Global warming and climate change influence the choice of energy sources throughout the world. There is a growing emphasis on minimising the use of fossil fuels such as coal and petroleum oil & gas that emit carbon dioxide?the major cause of global warming?and increasing the use of non-conventional and renewable sources of energy. The Inter-Governmental Panel on Climate Change has identified India as a country likely to be most affected by global warming. Therefore, we need to act with the urgency that the problem deserves.
Fortunately, these concerns have led to increased use of renewable energy such as solar and wind power. India is one of the few nations that have created a ministry of new and renewable energy to encourage the use of non-conventional energy and minimise carbon emissions. The ministry has prepared a plan for the period 2010-13 involving a major increase in the use of renewable energy. The plan envisages setting up small/micro hydel projects, solar photovoltaic (SPV) power plants, SPV home lighting systems and solar thermal systems. This plan is expected to bring about aggregate savings of 20 million litres of diesel per annum.
Surprisingly, geothermal energy, which is available throughout the year, is not on the radar of the government of India. Even the recent order of the Central Electricity Regulatory Commission (CERC) directing electricity utilities to purchase green power to the extent of minimum 6% of their installed capacities, lists all renewable sources except geothermal. One can argue that currently, geothermal is not available; but if it is not even listed as an option, it would discourage its development by potential investors.
Geothermal energy is the natural heat freely available from within the earth. It manifests at the earth’s surface close to tectonically active regions, such as those close to the collision areas of tectonic continental plates. The movement of these plates creates subterranean faults and cracks that allow rainwater and snowmelt to seep underground and circulate back to the surface as hot springs and geysers. While these springs occur at natural cracks, technologies are available to harness geothermal energy for space heating and for generation of electric power. The US is the leader and generates about 3,000 MW of electricity from geothermal sources, including by private utilities; and in Iceland, over 53% of the total energy requirement is met by geothermal energy.
In India, more than 350 hot spring areas have been identified by the Geological Survey of India (GSI), with an aggregate potential of 10,600 MW. This is a figure that is five times the combined power being currently produced from all non-conventional energy sources such solar, wind, biomass, etc.
The areas with the maximum potential are in the Himalayan province lying on the collision zone between the Indian and Eurasian continental plates. The Puga hot spring area of Ladakh in northwestern Himalayas has been identified as the most intense and promising geothermal field of the country with a temperature of 240°C at relatively shallow depths. It is estimated to have the capacity to generate 30-40 MW of electricity. Panamik in Nubra valley and Demchok in Changthang are other geothermal belts in Ladakh, However, only an experimental 1kW generator is operational in this area and its output is being used mainly in poultry farming, mushroom cultivation, and pashmina-wool processing. This is in spite of the efforts of the Ladakh Renewable Energy Development Agency, which has been highlighting the geothermal potential of Ladakh.
At present, electricity generation for the region is either diesel-based or hydro-based. Studies conducted in 2005 showed that Ladakh required about 7,000 litres of diesel daily to meet its requirements for space heating and lighting. In addition, remote villages still depend on kerosene for lighting purposes. But these sources have their limitations, particularly in winters. Hydropower is unavailable due to freezing of waterways, while enormous costs are incurred in transportation and storage of diesel for the winter season, when the region is snow-bound.
The feasibility of geothermal generation of electricity in the Himalayan region on a larger scale has already been established by China. A geothermal plant has been operating since 1977 in Yangbhajain, Tibet, with eight double-flash units with a total capacity of 25 MW. Plants are also operating in Langju, Nagqu, Guangdong and Hunan.
Studying the experience of China and Iceland and keeping in mind the enormous potential identified by GSI, it is surprising why there are no plans to utilise the available geothermal energy resources in India. Development experts in India wax eloquent on the quantum increase in Bhutan’s GDP owing to its use of hydel resources and sale of electricity to India. They also suggest that Nepal should follow Bhutan’s example. However, they do not draw attention to the inexhaustible source of geothermal energy lying untapped within India.
