Geothermal energy is derived from the natural heat of the earth. It is found from almost 4000 feet below the surface to the centre of the earth, and the deeper you go, the hotter it gets. The outer layer, the crust, is 3 to 35 miles thick and insulates us from the hot interior. Since heat always moves from a hotter region to a colder one, the earth's heat flows from the interior toward the surface. With high temperature gradients, there are deep subterranean faults and cracks that allow rainwater and snowmelt to seep underground sometimes for miles. There, the water is heated by the hot rock and circulates back to the surface as hot springs and geysers- fountains of hot water and steam.
Geothermal energy is divided into two categories. 20 to 150 °C is categorised as low to moderate category and above 150 C as high. Presently, it is being utilised for various economic activities such as soil warming, mushroom farming, space heating, hatching of fish, fish farming, swimming pools, biodegradation, fermentation, greenhouses, animal husbandry, vegetable farming, etc. Hot springs are regarded as one of the hidden, indigenous, clean, renewable energy. They can play an important role in boosting the living standard of the hillside residents by providing an energy resource, reducing greenhouse gases and promoting sustainable development on the basis of traditional as well as modern applications. In Nepal, there are more than 40 hot springs found in different parts of the country. All of them are mostly located on the banks of the Mahakali, Karnali, Tila, Kaligandaki, Myagdi, Marshyangdi, Trishuli, Singhya, Budi Khola, and Bhotekoshi rivers.
Energy sources
Hot spring resources can also contribute to developing our appropriate and indigenous proportion of energy resources. These geothermal resources are highly significant in developing nations like Nepal, where no fossil fuel resources exist, such as oil, coal, or natural gas. As the hottest springs are found in the remote and non-electrified areas, the people residing there will benefit greatly from this local energy. Singha Tatopati, located in Myagdi district and Kodari Tatopati in Sindhupalchowk draw people from different parts of the country. The maximum surface water temperature recorded as 55 C and 47.5 C from Singha Tatopani and Kodari Tatopani respectively. Similarly, the discharge rate of the hot water is 1.37L/S at Singha and 2.27L/S at Kodari. In addition, the two geothermal sites contain useful minerals. The recorded values for arsenic keep these hot springs well under the safety margin for human health. Thus, these hot springs have potential for therapeutic, recreational, and other economic applications.
More hot springs exist in Nepal besides the two above. But only a little study has been carried out on forty hot springs in the country. Some of them are partially used for medical treatment and recreational purposes only. Those hot springs contain different types of useful minerals such as sodium, potassium, sulphate, carbonate and chloride ions. The spatial distribution of the demand for energy adds one more dimension to the issues at hand. They are found in different climatic conditions; more than 80 per cent of them lie at the bases of the rivers of high mountains. The most of the hot springs lies between 80.6 east to 85.3 east longitudes and 27 north to 30 north latitude.
The range of rate of flow is about 0.2 to 8.0 L/s. Geothermal temperature is in the range of 37 to 115 in various locations of hot springs in Nepal. They are located in Darchula, Bajhang, Jumla, Rior, Surai Khola, Jomsom, Bhurung, Sandu Khola, Kharpani, Myagdi Singha, Bhulbhule Khar, Chilime, Syafrubesi and Kodari. But their potential has not been harnessed fully due to a lack of awareness and a proper action plan. The local and federal governments have not exploited them. Local communities and visitors extensively use them for traditional healing, relaxation, and the empirical treatment of skin ailments, joint pains, muscular disorders, gastric and rheumatism.
Chemical analysis
As per a recent study, the chemical analysis of hot water like PH value, calcium magnesium, bicarbonate chloride, fluoride, etc. were found very low in all locations based on the WHO guidelines. So the hot water in those places is drinkable. There is high potential to upgrade them into structured medical/wellness tourism hubs (balneology and hydrotherapy), which can directly stimulate rural economies in disadvantaged mountainous regions. This geothermal energy is environmentally friendly, so it can be used directly without any advanced technology. It can be exploited to boost economic activities with the help of low-level skilled manpower. Such types of activities are the construction of swimming pools, fish farming, heating soils, greenhouse farming, silk and wool dyeing and washing, livestock farming and mushroom farming, etc.
It is imperative to carry out a comprehensive study of all the hot springs throughout the country. Detailed geological surveys should be conducted for the purpose. Even though some hot springs have been studied for primary use, there is no sufficient authentic data available; therefore, the inventory needs to be updated. A database is necessary for further research and applications. Furthermore, radioactive effect should be measured and it is also essential to examine the microorganism test of hot springs. The local people and the local governments should be encouraged for building necessary infrastructures to tap these hot springs for the economic growth.
(The author is a director of the Gorkhapatra Corporation.)
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