The regulatory authorities of late, have also been stipulating stringent conditions for coal-based power plants keeping pace with the technological advancement followed by the serious threat of global warming. The combination of the need to improve the efficiency and stringent regulatory norms leave no option for coal based power generation but to transform for better soon.

An attempt has been made to outline the greater advantages of efficiency improvement in the coal based power generation and also to look at the potential benefits of the renewable energy.

ENVIRONMENTAL ISSUES OF THERMAL POWER PLANTS

The initial exercise on guidelines for thermal power plants in India has assumed greater significance of late, in addressing critical issues related to the primary resources of land, air and water consequently leading to a serious introspection on technical option for coal based generation.

When we look at some of the examples under land, air and water, it is evident that the environmental issues are likely to govern the future trends in coal based power generation. The land requirement for just the ash disposal indeed has been an outstanding example in this regard in the light of 100% ash utilization over a period of nine years leaving scope to explore the alternative approaches sooner or later but, surely quickly. Ash water recirculation, appropriate measures to contain the potential threat to ground water contamination and preventing excavation of good earth for dyke construction are a few more which, complicate the ash pond related issues in the coal based power generation.

Emission standards for sulphur dioxide which has been long over due, mercury containment, ground level ozone and carbon dioxide reduction on similar lines, are a few other aspects which are under serious consideration by the Ministry of Environment and Forests (MoEF). Water conservation is equally at the top of the agenda while according environmental clearance for the power projects.

Although it is not binding, India signed Untied Nations Framework Convention on Climate Change (UNFCCC) as non-Annex I country sending clear indications on its commitment to reduce carbon dioxide and other Green House Gases (GHGs). India accepted the Kyoto Protocol in August, 2002.

MoEF responsible for the guidelines and standards for a variety of industries including thermal power plants (coal and gas) have already initiated the process through stringent conditions to keep pace with the overall development in the power sector.

POWER SCENARIO

The Indian power sector has in fact, grown from a meager 1713 MW in 1950 to 1,23,900 MW as on January, 2006 out of which 68,433 MW is through coal; 12,663 MW gas and 1200 MW by diesel. While the thermal contribution stands at 66%, coal alone accounts for almost 55% of this capacity.

Out of projected 160 GW power addition by 2020, 60 – 80 GW would be shared by coal based generation. The primary resource estimate on this account would be crucial in the light of the current land use pattern – India’s total cultivable area is 1,269,219 Sq. Km. i.e. 56.78% of the total land area.

There has been a steady progress in the Plant Load Factor (PLF) as well from 27% during the first plan to almost 75%. There have been exceptional units performing at almost 100 + PLF as well. The Electricity (Supply) Act 1948 was amended in 1991 to facilitate participation of private generating companies.

Coal based power plants consequently need to adopt technologies to reduce coal consumption and or improve efficiency in view of its major share in power generation in the country.

MODEL APPROACH

Natural gas, nuclear and renewable are a few pointers under fuel switch with each one of them possessing positive and negative scores for consideration. However, efficiency improvement and carbon dioxide sequestration and capture would be inevitable considering the overall technological development and environmental priorities.

Power plants operating in a variety of geographical boundaries have presented enough scope for the ancillary development around them often presenting an undesirable growth around. It is this boom town and haphazard development that fails to merge well with some of the well maintained power plants in the country. In fact, it presents a contrasting scenario moving towards the exciting & pleasant aesthetics of the power plant premises.

Further, it is evident that 70% of populations who still live in rural areas are either directly or indirectly influenced by the power plant establishment. The power plants established at the sacrifice of the rural folks residing in the area over a long period have, been fulfilling their social obligation through the National Policy on Rehabilitation & Resettlement (R & R). However, the social commitment in exceptional cases exceeds the ambit of R & R. Corporate Social Responsibility (CSR) which has evolved over a decade now is a new dimensions catching up with a number of large Corporate Institutions, in the country today. The Government of late, has also provided a good opportunity for village electrification under Decentralized Distributed Generation (DDG) scheme through renewable energy technologies.

There are indeed a variety of options for coal based power plants to address efficiency & carbon dioxide reduction issues simultaneously, imbibing the renewable options as well. The ideal approach of combining the business interest and achieve a better Corporate Image is indeed through looking beyond the mandatory requirements of sustainable development. The social values that are likely to be created through such initiatives would gradually merge with the Corporate Objectives as an integral component. The following outline provides innumerable options for the power plant in achieving this objective.

The best way to achieve this goal is perhaps, to adopt the villages around one to two kilometers of the power plant for demonstrating renewable energy options to uplift them. In the light of this background, it is ideal to extend the scope of Decentralized Distributed Generation (DDG) for village electrification based on renewable energy technologies such as Biomass gasifier, Solar Photovoltaic & Bio-diesel.

The power plant could be the pride owners of such demonstration sites and the transition zone (1-2 Km around the power plant) with these workable renewable options not only present a pleasant look around the power plant but also, would be sites of learning for the surrounding villages to emulate.

. Although a number of potential options are available for the power plants, the primary focus has been on Efficiency improvement. The illustrative example outlined below provides not only a solution towards this goal but, throws open a number of other possibilities as well as can be seen from Figure 2.

Since ash pond related issues have been highlighted in the beginning of this paper, abandoned ash pond would be the ideal sites to reap the benefits outlined above. The efficient utilization of abandoned ash pond site coupled with the renewable options for rural electrification fulfils the objectives outlined earlier.

Thermal generation particularly, coal based at 55% (68433 MW) of the present installed capacity would have consumed 68433 acres of land for just the ash disposal at 1 acre per MW. Additional land would be warranted for the projected coal based generation by 2020. It may therefore be seen that the precious land is locked up for dumping this inert material – ash – over the next 20 – 25 years or life of the power plant.

Ash pond reclamation has been quite a challenging task considering the physical properties of ash. However, there are now, innumerable examples of successful reclamation through a variety of plant species, world over. It is the extension of this ash pond reclamation that has been outlined for the abandoned ash pond sites, of power plant.

Fly ash, a derivative of coal poses serious environmental problems not only in India, but elsewhere in the world as well. The problem assumes astonishingly greater dimension in India owing to the deployment of the worst coal (unfit for any other use) in the power industry with ash content between 35 and 50%. Ash is disposed off conventionally as slurry to ash disposal area – “Wet Disposal System” resulting in what is generally referred to as “Ash Pond“.

The initial hurdles of growing vegetation over fly ash were overcome owing to new outlook of treating them as a "special kind of soil" which led to the analysis of ash. The physico-analysis of ash warrants selection of best-suited species for trials and reclamation of ash ponds.

The most popular Bio-diesel* species in India (Jatropha curcas – Ratanjot; Pongamia glabra – Karanj) can very well be cultivated over either abandoned ash ponds or low lying areas filled with fly ash. Cultivation of such species not only account for the reclamation of ash surface presenting a number of environmental benefits but also provides an additional product - bio-diesel - for use within the project or in the surrounding villages.

( *The trans-esterification process involves mixing at room temperature methanol (50% excess) with NaOH (100% excess), then mixing vigorously with vegetable oil and letting the glycerin settle (about 15% of the biodiesel mix). The supernatant is biodiesel and contains a mixture of methylated fatty acids and methanol, the catalyst remaining dissolved in the glycerol fraction. Industrially, the esters are sent to the clean-up or purification process, which consists of water washing, vacuum drying, and filtration.)

Bio-diesel produced from such sites could find its way either:

• Directly as a product to the surrounding villages where huge amount of diesel is being consumed for several activities, mainly agricultural;
• Or indirectly through clean power generation through smaller power units on bio-diesel.

AND

• Organised Biomass Collection would be useful in gasification
• The plantings would sequester Carbon Dioxide
• The de-oiled cake would serve as a good fertiliser.

Considering the current land under ash disposal, reclamation of even 10% of such sites would be extremely beneficial. Reclamation with bio-diesel species would facilitate 3 – 4 times return independently as per the available estimates. The returns could further be attractive through select commercial species as intercrop on the same site.

Looking at the characteristics of bio-diesel and a calorific value of around 10,000 kCal, it is believed that the bio-diesel spray on coal would enhance the calorific value from the existing 3000-4000 k/Cal.. The enhanced calorific value of coal will have a significant influence on not only the quantum of coal burnt but also on the emissions as well, consequently. This reduction in coal will eventually result in reduced particulate / gaseous emissions.

Power plants could therefore lead the way by adopting these bio-diesel species and demonstrating their use for emulation at other thermal power stations.

Conclusion

Although the above outline is one of the options, a number of other aspects would benefit coal based thermal power plants in improved efficiency. Taking cue from the best operated power plants, the aspects such as resource optimization (water, steam for example), preventive maintenance, predictive maintenance IF, adopted at the coal based power generation, they would greatly enhance the performance of the existing power plants and contribute in saving otherwise wasted power.

There are reports on zero emissions, water free power plants and wireless transmission, which hopefully would be available for implementation at power plants sooner or later.

Note: Views expressed in the paper are of the Author only

To join in on the conversation or to subscribe or visit this site go to:  http://www.energypulse.net

Copyright 2005 CyberTech, Inc.