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Indian Thermal Power Plants Must Use Beneficiated Coal, Shri R V Shahi, Former Secretary, Ministry Of Power

Indian Thermal Power Plants Must Use Beneficiated Coal
[R V Shahi's Weekly Column for Infraline, November 5, 2007]

I recall having visited a large number of coal based power plants in USA and UK way back during eighties and nineties. Both these countries have had significant dependence on coal based power generation. USA even now has more than 50% of its generation on coal. Until nineties even UK had more than 60% of its power generation on coal based thermal power plants. Subsequently a significant proportion of its capacity got linked to gas based generation. Even then about 50% still continues to be on coal.

Visits to these power plants revealed the significant difference between the quality of coal which is supplied to these plants and the coal which is supplied to power plants in India. It is a fact that most of countries abroad (USA and U.K are just examples) are endowed with good quality coal in terms of calorific value and ash content, though they have the severe most disadvantage of having comparatively higher proportion of sulphur as compared to Indian coal. That is why the power plant personnel in India often complain that their job becomes extremely difficult, almost a challenge, to run their power plants on coal which is supplied to them having ash content in the range of 40 to 50% as compared to 10 to 12% in these countries. It is not only the extent of ash content which is excessively high, which makes their job difficult, but also the nature of processing that is done at coal mines before Indian domestic coal is despatched. Invariably they suffer from unexpected ingredients such as stones and shales which pose difficult situation in their coal handling plants in power stations.

Even in India till seventies, the power plants used to be supplied better quality of coal, though the installed capacity of thermal plants then was very small, approximately 20,000 MW. With substantial expansion of installed capacity, and that too predominantly through coal based plants, a new era in the coal mine development emerged - an era which can be characterized by ever increasing proportion of open cast mining substituting a substantial portion of underground coal mining. While till seventies underground mining produced 75% of total coal and the balance 25% was through open cast mining, in a period of about 30 years this proportion has just reversed - more than 80% based on open cast mining and less than 20% based on underground mining. In a way response of coal industry to an expanding Indian power capacity was adoption of a softer option which very unfortunately brought with it one of the poorest quality of coal produced and supplied anywhere in the world. What is most worrying is the fact that Indian power sector is not content with - nor even the Indian economy is satisfied with - the present trend of power sector growth. Coming years and decades are going to witness an exponential growth in the installed capacity of power generation, much of which will inevitably have to depend upon the coal based generation. It is estimated that Indian domestic coal production will have to be increased from the present level of 400 million tonnes per year to about 2,000 million tonnes in next about 25 years. Coal industry has given to the economy a growth based on its own growth rate of about 5%. It has to grow, at par with power sector growth, at the rate of 9% to 10% per year. The inevitable consequence, it is apprehended, might be again over dependence on open cast mining inspite of the fact that emphasis has been given, in last few years, to increase the proportion of underground mining.

One of the obvious results of the bad quality coal in thermal power plants has been inefficient combustion resulting in higher heat rate . That means , for the same output of power, inefficient consumption of coal leads to higher quantity of coal being burnt leading, in turn, to higher carbondioxide emission. In today's context of global concern about climate change, reduction in carbondioxide emission is the need of the hour. Therefore, clean coal technologies must be encouraged. Countries like India have to work on a twin strategy of (i) using super critical technology in their power plants which are efficient and need less heat to produce same amount of power, and (ii) washing the coal or beneficiating the raw coal by reducing certain amount of ash content and simultaneously processing it in a manner that it is not only properly sized but is free from all the foreign materials.

In India the subject of coal beneficiation has been talked for over last 30 years. But, unfortunately the outcome has been disproportionately lower than what was targeted to be acted upon and achieved. India burns almost 400 million tonnes of coal annually : hardly 80 million tonnes (20%) is beneficiated. Considering the excessively high ash content (40 - 55%) what was required is that by now atleast 50% of 400 million tonnes should have undergone beneficiation before coal is despatched to the power plants. Ministry of Environment & Forest issued a notification in 1998 that all such power plants as are located 1000 KM or more away from the coal mines, should use only beneficiated coal. A proper implementation of this notification would have meant that almost 50 to 60% of coal consumed should have been washed coal. It has not happened and the Ministry has been only extending the date for compliance. The main reason for such a lukewarm approach, and therefore poor consequence, has been on account of an ever existing controversy as to who will bell the cat - whether the power sector will take the initiative or the coal sector would be responsive to the needs of their customers and despatch to them properly graded, screened, processed and washed coal. This controversy has led to, all these years, procrastination and therefore a very slow action and implementation. The net result has been that the power sector has been the loser. If they found that there was some reservation or delay on the part of the coal industry, they should have taken the lead.

Two Coal Washeries for the power sector which came on the scene in the initial years of this initiative are (i) The Washery at Piparwar (Ranchi) for Dadri Power Station of NTPC and (ii) Coal Washery at Deepika Mines (Bilaspur) for BSES Power Plant at Dhanu. I was directly connected with both of these - as GM of Dadri Project during 1985-88 and as Chairman of BSES during 1994-02. Therefore, while articulating about the need for Indian power sector using washed coal in their thermal plants, I could with some degree of intimate understanding justify that apart from environmental requirements, which by themselves should occupy uppermost consideration, it also makes tremendous economic sense to use beneficiated coal. In the case of Dadri Project it is the Coal India Subsidiary, Central Coal Field Ltd. (CCFL) which set up the washery and the cost of washing was included in the price of coal supplied to NTPC. In the case of BSES Power Plant, the washery was set up by BSES itself forming a joint venture with a few other companies. In a way, this was, and continues to be, the first washery in the country to be set up by any power generating utility. The results of both these washeries have been highly satisfying for these power plants. Operational efficiencies have improved, plant outages have reduced and above all the smooth operation has been responsible for a more comfortable working for the power plant personnel. In both these cases quantified analysis have been carried out and it has been established that costs of coal beneficiation have not only been more than offset on account of efficiency of operations, but infact, there have been significant savings to these plants.

An issue has often been often raised whether the economics starts being favourable only for power plants which are located beyond 1000 KM from the concerned coal mines. My own assessment is that it is economical to use beneficiated coal, in the long run, even for power stations which are nearer than 1000 KM, definitely those which are 500 KM or more, and perhaps even those which are at pit head locations.

The issue of coal beneficiation was discussed in the Monthly Vichar Manch organized by India Energy Forum on 26th October, 2007. A detailed presentation was made by Mr. G.C. Mrig, Managing Director of Aryan Coal Beneficiations Pvt. Ltd. and former CMD of Coal India Subsidiary. In the country today about 80 million tones of washed coal is being processed and supplied - about 20 million tones by Coal India Subsidiaries, 25 million tones by Aryan Group and balance about 40 million tones by various other agencies. Salient points of the presentation are outlined below :

  • In view of significant reduction in ash content due to washing of raw coal the land requirement for ash disposal at the power plant location reduces substantially. For example, for a typical 1000 MW power plant if the ash content goes down from 41% to 30% the ash disposal land requirement could reduce from 400 HA to 230 HA.

  • Similarly, water requirement may go down from 17 million cubic meters to less than 10 million cubic meters per year on account of ash percentage going down from 41 to 30%.

  • As mentioned, climate change is a major issue today. As opposed to the general belief that washed coal may not lead to carbondioxide reduction, infact, for the typical case mentioned above, carbondioxide reduction is also of the order of about 3%. This is achieved due to more effective combustion as also less loss of heat in lower quantity of ash.

  • Though the washed coal would improve the power station operations and enhance efficiency, the disposal of coal rejects at the Washery location does pose a problem of their proper disposal.

  • These rejects have a calorific value of 1600 - 1800 KCAL per KG. In the case of Aryan Washery it has been possible to utilize the coal rejects for power generation. They have set up 30 MW power plant based on Fluidized Bed Combustion (FBC) technology.

  • In the end of Tenth Plan (2006 -07) the break-up of distances through which coal is transported to power plants and similar break-up expected in the last year of the Eleventh Plan (2011-12) is given in the following table:

Distance 2006-07 2011-12
Pit head 100 155
Less than 500 KM 55 70
500-1000 KM 43 60
More than 1000 KM 148 216
Total 346 501

These estimates were made at the time of Asian Mining Congress in January, 2006. The figures therefore for 2011-12 might be more because the Working Group on Power for Eleventh Plan submitted its report in January 2007 and Eleventh Plan projections are on a significantly higher scale.

Even though, for the present we exclude pit head power plants and also plants less than 500 KM away, the balance could be almost 300 million tones. All of these by now should have been subjected to beneficiation. We are hardly doing less than one third of what we ought to be doing.

One of the other issues that were discussed relates to the extent of reduction in the ash content. While the washeries developed by Coal India Subsidiaries assure and deliver a reduction from 40-42% to 34%, the washery that BSES developed in 1998, in which I was personally involved, delivers the reduction from 41-42% to 30%. We have often suggested that Coal India may need to revisit the technology, the process and the operational aspects. Conceptually larger the reduction in ash content, lesser could be yield, and correspondingly more of heat could be lost in rejects. In the case of BSES coal washery even though the reduction was of the order of more than 10%, yield of over 80% was achieved. The question is of right balancing and fine tuning the reduction versus yield profile.

Another issue that was discussed relates to further processing of coal rejects through deeper beneficiation rather than using these coal rejects, as at present, to set up power plants based on FBC technology. Both these approaches have relative merits and demerits. It appears that the beneficiation to the extent of bringing down the ash content to about 30% and using the coal rejects for FBC power plants, in the present circumstances might appear to be a viable and therefore desirable strategy to follow. Researches must continue to explore how best any better technology could aim at deeper beneficiation which might reduce ash content to a larger extent, say by 15% or so and yet loose minimum heat in rejects by achieving a higher yield as compared to the yield that is possible today for effecting such reductions.

In conclusion I would suggest the following course of action both for the coal industry and the power industry :

  1. The controversy, whether coal companies would undertake coal beneficiation or the power utilities, must end - infact in many cases it has already ended by power utilities taking the initiative. More and more power generating companies either directly or in joint venture or on the basis of agreement with other companies should ensure that they get washed coal for their plants.

  2. To start with all such plants as are 500 KM or more away from their concerned coal mines should target getting washed coal in next two years. This target is possible to be achieved.

  3. Coal Ministry and Coal Companies have been giving the necessary support but the process needs to be institutionalized and notified so that power generating companies and their coal washing agencies get encouraged to prepare and meet the above targets. The facilitations which are required include making land available both for plant and for coal rejects, water availability and siding infrastructure. In the overall interest of environment, these inputs should be provided.

  4. Coal India Subsidiaries themselves also should fix their own targets to set up washeries wherever the generating companies are not taking such initiatives.

  5. Invariably coal rejects could be used for FBC power plants. Here again necessary inputs may have to be provided by the coal companies and by the concerned State Governments. A proactive and supportive response of State Regulatory Commission on this subject will be necessary and will be a great help.

  6. In the subsequent phase, power plants located at distances less than 500 KM from coal mines could also consider similar approach. I genuinely believe that both economics and environment put together will justify washed coal even for these power plants.

  7. Pit head power plants of NTPC and other generating companies should carryout analytical exercises whether for the existing plants washing of coal could be justified on the basis of economics and environmental considerations. These are border line cases. But my own assessment is that they would get justified.

  8. In any case, future pit head power plants as also other plants, must plan processing of coal in the concerned mines including washing, reduce capital costs in power plants on the concerned systems namely Coal handling, Ash handling, Mills and Electrostatic Precipitators as well as connected systems of water supply and electricity consumption etc. For new plants, this approach, I have absolutely no doubt, will justify the economics of beneficiated coal even for pit head power stations.

  9. After allowing two to three years for a voluntary compliance and action on these lines, regulatory instrument should be made effective for enforcement through judicious application of grant (or non-grant) of consent to operate the power plant.

  10. Ministry of Environment and Ministry of Power together could consider to institutionalize a mechanism which could facilitate the process of setting up of coal washeries by power generating companies or their contracted agencies. This would be necessary because there are a number of inputs and clearances which are required to be obtained from Central Government, State Government and Coal Companies.

Copyright : R.V. SHAHI