**Abstract**

Proper utilization of geothermal energy for power generation is still overlooked in India even after having enough potential as much as the equivalent to its other nonconventional energy resources. The source of geothermal energy is the decay of the radio-nuclei present inside the Earth's crust apart from the primordial heat source. The noble gas <sup>4</sup> He is also produced during the radioactive disintegration process. Therefore, measuring the amount of <sup>4</sup> He gas along with some other geochemical parameters in an Indian geothermal area, the potential of the reservoir can be evaluated. Mathematical calculations relating to the radioactive disintegration to estimate the geothermal potential of Bakreswar geothermal reservoir utilizing the concept of the <sup>4</sup> He exploration technique has been described here. The study showed that the heat (radiogenic) energy generated by the radioactive decay of 232Th, 238U, and 235U inside the reservoir was evaluated as 38 MW. This value raises to 76 MW when primordial heat is included. The detail calculations suggest that a Kalina cycle based binary power plant using ammonia–water mixture as working fluid is supposed to be installed at the identified locations with a drilling depth of about 1,100 m and the plant would be capable of delivering the power of 9.88 MW to 40.26 MW.

**Keywords:** hot springs, radioactive disintegration, helium generation, geothermal power, geothermal power plant
