Assessment of Geothermal Renewable Energy with Reference to Tapoban Geothermal Fields, Garhwal Northwest Himalaya, India

Abstract

Abstract The energy potential of geothermal resources at Tapoban Geothermal Field, situated in the orogenic region of the Chamoli district of Uttarakhand state in the Himalaya, is investigated based on physical parameters, reservoir temperature, borehole depth, and geochemical indicators. It is a prospective field of geothermal water exploitation for both electrical and non-electrical usages. The anomalous geothermal gradient due to the active Main Central Thrust (MCT) zone plays a significant role. To explore the feasibility of exploitation, the surface water temperature and pH from existing geothermal springs is calculated, which ranged from 45°C-93°C and 6.2-7.3, respectively. The study based on dissolved silica geothermometry shows an average reservoir temperature of ~125 ± 2.0°C. The springs emerge from the prominent joint/ weak zone in the country-rock with the discharge of hot waters up to 300 liter minute-1. The total geothermal heat energy of the reservoir is estimated as ~874.35 x 1011 KJ. The energy estimated for the binary power geothermal plant is ~1.02 MWe and 0.71 MWe for 20 years and 30 years, respectively. This energy can be increased manifolds by operating binary cycle power plant technique at multiple sites for an electric generation. The heat capacity from two dominant hot springs from Tapoban geothermal resource was found to be ~0.84 MWt, which can be harnessed by the local people for direct usage. The annual energy use from this reservoir is ~15.89 TJ per year with a capacity factor (CF) of ~ 0.60, indicating that the energy reserve of the Tapoban geothermal field can be used for low to moderate scale energy production to partially meet the energy gap and future requirements.