Environmental impact of coal industry and thermal power plants in India
Introduction
When India got independence in 1947, the total installed electricity generating capacity in the country was less than 1500 MWe. This capacity had to be increased rapidly to meet the industrial, domestic and agricultural requirements of a very large population. Today, the installed capacity is more than 90,000 MWe and it is growing rapidly. More than 70% of this power is generated from coal. The only fossil fuel available in abundance is coal, and hence its usage will keep growing for another 2–3 decades at least till nuclear power makes a significant contribution. Many mega hydro-projects were taken up in 1950s and early 1960s, which are contributing about 25% of the power. However, now such projects meet tough opposition from environmental groups and are difficult to complete. At present, only two big hydro-projects (one in northern India called Tehri and the other in central part called Narmada) are under construction and are expected to start generating power within the next 1–2 years.
The coal available in India is of poor quality, with very high ash content and low calorific value, and most of the coal mines are located in the eastern part of the country. This requires long distance transport to power stations located all over the country. In view of the above facts, a long-term study was taken up by the author’s laboratory more than a decade ago. There are three aspects to this study.
- 1.
Eisenbud and Petro (1964) first pointed out that the radiation dose from the use of fossil fuel for power generation could be a significant addition to the natural radiation dose. Hence, the first aspect of our study was to measure the natural radioactivity content of coal and fly-ash from more than 30 power plants and in coal samples from coal mines. In two plants, one using coal and the other lignite, actual external gamma dose was measured using scintillometers. The first results were reported in 1980 (Mishra et al., 1980). At the end of this phase, all the results were summarized in 1989 (Ramachandran and Mishra, 1989), and findings were given in an invited paper in 1991 (Mishra, 1991). Comparison with the radiation dose from nuclear power plants (NPPs) of similar capacity and the methodology adopted for dose estimation were given in an earlier publication (Lalit et al., 1986).
- 2.
The second aspect of the study was to estimate the overall impact of gaseous and particulate pollution caused by coal-based and nuclear power plants to assess the impact of the coal and the nuclear fuel cycle.
- 3.
The third aspect was to recommend remedial measures, as use of coal cannot be dispensed with, as mentioned above. In this phase, the aspect that is still not satisfactorily resolved is the health impact of the two types of power plants. The author’s approach in this regard was presented at an IAEA conference at Vienna in 1994 (Mishra, 1994).
Section snippets
Coal quality
Even though coal is available in abundance, its quality is poor. Whatever good quality coal available is used by the metallurgical industry, like steel plants. The coal supplied to power plants is of the worst quality. Some of the coal mines are owned by private companies, and they do not wish to invest on quality improvement. Table 1 gives the wide range of parameters found in different coal samples. Further, in the eastern parts of the country, where most of the coal mines are located, coal
Measurement techniques
Coal and fly-ash samples were collected from more than 30 power plants from all over the country. Samples were measured for their radioactivity content by gamma-ray spectrometry using a 12.5 cm×10 cm NaI (Tl) detector and concentrations of U-238, Th-232, Ra-226 and K-40 were estimated using standard procedures. Coal samples were also collected from coal mines and measured by the above procedure.
Results and discussion
A summary of a very large data set of measurements on coal, fly-ash, slag and ambient soil samples is given in Table 2. The external gamma radiation dose measured at different locations of two power plants carried out by a scintillometer type survey meter at 1 m height is given in Table 3. It can be seen that fly-ash dumps are the places with the highest radiation dose.
Problem in health risk estimation
Nuclear power plants emit radioactivity and negligible amounts of gaseous or particulate pollutants. The risk associated with nuclear radiation is probabilistic. On the other hand, thermal power plants using fossil fuels produce particulates, oxides of sulphur, nitrogen, carbon and toxic metals like arsenic, mercury, etc., in trace concentrations. The health risk of all these is deterministic. The end points are also different. In the case of the former, it is the probability of causing cancer,
Conclusions and recommendations
- 1.
Natural radionuclides in coal samples are of the same order as in the ambient soils. However, on combustion, some of the radionuclides get enriched by factors of 2–5 in fly-ash.
- 2.
The natural radiation dose to population from thermal power plants studied is slightly higher than from nuclear power plants of the same capacity, due to very high ash content and higher population density around such plants.
- 3.
The radiation dose from thermal power plants can be very much reduced by reducing the ash content
References (6)
- et al.
Radioactivity release to the environment by thermal power stations using coal as fuel
Science of the Total Environment
(1980) - et al.
Radioactivity in the atmospheric effluents of power plants that use fossil fuels
Science
(1964) - et al.
Radiation exposures due to coal fired power stations in India
Radiation Protection and Dosimetry
(1986)