Geothermal, A Viable Alternative To Hydrocarbons For Power Generation And Climate Justice

Abstract

Oil and gas have a head start on various other forms of energy. They are easily transported, easily converted and, in today’s market still relatively available. But due to its exhaustible nature, more attention is now needed to develop alternative non- conventional energy sources in parallel to keep the energy requirements going. It is in this context that the geothermal resources stands out as a promising long term salvation due to its bounty in nature among various non-conventional energy sources in India. The 2015 Paris climate change agreement has set a long-term goal of keeping the increase in global average temperature to well below 2°C above pre-industrial levels, and the aim to limit the increase to 1.5°C. Energy efficiency is a key mitigation instrument. But efficiency alone will not be sufficient to reach this goal. Corroborating with the SDGs 2030 goals, we also need to look beyond efficiency improvements towards affordable and Clean energy (goal 7) and Climate action (goal 13). The paper identifies the viable alternative to hydrocarbons for power generation and climate justice. Geothermal exploration carried out in India, so far, has generated valuable data through extensive surface, geoscientific studies backed up by exploratory drilling down to depths of about 500m at selected geothermal localities generated valuable data concerning structural, geological, geochemical, hydrological and thermal parameters of geothermal systems. About 340 geothermal hot springs which are characterized by Tertiary and Quaternary orogenic activity in the Himalayas, Mesozoic and Tertiary block faulting and epiorogenic activity in the shield areas, and moderately active seismicity and intense neotectonism have been identified by the Geological Survey of India (GSI). A total of about 10,000 MW can be generated from Himalaya, Naga Lushai, Andaman-Nicobar Islands, West Coast, Cambay Graben, Aravalli, Son-Narmada-Tapi, Godavari and Mahanadi, South Indian Cratonic geothermal provinces which can be used for space heating and cooling, heating of green houses for cultivation, cooking, balneotherapy and the promotion of tourism especially in the high altitude and the colder regions in India. However, the geothermal reservoirs in India are of low to medium enthalpy type where surface temperatures vary from 800 to 105°C thus requiring a Binary Power Plant to convert their geothermal energy into electricity. Under the geothermal exploration program jointly executed by the GSI and the Oil and Natural Gas Corporation (ONGC) for experimental utilization of heat from thermal fluids, as many as 26 bore holes were drilled to depths varying from 100 to 620m in Central India. But, only five of the bore holes were found to be suitable for production as they were producing 60 litres of hot water per hour per bore hole at about 105oC. The ONGC has established a total of 300KWe electric generation potential based on the cumulative geofluid discharge of 1800 liters/minute at 1050C. This low to medium enthalpy reservoir will require the Organic Rankine Cycle based power plant to convert heat energy into electricity. Based on the Magneto-Telluric (MT) survey conducted by the National Geophysical Research Institute (NGRI), it is considered essential to go for deeper drilling down to 1500 to 3000m to obtain geothermal fluids of adequate temperature (about 2600C) and pressure for commercial exploitation. Such generation of electricity through geothermal resource is preferable due to its eco-friendly nature whereas much environmental hazards are associated with the coal and nuclear projects. A new development model of low carbon emissions is, therefore, now emerging in India as the clean renewable energy resources can provide the basis for sustainable energy development on account of their inexhaustible and environment friendly nature.

AAPG Datapages/Search and Discovery Article #90346 ©2019 AAPG European Region, 3rd Hydrocarbon Geothermal Cross Over Technology Workshop, Geneva, Switzerland, April 9-10, 2019