Till a couple of decades back geothermal energy was not playing any significant role in the scenario of world energy production. Even now, it hardly constitutes 1% of the total electricity output. Lately, however, geothermal energy scene is changing very fast with a rapid spurt in its direct and indirect use, primarily due to Eco-friendly, renewable and pollution free character. Also, geothermal resources are abundantly available throughout the globe.
Geothermal water has a temperature appreciably higher than that of the local average annual air temperature. However, in general, a spring is considered hot when its temperature is about 12.2 0c higher than mean annual ambient temperature . The relative terms geothermal water, warm springs and hot springs are common.
Geothermal water discharges from numerous springs located mostly in mountanious or plateau areas. The springs are connected by faults to deeply buried reservoirs that contain geothermal water, which moves upward along the fault zones to discharge at the land surface. Much geothermal water discharges as hot springs that flow steadily instead of erupting at intervals.
One theory use to explain how geothermal water becomes heated in areas that are underlain by complex geologic structures is that when precipitation falls in highland areas recharges the aquifer system. Some of the water moves downward along faults and fracture zones to great depths. As the water descends, it becomes heated because of the geothermal gradient. At some depth, the heated water becomes lighter than the overlying water and then moves upward along faults to discharge as spring flow.
Jharkhand has the good reservoir of geothermal energy in its earth’s interior, whose surface manifestations are the steaming grounds and hot springs. The hot springs in Peninsular Shield of Jharkhand are located along a zone running more or less parallel to Damodar Valley Coalfield, i.e. along faulted boundaries.
In Jharkhand the thermal springs are found in Tatta- Jarom of Palamau district and Surajkund, Duari, Bagodar of Hazaribag district. The Tatta spring occurs within the Gondwana rocks and Jarom occurs within Proterozoic rocks. The temperature of the thermal discharge at Jarom is 50 degree c. (centigrade) to 57 degree c. while at Tatta it varies from 61 degree c. to65 degree c. in different spouts. All the thermal springs in Hazaribag district are grouped in Damodar valley graben geothermal province.
Needless to emphasis that geothermal energy is presently recognized as the only one of the so-called alternative renewable energy resources which is technically, commercially and economically viable for generation of electricity. There is another important aspect. Unlike, other power projects-a ‘geothermal plant’ has a minimum negative impact on the environment. It is thus necessary to promote such alternative sources in Jharkhand to combat with power crisis.
Surajkund main spring in Hazaribag district records the second highest temperature 88 degree c. after Tattapani hot spring of Madhya Pradesh. The other hot springs are Lakshmikund (53 degree c.), Brahmakund (45 degree c.), Ramkund (62 degree c.), Satrughnakund (68 degree c.) and Sitakund (53 degree c.) and they discharge thermal fluids up to 4 liter per second. Tatta discharge 2.1 liter per second and Jarom discharge 1.8 liter per second.
Most of the hot springs of Jharkhand are not potable due to high concentration of floride. Concentration of Helium is highest in the thermal gases of Surajkund. Where as Methane is highest in Barkagaon. In Jarom Mercury concentration in soil around the hot springs varies from 20 ppb (parts per billion) to 125 ppb. Cawa Gandhwani and Duari hot springs are more radioactive.
Excessive concentration of certain dissolved minerals in geothermal water pose water-quality problems. The most common of these minerals are dissolved fluoride, arsenic, and iron. Concentration of dissolved fluoride in excess of 4 milligrams per liter can cause mottling of teeth, especially children’s and can cause bones to become brittle.
The geothermal energy can be used for space heating, development of cold storage for preservation of bio and agro products, setting up of plants for drying, processing, preserving and canning of fruits and fruit products.
The hot springs in Jharkhand are situated mainly in hilly tribal belt or in isolated and remote region of the state. Obviously these rural areas are backward and poor. The energy needs of the people of rural and backward area are primarily for irrigation, farm inputs, processing and preservation of agro products, cooking, lighting and space heating. Hot spring water of low temperature has been directly used for irrigation of field/farm and to increase the soil temperature for obtaining early maturity and bumper crops as done in China and Russia. Waters of low temperatures of hot springs can be directly used for irrigation of field/ farm to increase the soil temperature for obtaining early maturity and to increase production of vegetables and mushroom growth under controlled conditions. The hot springs area can also be used for development of tourism and health resorts.
Regarding Helium concentration assessment of Helium reservoir may be undertaken in the area studied to see if Helium can be mined and Methane content may be evaluated to determine whether it is a usable resource in the region.
As a matter of fact, our resources are quite similar to that of China, who are exploiting them on large scale. They rank number one in installed thermal power capacity. It is, therefore necessary to give serious thought to exploit our resources too, at least those situated in power starved hilly areas, where due to lack of infrastructure and adequate demand, conventional power plants would not be economically viable.
Dunn, J.A., 1942, The economic geology and mineral resources of Bihar Province: Mem. Geol. Surv. India, v. LXXVIII, p. 197-204.
Ghosh, P.K., 1954, Mineral springs of India: Rec. Geol. Surv. Ind., v. 80, p. 545-558.
Prasad, J.M., 1996, Geothermal energy resources of Bihar, in U.L. Pitale, and R.N. Padhi, eds., Geothermal energy in India: GSI special publication 45, p. 99-117.
Priyadarshi, N., 2002, Potential of geothermal energy in Jharkhand State, India, in Proceedings of the 1st conference and exhibition on strategic challenges and paradigm shift in hydrocarbon exploration with special reference to Frontier Basins, held in Mussoorie, India. Published by Association of Petroleum Geologists, v. 2 p. 261-265.