Published on June 20, 2021
AHMEDABAD: We may know about hot water springs at Tulsishyam or Lasundra, but there are 17 sites in Gujarat where geothermal energy can be exploited with good returns on investment, Gujarat’s first geothermal atlas highlights. The atlas was created by the Centre of Excellence for Geothermal Energy (CEGE) at PDEU, and is in the final stage before it is submitted to the state government for further exploration.
The 17 potential sites explored in Gujarat by the researchers are Dholera, Unai, Gandhar, Chabsar, Ghogha, Harsani, Kawi, Khedpada, Khar, Maktapur, Warha, Mithapur, Tuwa, Tulsishyam, Savarkundla, Lasundra and Lalpur.
Prof Anirbid Sircar, head of CEGE and dean of R&D at PDEU, said the results are encouraging with the majority of sites having medium to high enthalpy (total heat potential). “The sites were chosen based on geophysical surveys of gravity, magnetism, seismic activity and magneto-telluric surveys. In the majority of the cases, hot water springs are surface manifestation of geothermal energy,” he said.
The researchers went a step further with analysis of geophysical data to project possible energy values of the sites. “Temperature logs are also used to understand the subsurface gradients. An integrated geophysical data interpretation helped us identify the subsurface geothermal anomalies,” said Prof Sircar.
When commercial/ non-commercial entities harness geothermal energy, what factors do they consider? How do our sites measure up on those parameters? Prof Sircar said that they should consider the prognosticated energy resource for a particular site.
“Depending on enthalpy range and heat capacity they should decide whether it should be used for power generations or indirect applications such as greenhouses, horticulture, sericulture, food drying, honey processing, mushroom cultivation etc.,” he said. “In low enthalpy area, a hybrid approach can also be adopted. For example, we are exploring the solar-geothermal model in Dholera. Similarly, wind-geothermal model can also be adopted depending on the site conditions.”
The researchers said the atlas has shown potential to industry for both direct and indirect applications. They pointed to applications such as potato cold storage, milk pasteurization, honey processing etc. around such sites. They added that help from industries can demonstrate the commercial viability of such projects.
What makes Gujarat an important region to explore geothermal energy? Prof Sircar said that the Deccan traps are exposed in Gujarat. “The thickness of Deccan basalt varies from 400m to 1,200m. Deccan basalt can hold a lot of heat. If we can drill through it, we can extract a lot of heat from dry rock, a method known as an enhanced geothermal system,” he said, adding that the technique has successfully been used in countries such as Australia, France and the US.
CEGE is already working at Dholera and Unai. At Unai, the team has found the hottest well in Gujarat with a surface temperature of 70 degrees Celsius. The Centre of Excellence is also working on projects to showcase the capacity of geothermal energy for food drying and balneology (the medicinal effects of hot water springs).