The cement industry in India has been steady on the path of sustainable growth, after it became a "free commodity" in 1989. The industry made phenomenal progress in terms of production volume, technology and product upgradation. The challenge now is to continue this growth in a sustainable manner. Dr J D Bapat has a few insights to share on this.
India today boasts of modern state-of-the-art large capacity cement plants, and the quality of Indian cement is at par with the best produced anywhere in the world. Moreover, India is expected to overtake developed countries like USA, UK and Canada in terms of per capita cement consumption by 2025.
In the Indian cement sector, there are 70 companies with 183 large and 360 mini cement plants; the majority (94 per cent) of the production comes from the large cement plants. The cement sector shares 1.3 per cent of the national GDP and employs about 140,000 persons. In terms of production capacity, at present, the Indian cement industry is positioned at second rank, globally. The cement production units are located near the limestone reserves, for the requirement of consistent supply of raw materials and the economy. Hence, clusters of cement plants are built near the limestone reserves; 13 such clusters account for nearly 75 per cent of the capacity. The production units away from limestone reserves are established on the split-grinding concept. Since cement is a high-bulk-low-value commodity, the competition is localised, as the cost of transportation to longer distances often makes the product uncompetitive in distant markets. The cement consumption is linked to the cycles of economy and the climate, reaching its annual peak in the month of March and bottom in the months of August-September.
Growing energy demand The energy consumption per unit mass of production, both thermal and electrical, has been brought down considerably through modernisation and productivity enhancement efforts. The thermal and electrical energy consumption achieved in the modern Indian cement plant is comparable with the best obtained globally. The decomposition of the raw material, limestone, creates most (about 60 per cent) of the cement industry's direct CO2 emissions; the rest comes from coal burning and power generation. Whereas the cement installed capacity has increased from 168x106 t/a in 2006 to nearly 350x106 t/a in 2013, the CO2 emissions have also increased correspondingly though the rate of increase is lower.
Reduced emissions In fact, a study conducted by the World Business Council for Sustainable Development (WBCSD) indicates that the net CO2 emissions per tonne of cementitious, globally, have reduced by 17 per cent. This has been achieved mainly by partial substitution of clinker with the Pozzolanic and cementitious materials, such as fly ash and blast furnace slag. The proportion of blended cement produced the country is currently about 67 per cent and is likely to touch 80 per cent of the total, in the coming years. It could be said that the cement industry in India has achieved a significant partial decoupling of economic growth, represented by the cement production and absolute CO2 emissions.
Some Indian cement majors have signed a co-operation pact to support low-carbon investments in India. The pact was signed in Geneva with the member companies of WBCSD Cement Sustainability Initiative and International Finance Corporation (IFC). There are some negative factors that need to be tackled, some through technology upgradation and some through improved policy framework.
The electricity supply is unreliable in many areas of the country, hence cement producers have installed their own captive power plants with high efficiency boilers and, more recently, waste heat recovery installations. Although the specific power consumption has been substantially reduced through modernization and productivity enhancement measures, there are certain barriers to bring it down further, namely high investment costs required for major retrofits, stringent emission limits require more power for dust separation and demand for high performance requires substantially high grinding energy for fine grinding of cement.
Alternative fuel The fuel used in cement manufacture is mineral coal. In view of the poor railway transport linkage and the low quality and high cost of coal in the open market, many cement companies import coal, which is expensive. The alternate fuels in the kiln reduce dependence on coal. Some plants have substituted mineral coal with petcoke (solid carbonaceous residue produced by thermal decomposition of heavy petroleum fractions or cracked stocks, or both), partially or fully, for kiln burning. The alternative fuels currently used by the cement industry include domestic and industrial wastes (mainly solid).
The cement kiln is particularly well-suited for such fuels for good reasons: the organic constituents (even toxic) are completely destroyed due to high temperature, long residence time and oxidising condition in the kiln, the acidic gases get neutralised coming in contact with alkaline materials in the kiln, the energy component substitutes for fossil fuels and the inorganic components i.e., ashes, get integrated into the clinker product. These are effective substitutes with lower CO2 emissions than traditional solid fuels. The typical alternative fuels used by the cement industry are pre-treated industrial and municipal solid wastes (domestic waste), discarded tires, waste oil and solvents, plastics, textiles and paper residues, biomass: animal meal, logs, wood chips and residues, recycled wood and paper, agricultural residues like rice husk, sawdust, sewage sludge, biomass crops. These wastes may otherwise be burnt in incinerators, land filled or improperly destroyed. The substitution of alternate fuels for cement production is about 10 per cent, globally; in India it is much less. In some European countries, the average substitution rate is over 50 per cent for the cement industry.
Cement capacities The report prepared by the Tariff Commission, Government of India, indicates reduction in the cement capacity utilisation from 93per cent in 2006-07 to 74 per cent in 2010-11, and the situation has not much changed since then. However the requirement of the installed capacity to the tune of 1035x106 t by 2027, almost three times the current installed capacity, has also been projected. The cement demand will be mainly driven by the infrastructure and housing sectors, in the coming years. More than improving the capacity utilisation, it is likely to create problem in the availability of limestone reserves. The forecast says, with the current level of capacity utilisation, the limestone reserves may last for only the next 35-41 years. That is an area of concern.
The following measures may be considered, if the march of Indian cement industry towards sustainable growth is to be continued.
Petcoke burning: Besides the cost savings, the use of petcoke enables use of low or marginal grade limestone as raw material. This single factor leads to the extension of mine life, natural resource conservation and reduction in CO2 emissions.
Alternate fuels: Technically, it is possible to increase the substitution rate of alternate fuels for the kiln. Some Indian cement majors have already taken an initiative in that direction. The United Nations Environment Programme's (UNEP) Basel Convention (March 1989) discussed and devised the "Technical guidelines on the environmentally sound co-processing of hazardous wastes in cement kilns." These guidelines were adopted by the tenth meeting of the Conference of the Parties to the Basel Convention, in October 2011; India has ratified these guidelines. An appropriate amendment to the Hazardous Waste Management (HWM) Rules is required so that pre- and co-processing can be efficiently undertaken by the cement industry, in gainfully utilising the wastes.
Limestone utilisation: Ensure gainful utilisation of low and marginal grade limestone through application of appropriate technology.
Blended cement: The application of blended cement improves strength and durability of concrete. The use of Portland Pozzolana Cement (PPC) and Portland slag cement (PSC) should be encouraged in all public works. It appears, some government departments still have reservations about the use blended cement or the application of mineral admixtures in concrete, which could be sorted out through discussion. The relevant Indian Standard Specifications should be modified, in line with ASTM C5952, to allow greater utilisation of mineral admixtures in cement and concrete. The high volume fly ash concrete (HVFAC) and blending of limestone powder with cement are some examples. Huge quantity of ash is dumped in lagoons near the thermal power stations. Efforts are required to use it in construction, without or with processing. Rice husk ash (RHA) is a promising mineral admixture, for Indian conditions. The government may consider starting a 'RHA Mission'for its proper utilisation.
Infrastructure and manpower: The growth in cement production will lead to an increase in the demand of various resources required for producing and distributing cement. The transport infrastructure and availability of skilled manpower may become major bottlenecks, unless proactive steps are taken.
Dr JD BAPAT
Indian Standard Specifications should be modified, in line with ASTM C5952 to allow greater utilisation of mineral admixtures in cement.