Helium from Geothermal Sources

Abstract

Helium is a remarkable element possessing a broad bandwidth in the field of its application. It plays an indispensable role in many areas of fundamental research (cryogenics, nuclear science, material science), cutting edge technologies (nuclear reactors, space and rocket science, balloon and aerostat), medical diagnostic imaging (MRI), besides a host of other crucial uses. Presently there is a worldwide scarcity of helium supply. As of now globally the major source of commercial helium production is the petroleum natural gases. In Indian context, the natural gas reservoirs are lean in helium and India imports 100% of its total helium requirement. However many of the Indian hot springs are enriched in helium and may serve as the potential and indigenous source of helium. Indian geothermal provinces which are associated with high heat generating granites like those occurring in Bihar, Jharkhand, Chhattisgarh, West Bengal, Uttar Pradesh, Madhya Pradesh, Maharastra, Rajasthan and Karnataka are rich source of helium due to the high concentration of uranium in such granites. The helium content in the hot gases from Bakreswar and Tantloi (West Bengal-Jharkhand states) geothermal sites varies from 1-3% v/v. The volume of gas that escapes from the hot spring vents and the wells drilled in the above sites is 130 L/h and the flow rate of thermal water is 21000 L/h. Helium exploration field stations were also established in the above mentioned two sites. Hot spring gases are collected in cylinders and subsequently purified to the extent of 99.9% v/v. The temperatures of the thermal waters vary from 70-75 C. The geothermal gradient and heat flow rate values of the Bakreswar-Tantloi geothermal area are 80 C/km and 200 mW/m2, respectively. It is proposed to drill an exploration cum production well in this geothermal to generate electricity using hydrothermal waters and to recover helium through installation of a large scale pilot plant.