic cost required to set up a geothermal plant at a remote location and studying the minimum load required for the plant to be feasible for local populace.