Geothermal energy potential in relation to black carbon reduction and CO2 mitigation of Himalayan geothermal belt – A review

•The Himalayan geothermal Belt is manifested with hundreds of springs with issuing surface temperatures of 27 °C - 96 °C with slightly acidic to moderately alkaline (pH = 4.5 – 9.4) in nature.•The investigated geothermal systems are composed of a low to moderate enthalpy sources.•Puga, Chumathang, and Gaik thermal springs lie in the western part of HGB that correlate with the Yangbajing thermal spring in Tibet (the eastern part of HGB).•We have projected that the power potential of HGB is 23,622 MWe which can help to mitigate 1.4 × 108 tCO2. We have compiled geochemical dataset of springs (Thermal and Cold) from the Himalayan Geothermal Belt (HGB), shows slightly acidic to moderately alkaline (pH = 4.5 – 9.4) in nature with an emerging surface temperature of 27 °C – 96 °C. The calculated reservoir temperature ranged in between 78 °C – 159 °C categorize the HGB as a low- to a moderate-enthalpy geothermal system. It was observed that geochemical facies of thermal springs dominated by the Ca-HCO3, Na-HCO3 and Na-Cl composition while cold springs are abundant in Ca-Mg-HCO3 and Ca-Mg-SO4. Interestingly, Piper diagram inferred that Puga, Chumathang, and Gaik thermal springs, lies in the western part of HGB that correlate with the Yangbajing thermal spring in Tibet (eastern part of HGB). Tectonically, the HGB is associated with the continental collision zone, shallow crustal melting, and high heat-producing younger granite (70 mW/m2 to > 400 mW/m2); therefore, the resultant geothermal gradient along the HGB is more than 200 °C/km. The present research documents that HGB have potential to reduce CO2 and BC emissions by taping the geothermal energy for power generation and we have projected that the power potential of HGB is 23,622 MWe that can help to mitigate 1.4 × 108 tCO2.