After reading this article you will learn about the use of geothermal energy in India with the help of statistics.
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It is a form of heat energy that confined within the earth interior through geological processes on a planetary scale. The presence of volcanoes, hot springs and other thermal phenomena must have led out ancestors to surmise that parts of the interior of the earth were hot.
However, it was not until a period between the sixteenth and seventeenth century, when the first mechanical mines were excavated to a few hundred meters below ground level, that humankind deduced from simple physical sensations that the earth’s temperature increased with depth.
At present, it estimated that total flow of heat from earth could be available above 42 x 1012 w. This heat flow generate primarily from radioactive isotopes of earth interior (viz., uranium, thorium, and potassium).
The first attempt at generating electricity from geothermal steam was made at Larderello in 1904. By 1942 the installed geothermal electricity capacity had reached 127,650 kwe–. During past two decades geothermal energy plays a significant role in electricity generation as well as non-electrical applications (Table 24.15).
Electricity generation is the most important form of utilisation of high temperature geothermal resources (7150°C). The medium to low temperature resources (<150°C) are suited for many different nonelectrical uses (viz., drying, heating, soil warning, distillation etc.).
Energy Use Pattern in India:
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The energy consumption in India was ranging between 356-425 Mtoe (or 14.9-17.8 EJ/year) in 1991, depending on the extent of biomass use considered for domestic sector. The share of biomass energy ranged from 36 to 46 per cent.
Among the commercial sources, coal was the dominant source of energy followed by oil and among biomass fuels, the most primary energy use per capita was in the range 17.7-21.1 GI/Yr, which is very low compared to the OECD countries (200 GJ/capita/Yr) (Table 24.16).
However, for all kinds of fuel use, demand is very much increasing with steady rise of population since 1970s.
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The details are given in Fig. 24.22:
The domestic sector dominates biomass energy use and fuel wood is the dominant source of energy in this sector in rural areas. Fuel wood is also used by urban households. Presently development efforts are mainly concentrated on fuel wood conservation and production, mainly for the domestic sector.
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Sectoral per capita biomass use in India is given in Table 24.17:
India is a large country with a geographical area of 328 M ha, with vast climatic variations and vegetation types ranging from tropical moist evergreen forest to dry deciduous forests and temperature maintain forests.
We can thus expect variation in the types and extent of biomass use according to agro- climatic zones, since biomass uses likely to be determined by local climate (temperature and rainfall), vegetation type, fuel wood availability and access to fuel wood.
The details are given in Table 24.18:
Among the biomass types, fuel wood is primarily obtained from the forest strands and as such rapid forest destruction takes place during 1960s to 1980s. To meet up these challenges, afforestation programmes were adopted particularly since 1980s in massive forms.
The sources of fuel woods as used in the domestic sector is given in Table 24.19:
The importance of crop residues as a source of fuel for domestic use has also been well-recognised.
Crop residues production and end use in India for fuel and fodder are given in Table 24.20:
The population in India (121 crores in 2010) is growing at a rate of about 1.76 per cent annually and it is observed that biomass use is keeping pace with population growth. The use of biomass as a traditional fuel is associated with a lower quality of life and environmental degradation.
It is thus necessary to understand what India is doing to alleviate such problems associated with the dependence on and use of biomass and to draw lessons therefrom before exploring the potential role for bioenergy in promoting sustainable development.
During past two decades enormous efforts were made to harness bioenergy sources in India to meet up the growing demand of energy for domestic use in particular, as such Department of Non-conventional Energy Sources (DNES) under the Ministry of Power & Energy was set up on 1982.
The major bioenergy programmes of DNES are:
India is a pioneer in biogas programmes, with the floating-drum biogas plant being developed in 1952. By 1993, about 1.85 million family biogas plants and 875 community biogas plants has been built.
The main goal of the biogas programme are as follows:
1. Provide cooking energy in a clean & non-polluting form;
2. Produce enriched manure to supplement the use of chemical fertilizer;
3. Improve the quality of life of rural women; and
4. Improve sanitation and hygiene.
Biogas (a mixture of about 60% methane and 40% CO2) is a combustible gas which is the product of anaerobic fermentation of cellulosic materials, such as animal dung and plant leaves and also washes from food processing and the household. Biogas can he combusted directly as a source of heat for cooking (calorific value 23 MJ/m3) or used with internal combustion engine for mechanical and electrical applications.
The slurry produced after digestion can be used directly as valuable manure for crop production. Two types of biogas designs are promoted in India—floating drum and fixed dome.
The characteristic features of these types are given in Table 24.21:
In spite of enormous potentiality of biogas development in rural areas, yet it is not developed as expected due to a number of barriers.
The crucial constrains are presented in Table 24.22:
Biomass, or more particularly wood, can be converted to a high-energy combustible gas for use in internal combustion engines for mechanical or electrical application. The process is generally known as gasification and the technology has been known for decades, but its application to power generation is of recent origin.
A biomass gasifier consists of a reactor where, under controlled temperature and air supply solid biomass is combusted to obtain a combusting gas (consists of H2 and CH4). This gas passes through a cooling and cleaning system before it is fed into a compression-ignition engine to run in dual fuel mode for generation of mechanical power or electricity (by coupling to a generator).
An assessment of its potential concluded that India presents a unique opportunity for large scale commercial exploitation of biomass gasification technology to meet a variety of energy needs, particularly in the agricultural and rural sectors.
The large potential of biomass gasification for water pumping and power generation for rural electrification was recognised and a research, development, and dissemination programme was launched during the period 1980-85.
Although initially a few programmes were launched based on imported designs, the Indian programme is now largely locally driven. A number of research and development (R & D) groups are working on the programme, and a number of designs of varying capacities have been developed.
The biomass gasifier programme in India is along the following lines:
1. R & D in biomass gasification technology;
2. Pilot testing and evaluation, including prototype production;
3. Demonstration and evaluation of biomass gasifiers;
4. Training and manpower development;
5. Commercialization and manufacturing.
Research and Development:
The ministry reports a number of achievements:
1. Wood gasifier designs of 5-100 kW capacity are developed and available for mechanical and electrical applications.
2. Gasifiers based on crop and plantation residues, such as rice husks, groundnut shells, cotton stalks and coconut shells are at various stages of development and field testing.
Demonstration programme:
A demonstration programme was launched in 1986 and about 800 gasifier systems of various ratings were disseminated, with a total capacity of 6.5 MW, until 1992 (Table 24.23). The majority of the systems are small wood gasifiers for irrigations, water pumping and some are used for electricity generation.
Though biomass use appears to be a potential material for energy producing raw materials in India for a long time, yet it is high time to evaluate the long term impact on environment arises due to biomass use.
It is necessary to understand the environmental implications of biomass use as an energy source via:
1. Contribution to deforestation and forest degradation, leading to loss of biodiversity and soil degradation;
2. Atmospheric pollution from emissions of greenhouse gases during combustion of wood, with its implications for climate change;
3. Release of pollutants (indoor air pollution) leading to domestic health hazards (particularly for women during cooking); and
4. Loss of nutrients due to combustion of cattle dung crop residues.
The renewable energy, the only sustainable form of energy in this country, has started receiving attention in recent decades.
The overall renewable energy generation potential and the quality actually harnessed in recent years is given in Table 24.24:
