Cement Energy and Environment

~ste To Wealth & Waste L Recycling ACC TO SUBSTITUTE 5% COAL NEED WITH WASTE The country's largest cement-maker ACC has embarked upon an ambitious project for substituting 5% of its annual coal requirement of about five million tonnes over the next three years with waste generated by cities and indus– tries. Global cement major Holcim controlled ACC, which saved Rs.47 crore last year on fossil fuels, aims to save Rs.60 crore in 2011 by burning waste , primarily plastics, at its plants. Courtesy: The Hindustan Times, October 3, 2011 ENERGY RECOVERY FROM MUNICIPAL SOLID WASTE FOR CLEANER HABITAT With its growing population and improved standards, urban India generates 42 million tonnes of municipal solid waste (MSW) annually, 75 per cent of which is either landfilled or openly dumped. With such prevailing practices, land with disposed MSW will soon start encroaching human habitats. Urban settlements, in particular, with large population face this challenge which necessitates efficient MSW handling and management techniques that maximize recycling and energy recovery. MSW generated in India is predominantly organic in nature which has a total potential of generating 1700 MW power out of which only 17 MW has been so far installed in cities like Hyderabad, Lucknow, Vijaywada, Ludhiana, Surat and Chennai. Recent advances in scientific research have established the application of thermo-chemical (incineration, gasification and pyrolysis) and biochemical (anaerobic digestion and bio-methanation) procedure of converting waste to energy. The 6 MW power plant in Hyderabad uses 210 tonnes of refuse derived fuel (RDF) processed from 700 tonnes of MSW each day and has produced over 48 million units of electricity since 2003. A similar venture in Vijayawada uses 150 tonnes of RDF per day from 600 tonnes of MSW per day. In another private venture in Lucknow, a 5 MW plant is operational that uses 50,000 cu .m biogas from MSW and generates organic fertilizer as a by-product. Other small scale projects are also operational which are specific to the waste types that include market waste, slaughter house wastes and mixed waste. With the given scale of energy demand and the amassing MSW within and outside localities, there is huge potential to generate energy as well as dispose MSW off. Although the significance of electricity is undisputed, modern techniques can be used to provide a range of products that will cater to the needs of a community depending on its technological maturity. In this regard, pyrolysis appears to be significant in Indian energy scenario as it produces all three usable forms of energy char (solid), producer gas (gaseous) and bio– oil (liquid). Pyrolytic studies on MSW have resulted in healthy product distribution comprising of high quality char (32 - 49 per cent), producer gas (18 - 20 per cent) and bio-oil (30 - 50 per cent), which can be potentially, used directly or indirectly, for household and/or community purposes. For instance, small size urban centers with population of 1 mi!Hon will produce 270 TPD of waste (0.27kg/personlday). Considering a futuristic value of 60 per cent organic fraction in MSW (World Bank .1999), 162 TPD will be available for energy recovery. Complete utilization of that organic fraction in pyrolysis will produced 51 - 80 tonnes of charcoal, 30 - 32 tonnes of producer gas and nearly 48 tonnes of bio-oil. In addition, basic technical customizations will lead to maximization of a particular product. As a result, the community gets to determine and produce its own fuel requirement as per the regional technological maturity. For example, charcoal production can be maximized in areas with predominant use of charcoal. Similarly, communities willing to upgrade to gas stoves can maximize produce gas output through temperature adjustments. Therefore, it can be easily imagined that on implementation of such projects in decentralized pattern, local centers of sustainable development will be created based on the amount of waste material effectively collected and pyrolysed. Private participation will further enhance the effectiveness of the project via objective planning and diligent monitoring. Disposing and effective handling of waste can have numerous positive impacts on resident population by eliminating disease vectors and creation of a pollution free habitat. People living in slums are more subjected to polluted and unhygienic localities where MSW handling and disposal practices are irregular. Efforts 28 • I