Introduction

Power generating units are mega project, which require not only huge capital investment but also various natural resources like, fossil fuels and water, thus create some impacts on the environment and generate a stress in the local eco system. Although stringent norms have been made by the regulatory agencies to control and mitigate the damages cost to the environment by the power plants, the efficacy and efficiency of the regulatory measures not been studied in detail. Therefore, a study was awarded by the Ministry of Statistics and PI to National Environmental Engineering Research Institute (NEERI). The study includes following three Thermal, one Gas and one Hydroelectric project.

1. Super Thermal Power Plant in Chandrapur, Maharashtra
2. Gandhi Nagar Thermal Power Plant in Gujarat
3. 600 MW gas based power plant of National Thermal Power Corporation at Jhenor- Gandhar, Gujarat
4. 100 MW Hydro-electric Project at Koyna, Maharashtra
5. Super Thermal Power Plant of National Thermal Power Corporation Ltd. at Ramagundam, Andhra Pradesh.

2. The study has assessed the environmental impacts caused by these power plants and has tried to monetise those impacts in order to facilitate a better understanding of the impacts. The external impacts pertaining to the air, water, noise, land, biological and socio-economic components of the environment are enumerated below.

Air Environment

3. Coal based thermal power plants affect the air quality of the surrounding region more than natural plants. Around the coal based plants the ambient sulphur dioxide concentration was in the range of 20-25 pg/m3 in and around Ramagundam. In case of Chandrapur Super Thermal Power Station the concentration of SO2 varied from 3.61-18.9 ug/m3 , NOx varied from 8.89-26.55 ug/m3 and SPM from 52.6-193.2 ug/m3. The concentration of SO2, NOx and SPM varied from 3-37, 5-34, 65-482 ug/m3, respectively in and around Gandhinagar Thermal Power Plant (GTPP) Ambient NOx concentration in case of natural gas based power plant was found to be in the range of 5-7 ug/m3 . From the epidemiological data of the area surrounding the Ramagundam coal based plant, it has been observed that around 6.5% of population living within a 2 km radius of the plant suffers from respiratory disorders, while the figure decreases to 3.2% at a distance of 2.5 km and becomes negligible (0.91%) at over 5 km from the plant. Thus it can be inferred that people living within 5 km radius of coal based power plant suffer from respiratory aliments.

4. The emission levels depend on the standards specified by the concerned State Pollution Control Board. The health effects attributable to NOx ,the Principal pollutant emitted from a natural gas plant even within a 2 km radius are negligible.

5. Although two other gases, carbon dioxide and ozone are not considered in traditional EMPs, the high amount of carbon dioxide emission (0.9-0.95 kg/kwh) from thermal power plants contribute to global warming leading to climate change is significant enough. Ground level ozone, which is formed due to photolytic reactions of NOx is not monitored in India and the paucity of accurate models to predict their levels, the impacts due to ozone cannot be quantified.

6. The normal operation of a hydroelectric plant does not affect the air environment. Latest studies have found that the levels of harmful greenhouse gases like methane emitted due to decomposition of vegetation submerged under water can be significant. Detailed research regarding such emissions is still under pregensis.

Water Environment

7 The water requirement for a coal-based power plant is about 0.005-0.18 m3/kwh while that for a natural gas plant is about 0.003 m3/kwh. At Ramagundam Super Thermal Power Plant (RSTPP) the water requirement has been reduced from about 0.18 m/kWh to 0.15m3/kwh after the installation of a treatment facility for the ash pond decant. At Chandrapur also major part of treated effluent is utilized for ash slurry preparation, while part of the ash pond overflow is discharged into the river.

8. The wastewater treatment facilities adopted by the thermal power plants are generally sufficient to attain the standards stipulated by the concerned regulatory authority, used in thecooling towers is generally disposed off at temperature 4-50 C above the prevalent surface water temperature, which can harm the local aquatic biota. In order to avoid such thermal pollution, the power plants dispose off the effluent by means of a long and open channel, due to which the temperature of the effluent comes down to the level of that of the surface water by the time it reaches the receiving body. Therefore, no loss of fisheries of other aquatic biota was observed due to thermal pollution by power plants.

9. Water slurry is used to take the ash from the power plant to the ash pond for disposal. There are two impacts associated with the ash pond decant. The first point is that this water slowly seeps into the ground while carrying with it the ash leachate. The water may contain harmful heavy metals like boron, which have a tendency to leach out over a period of time. Due to this the ground water gets polluted and may become unsuitable for domestic use. This point also could not be determined factually as there was no systematic testing of ground water for the presence of heavy metals. The second factor affecting the water environment is the release of ash pond decant into the local water bodies. At RSTPP, it was found that the ash pond decant leaked into a small natural channel and later joined the Godavari river. This could be because of bad dyke design or a deliberate attempt to dispose off the water without any treatment. Such release of ash pond decant tends to deposit ash all along its path thereby causing fugitive dust nuisance when it dries up. Also when such water mixes with a water body, it increases the turbidity of the water body thereby decreasing the primary productivity. This is harmful to the fisheries and other aquatic biota in the water body. Similarly in case of Chandrapur, though efforts have been made to recycle 100%, a part is still discharged into the river. In Gandhingar Thermal Power Plant(GTPP), the treated effluent is discharged into the non-perennial Sabarmati river. However, based on NEERI’s studies the authority have put up appropriate environmental management plants to reuse the treated effluent.

10. In the case of hydroelectric plants water environment is affected due to the stagnation of water in the reservoir. If the reservoir accumulates runoff from agricultural fields, the water may contain high amounts of fertilizer and pesticide residues, which may accumulate in the reservoir. However, in the case of Koyna Hydro Electric Project (KHEP), as it was at the upper reaches of its catchment, there were no agriculture fields at its upper reaches. Another point of consideration is that the formation of dam blocks the migratory path of certain fresh water fishes. In the case of Koyna river, since the water flow upto the site of dam was quite rapid, there was very small presence of fisheries. Therefore, there has been no loss to fisheries due to the construction of the dam.

Noise Environment

11. The exposure of employees to high noise levels is more in the coal based thermal power than in the natural gas based or the hydroelectric plant. In the case of effect of noise levels of the power plants on the local population, it has been observed that based on the stipulated requirements of various environmental bodies, the power plants have taken up sufficient measures like tree plantations to attenuate the noise levels outside their premises. However, the increased transportation activities due to the operation of the power plants have led to an increase in noise levels in the adjacent localities. But since transportation activities do not fall under the purview of the power plants, no specific measures have been taken for the same.

Land Environment

12. The land requirement per mega watt of installed capacity for coal, gas and hydroelectric power plants is 0.1-4.7 ha., 0.26 ha. and 6.6. ha. respectively. In case of coal based power plants the land requirement is generally near the area to the coal mines. While in the case of gas-based it is any suitable land where the pipeline can be taken economically. Land requirement of hydroelectric power plants is generally hilly terrain and valleys. Loss of agriculture land in case of gas based power plant was 168 ha. and hydroelectric was 230 ha. or 0.13 ha/MW. In case of coal based plants, the site was devoid of any forest while in case of gas-based plant it was primarily agricultural land. Loss of forest for KHEP was 1150 ha.

13. 321 ha., 2616 ha. and 74 ha. of land were used to dispose flyash from the coal based plants at Ramagundam, Chandrapur and Gandhinagar respectively. Due to this there is change in natural soil properties. It becomes more alkaline due to the alkaline nature of flyash.

Biological Environment

14. The effect on biological environment can be divided into two parts, viz. the effect on flora and the effect on fauna. Effect on flora is due to two main reasons land acquisition and due to flue gas emissions. Land acquisition leads to loss of habitat of some species. Los of such habitat or forests has not been there for the thermal power plants while in the case of hydroelectric plants, there has been a loss of 1150 hectares of forest land. However, in the case of KHEP there has not been any permanent loss of flora and faunal species due to land acquisition. The effect of flue gas emissions on flora is still being studied all over the world and only a limited amount of knowledge has been acquired of the same. Therefore, it is quite difficult to ascertain and quantify the impacts of such emissions on the flora.

15. In the case of Jhenor-Gandhar Gujarat Power Plant(JGGPP), it was found that the construction of raw water reservoirs has attracted a large number of birds into the area. Therefore, it can be inferred that the NOx emissions from the power plants have not caused any impact on the faunal species. In the case of RSTPP no such activity was found after the construction of the balancing reservoir. As the region is generally devoid of forests and therefore lacking in faunal species, no conclusion regarding the effect of flue gas emissions on the species could be reached.

Socio-Economic Environment

16. The study of the effects of a power plants on the socio-economic environment is based on three parameters, viz. Resettlement and Rehabilitation (R&R), effect on local civic amenities and work related hazards to employees of the power plants. The R&R required for the coal based power plant at Ramagundam was about 3761 persons (1.8 persons per MW of installed capacity), for hydroelectric plant was about 9069 persons (5.2 persons per MW of installed capacity) and was nil for natural gas plant. The R&R activities were carried out after giving suitable compensation to the affected people and therefore their costs have been internalized in the account books of the respective projects. These details were not available for Chandrapur and Gandhinagar power plants.

17. The development of civic amenities due to the setting up of any power project is directly proportional to the size of the project. The same has been observed to be the highest for the coal based plants followed by the natural gas based plant and lastly the hydroelectric plant. The work related accidents too follow the same pattern. The coal based plant has the highest number of accidents due to hazardous working conditions followed by the natural gas plant and the hydroelectric plant.

External Costs

18. External Environment Costs are about Rs. 0.1067 per kwh for RSTPP, 0.0646 per kwh for Chanderpur Super Thermal Power Plant(CSTPP) and 0.0614 per kwh for Gandhinagar coal-based power plants, Rs. 0.0202 kwh for natural gas-based power plants and Rs. 0.0054 per kwh for hydroelectric plants. For the purpose of evaluation, external costs can be differentiated into three major categories, namely ecosystem costs, agriculture costs and health costs.

19. Ecosystem costs are the costs due to damage accrued to the local ecosystem during and after the inception of a power project. This cost is negligible for coal-based and natural power plants and is Rs. 0.001 per kwh for hydroelectric plants. The ecosystem costs are mainly due to the loss of forests and habitats of wild animals as a result of land acquisition for the power plants.Also in the case of thermal power plants the cost of damage to the ecosystem due to air pollution is also a factor. But as the global database regarding the impacts of air pollution on forests and the ecosystem as the whole not comprehensive enough to allow for the monetization of the impacts, the same could not be carried out in this study.

20. In the case of damage to local aquatic ecosystem due to wastewater discharge, the quantification of impacts like loss of fisheries is possible only after an assessment over a certain time period or after comparison of pre-project and post project data. However, it has been seen that such data is not generated or mentioned by Indian power plants. Hence, the quantification of impacts to aquatic biota has not been possible.

21. The other damage due to land acquisition is to the agriculture sector. The loss of agriculture due to loss of land has been calculated to be Rs. 0.0002-0.0084 per kwh for coal-based power plants, Rs. 0.0007 per kwh for natural bas-based power plant and Rs. 0.001 per kwh for hydroelectric plant.

22. The cost of health impairments form an important chunk of the external costs of coal based power plants but such costs are absent in hydroelectric project and negligible in case of natural gas power plants. The cost of health effects have been found to be Rs. 0.00013-.047 per kwh of electricity generation in the case of coal based plant at Ramagundam and Rs. 0.001 per kwh for natural gas power plants. This data could not be quantified for GTPS.

23. Apart from the above mentioned three major external costs, the costs due to soiling of paints and plasters in the case of Ramagundam thermal power plant come to about

Rs. 0.00015 per kwh of electricity generation.

Assessment of Uncertainties

24. The total external cost of a power project has been found to be maximum for a coal based project at Rs. 0.1067 per kwh followed by a natural gas plant with external cost of Rs. 0.0202 per kwh and a hydroelectric project with Rs. 0.0054 per kwh as external costs. The high external cost of coal-based generation is mostly because of health impacts and global warming caused by the flue gases from such plants. These two costs account for about 39% and 0.48% respectively of the total cost of coal based generation. These figures are prone to uncertainty because of two factors. Firstly the sulphur content in coal varies from anywhere between 0.4% (found in some Indian coal) to about 4% (in some European Coal). The sulphur content in the coal of the case study considered here was about 0.6%. Any increase in this value will definitely have an incremental effect on the external cost. Second factor is the cost of global warming attributable to carbon dioxide and other greenhouse gases emissions. This cost is calculated in terms of Net present value of future damages due to global warming. This value depends upon the discount factor considered. As there is no global consensus on the use of a fixed discount rate, a range of $5 to $125 was suggested by IPCC for each tonne of carbon emissions. Hence the global warming costs, which have been calculated for $5 per tonne of carbon emissions, can only have upward mobility.

25. The cost of health effect due to Ramagundam coal-based power plant has been calculated at Rs. 0.047 per kwh. This value pertains to a semi-carbon region with maximum population concentrated with a 2 km radius of the power plant. For any rural setting, this value will go down, while for an urban site this value will increase. The same will also be true for costs of soiling of paints and plasters.

26. Another major factor of uncertainty in the case of thermal power plants is the installed capacity of the plant. Since the cost of impacts like health effects depend on the concentration of the various pollutants in the ambient air, the costs will increase proportionately with the installed capacity. This is because higher capacity power plants will discharge larger amounts of pollutants into the ambient air and therefore the associated external costs will also increase.

27. In the case of hydroelectric plants, the construction of reservoir is the principal source of external costs. The various costs like loss of forests, loss of agriculture, health effects etc.depend on the location and nature of the reservoir. If the reservoir is constructed in the upper reaches of the catchment i.e. in the hilly region, the ecosystem loss will be more compared to social loss. However, if the reservoir is constructed in the plains, the opposite will be true. Also less amount of area is required in case of dam on the upper reaches, wherein the reservoir become long and narrow, thereby not requiring extensive resettlement and rehabilitation activities.

Implications of the Results

28. The findings of this study on the post-clearance environmental impacts of various generation platforms can be utilized for not only understanding the environmental concerns but also for augmenting the existing environmental management plans for utilization by environmental law environment agencies and also for policies and decision making. However, in any case it should be understood that they are only broadly indicative of the type of power plants prevalent in the country and may not necessarily be representative of the ground level scenario of each power plant. Hence, instead of these results the methodology used for this study should be utilized in case of a requirement of external cost of any specific project.

Fixing Environmental Standards

Ø The results of the present study have thrown up some important aspects, which should be considered while fixing environmental standards for not only power plants, but other industries.

Coal-based Thermal Power Plants

Ø Emission standards should be based for the total quantity of pollutant emitted and not for the amount of pollutant per unit volume of emissions, as the present case.

Ø As it has been observed in the case of RSTPP and CSTPS plants, waste water treatment plant system may be modified so as to reuse the wastewater, which will decrease the water consumption to 0.15-0.18 m3 kwh of generation. Therefore, specific guidelines should be developed for the reuse/recycling of wastewater from thermal power plants.

Ø No specific guidelines exist for development of greenbelt in residential areas, the same should be developed so as to minimize the impact of air pollution on the surrounding population.

Ø In the case of pithead plants, instead of specially demarcated areas, the ash should be used to fill up discarded portions of mines, especially underground mines. Detailed guidelines for the same need to be formulated, which should also be applicable to the mining industry.

Ø Regular monitoring of ash leach ate for heavy metals should be carried out to check groundwater contamination.

Natural gas based Power Plants

Ø Use of low NOx burners should be made mandatory for natural gas power plants. These burners not only are more efficient than conventional ones, but also do not require steam irrjection for NOx control, thereby reducing water requirement.

Ø Recycle/Reuse of water should be made compulsory which will further reduce the water requirement of the plant.

Ø Extra treatment should be given to the effluent to reduce its temperature prior to its disposal.

Hydroelectric Plants

Ø Periodic monitoring of pesticides concentration in accumulated water should be made mandatory

Ø Daily monitoring of seismic records should be given emphasis

Ø Application of suitable measures for fisheries conservation should be undertaken.

Thermal Power Plants

Ø Health camps and free medical check-up should be encouraged for local population of at least 10 km radius from the plant site. Apart from the normal health check-up, emphasis should be given to specific diseases originating due to emission of different pollutants.

Ø Strict and regular medical check up with respect to hearing abilities should be made compulsory for the employees.

Ø A quarterly or half yearly monitoring of soil and the crops grown in the region should be done. Soil should be analysed for its fertility status. Types of crop diseases generally encountered, variation in the crop yield should be included in the report.

Ø Incase of thermal power plants, fly ash management should be given due importance. Double sprinkling systems should be employed to arrest the dispersion of dust particles.

Hydroelectric Plant

Ø During the planning stage due weightage should be given to Reservoir Induced Seismicity. At the time of construction phase, the contractors/builders should make use of materials which are more earth-quake proof. Regular monitoring of earthquakes should be undertaken during the implementation stage. General awareness camps for the local population should be held at regular intervals. People should be well informed about the emergency preparedness plans.