The construction sector in India is responsible for a large share of the CO2 emission into the atmosphere. This is due to large scale of construction activity, and increasing use of energy intensive materials like cement, steel and bricks. The energy consumption patterns and resultant emissions from production of these materials are assessed with a view to identifying how the total emissions could be stabilized without limiting supply. The inevitable growth of population and scoietal expectations over the next few decades will require a significant augmentation of supply. To minimize the net CO2 emission the only viable solution clearly lies in developing a sustainable building production system based on alternative low energy building materials and more energy efficient technologies. The net energy saving possible from a series of actions involving technology improvement and partial material substitution in walling, has an energy saving potential of 33% compared to a technology –as-usual scenario, based on existing technology. A further 50% energy reduction is possible through the use of industrial wastes in combination with line. While the study has on one hand focused on technology issues – options and factors that influence technology change and substitution, it also simultaneously identifies measures at the policy level needed to trigger these technology changes. Finally, the study has identified structural transformation processes required over different time horizons to activate the judicious use of resources leading to a sustainable building economy and stabilization of emissions. The abridged study is being published in two installments. The study was commissioned by the Swiss Development Co-operation and INFASIAIE. IntroductionEnergy is the key to industrial development leading to economic growth for the provision of essential services that improve the human condition. Although there is no evidence that the world has begun a transition away from dependence on fossil fuels, there is growing concern that their accelerated use may lead to increased emissions of greenhouse gases causing unprecedented greenhouse warming and climate change. India’s per capital emissions of carbon dioxide (CO2 ) is small (0.22 tc/ yr) at present in comparison to the world average (1.17tc/yr). India’s population which is at present about 844 million, with a population growth rate of 2 percent a year may reach a billion by the turn of the century. With the liberalisation of India’s economy, it is likely that pace of India’s development may considerably increase the total CO2 emissions from different economic activities in future, though the per capita emission of CO2 in India may not be very much different than at present. Economic growth needs to be achieved through a process of sustainable development that does not put pressure on resources nor adversely impact the ecology and environment. The construction sector is the highest contributor constituting 22% of the total CO2 emissions resulting from the Indian economy.
Development Alternatives has conducted a study of energy demand and CO2 emissions from the construction sector in India and the technological interventions that are feasible to reduce energy demand and emissions from the same. Imperatives of Current Building ScenarioThe construction sector uses various energy intensive materials such as steel, aluminum, glass, cement, lime and bricks. The energy usage for the construction sector is a major factor contributing to the CO2 emissions. For each of the four building materials, cement, steel, brick and lime, there exists a technology spread within each sector characterised by widely varying levels of energy and material consumption. The energy and emission computation have been derived for the four materials as a function of technology as well as the scale of production. The total energy and emission for the year 1989 - 90 for the four building materials have compiled in Table 1. All CO2 emissions are indicated as tonnes of carbon (tC) also. The increasing demand for building materialsing the construction sector is a direct outcome of galloping demand for housing . Of the total material output 60% of the construction sector is allocated for domestic housing purposes. The past trends indicate a clear shift towards more permanent (pucca) materials like bricks and cement. The projections in this study are based on a continuing growth trend of 2.4% per annum cumulative growth rate obtained from the Census report 1991. The Government of India VIII plan document states that 21.77 million units are likely to be added in the plan period 1992-97. The housing gap – currently 30.8 million houses, will be closed by the year 2011 and by the year 2020, housing will finally be provided to the estimated population of 1308 million (based on low population growth scenario). Although it appears that the percent growth rates are slowing down, the fact remains that about 3.9 million houses need to be added annually in the period 2001 – 2021. This is indeed a challenging and formidable task. Figure (1) indicates consumption of Cement, Steel, Bricks, Lime in the construction sector from 1981-93 which sets the reference for future projections. Galloping Demand : Projections for Building MaterialsThe demand projections for housing have been derived on the basis of the existing housing stock, the housing shortage and with the intention of closing the housing gap. Development Alternatives study has assumed that 41 million households are to be provided in the decade 1991 – 2000 as per the VIII plan projections. For the subsequent two decades also (2001 – 2020) a stable rate of 4.1 million houses per annum has been assumed. While working out the probable demand for cement, steel, bricks and lime, the growth rates of different sectors in the Indian economy which involve construction activities, have been taken into consideration. The projection is shown at Fig. 2. On the basis of the most probable demand for building materials, the energy and emissions have been computed according to the technology mix prevalent in 1989 – 90. Development Alternatives (DA) Demand Projection In the case of the DA’s demand projections, the growth rate of different building industry sectors of the Indian economy have been analysed to assess future demand. These demand projections are based on :
Specific assumptions for each of the four materials are enumerated below : Cement The Development Council’s forecast up to 1997 has been extrapolated assuming 5% growth rate synonymous to the GDP growth rate over the 1980’s. SteelThe Centre for Industrial Research has projected a growth rate for steel up to 2005. Demand for construction steel is derived from this and amount s to 80% of non-flats, including railways and 5% of flats. Beyond 2005, up to 2020 a growth rate of 5% has been assumed although there is likely to be an accelerated growth of 6-8%, specifically with respect to roofing applications. Bricks The demand for bricks has been made on the assumption that the construction sector comprises 60% housing needs and 40% non-housing needs. The growth rate for housing is assumed to be the same as for the decade 1981 – 91, which is in congruence with the Government of India’s VIII plan projections during this plan period, 1992 – 97. The nature of building materials used in housing has been taken to 75% permanent as per trends up to 1991. Beyond 2001, the growth rate has been revised downwards to conform to the population growth rate. The housing gap is likely to be closed by 2011 if the projected trend persists. Lime The Mineral Year Book has published data up to 1989 on the supply of limestone to the building lime industry. This has been used to calculate future projections. A growth rate of 7% , similar to that of cement has been assumed up to 1997, beyond which the 5% growth rate ascribed to the GDP has been used. The method for assessing growth takes into account present trends of material consumption achievable at the prevalent mix of technologies within each sector. The assessment as already stated, in most cases forms the lower bound projection as it does not take into account the augmentation of supply possible due to improvements in technology. In any case the demand is projected within the ceiling of growth of 5% of that existing in the several sectors feeding into the Indian economy. The summary of the specific energy and emissions for the four materials derived through the DA study has been presented. The energy and emissions up to 2020 have then been computed using specific energy consumption and carbon emission factor. Although steel and cement together constitute more than two – thirds of the net contribution, these are sectors that are showing positive signs of adopting energy efficiency measures. Bricks, having a share of 15-16% in energy use, continues to be a neglected industry which is specially alarming, considering that the present trend of the economy is a clear pointer to increased housing and therefore increased demand for bricks. Assessment of Impact of Technology TrendsIt is evident that with the escalating demand of building materials projected in the probable scenario, the present mix of technologies will result in a three fold increase in the energy consumption and resulting emissions in the next three decades 1990 – 2020. The contributions to the emissions are projected to increase from 81 million tonnes of CO2 to 285 million tonnes. For the construction sector this scenario is equivalent to 4.3% increase per annum and in terms of per capita contribution, a doubling of emissions. Clearly such a trend is not sustainable as it signifies the ‘worst case' scenario for emissions. In the discussion that follows the energy and emission reductions have been quantified in relation to the technology improvement s that are achievable for the respective materials; cement, steel, brick and lime. Two progressive cases of emerging technologies have been evaluated, allowing for augmentation of supply to match the likely demand for each of the four materials. These are presented alongside “Technology as Usual”. The three cases are :
Cement There are three distinct types of cement manufacturing processes prevalent in India, namely dry, semi-dry and wet. Plants based on the wet process were established during 1950-65, and found favour due to requirement of low-grade fuels. Semi-dry process is the most common retrofit measure in instances where upgradation of technology has taken place. Dry process is the most modern and energy efficient process and has been identified as the “Best Practice" available in India today with 70% of the production using this process. The Gujarat Ambuja plant at kodinar in Gujarat is the industry front runner reporting a specific power consumption of 91kWh/tonne cement against the industry average of 117 kWh/tonne. The energy reduction potential in the cement industry in comparison to the present mix of technologies is 0.45 GJ/tonne. This is achievable through upgradation of the outdated processes to the dry process. The large scale plants are set up in the vicinity of large limestone deposits, often entailing large scale transportation of coal and finished products. This could account to as much as 11% of the net cost of production. Precisely for this reason, further reduction in indirect energy is possible through a concurrent strategy for promotion of mini cement plants. Technological interventions has significant impact on reducing the energy consumption and emissions. Steel The majority of the Integrated Steel plants (ISP) in India use the Blast furnace route for production of molten iron. This is processed through the Open Hearth route (OH), for steel making. Since the 70’s the Linz Donowitz (LD) process has been used to supplement the capacity of steel making. Most plants continue to operate OH furnaces and LD converters. An ISP starts with iron-ore, coke, limestone and power as inputs and makes iron, steel, castings, hot and cold rolled products and other heavy structural products. This sector accounts for over 90% of the steel production. Mini steel plants using Electric Arc Furnace (EAF) account for only 25% of the installed capacity, which is grossly under utilized. The mini steel uses sponge iron and scrap iron and electricity as inputs producing slabs, flats and non-flats. As per industry forecasts one can expect that there will be any significant enhancement in capacity of large Integrated steel plants. All additional capacity will be met by mini steel plants and Non Integrated Steel Plants. With the limited availability of indigenous scrap, the Electric Furnace Units (EFUs) will rely on Direct Reduction Iron and Hot Briquetted Iron as raw materials. Modern mini steel plants using automation and energy saving devices are today capable of producing 15,000 to 2,000,00 tonnes of product per annum. The increasing contribution of the mini steel plants is inevitable due to the fact that 15-16% of the new demand for steel will be met by this sector and the fact that production from these units finds its way almost exclusively into the construction sector. This segment therefore needs boosting. The Best Practice in mini steel production, based on material availability, is the use of 30% spone iron blended with scrap. This process has the distinct advantage that it uses non-coking coal for direct reduction. Further improvement through new technology is possible through the use of natural gas for sponge iron production. This reduces the CO2 emission levels by 30% (refer Annexure I : Section 1.3.4). The large sector has numerous possibilities of achieving at least 30% reduction in energy consumption through a series of technologies like thin slab continuous casting, coal injection and through the Corex process which also eliminates the use of coking coal. The technological interventions on the steel production has significant impact on energy consumption and emissions. Brick The specific energy consumption for bricks is low but the large demand entails fuel consumption equivalent to over ten million tonnes of coal per annum. The most commonly practised technology is the Bull’s Trench kiln with an average capacity of 20,000 bricks per day. The variation in fuel consumption is from 5.1 GJ/1000 to 3.2 GJ/1000, in different parts of the country depending on type of chimney, fuel type, soil type and firing practices. The introduction of the fixed chimney kiln is one major technology leap whoch occurred almost three decades ago. The disheartening factor is that only 10% of the kilns countrywide have adopted this technology variant even though the fuel savings are well established. The Central Building Research Institute, Roorkee, has developed a High Draught Kiln which is a top-fed, forced draught kiln, with a capacity of 25,000 bricks per day. This kiln has been technically demonstrated to be an extremely fuel efficient technology. The emissions are greatly reduced due to proper combustion achieved by the use of pulverised fuel and assisted draught. However, a capital cost of Rs. 300,000 with additional requirements of power, result in a payback period in excess of five years. As a result the small-medium entrepreneurs have refused to adopt this technology widely. The Vertical Shaft Brick Kiln, prevalent in the small scale sector in China, appears to be an attractive technology. With a fuel efficiency equivalent to the CBRI kiln, this technology consists of a vertical firing shaft in which the bricks are top loaded along with coal fines, and unloaded from the bottom. The capacity of each shaft is about 8000 bricks/day, with two shafts being equivalent to single Bull’s trench kiln. Energy efficiency is achieved by utilizing the waste heat for drying and prefiring the green bricks. The impact of technological intervention on energy and emission levels is summarized. Lime Building lime is an almost extinct industry today even though the relevance of lime in the building industry is still crucial. Presently building lime sold in the market is highly adulterated consisting of rejects from plants geared to meet the demand for lime is low. The most common type of kiln in India is the Vertical Shift Brick Kiln (VSBK). Improved kiln designs have been put forth by Khadi Village Industries commission (KVIC). The raw material limestone is mixed with the fuel coal and fed from the top, and lime is discharged at the bottom. These are tall cylindrical kilns with varying length to diameter ratios. They are refractory lined and have discharging doors at the bottom, which also supply air for pre-heating. These kilns are favoured due to low capital and operating costs, simplicity of construction and good thermal efficiency. The importance of lime is to encourage decentralized and dispersed material production centers. Lime can also be linked to the utilisation of industrial wastes thereby leading to building material production centers near industries generating wastes, to meet local demand. Lime production can be promoted in areas where surface deposits of limestone are found as in some places in Rajasthan which could lead to a partial replacement of cement with lime in plasters and mortars. The investment requirement for limestone production is as small as Rs. 200/tonne of lime with favorable capital : employment ratio. The technology can be easily upgraded for small scale manufacture through institutions promoting mini cement plants. The net impact of technological interventions is shown.
Growth and Demand for the Four Major Building Materials : A Summary These technology options are superimposed on the projected demand scenario for building materials given in Figure 2. Three distinct scenarios have been developed to understand the impact of wide adoption of these technology options on net energy demand and resultant emissions.
In a situation where the projected demand for materials is expected to grow exponentially, the cumulative energy requirement for 4 materials is expected to increase for 742 PJ to 2363 PJ under Technology-as-Usual scenario. The introduction of Best Practice has a net positive impact in reducing the energy consumption by 17% to 2000 PJ for the year 2020. On the basis that all new installed capacity conforms to the new technology available, the total energy saving possible is 563PJ equivalent to 25% of the total energy consumed through present technologies. Similarly, the impact of introduction of best practice coupled with new technology for additional capacity created is a net reduction of 25% in emission levels. These changes reflect the energy savings possible through technology intervention alone with projected demand for building materials being fully met. In reality, the future production will be governed by availability of resources. The first outcome of restricted resource availability is projected to be a saturation of supply of bricks. In evolving a strategy for developing sustainable production systems with a saturating supply of burnt bricks, the study has determined an option which incorporates the use of concrete blocks to supplement the supply of walling materials. It becomes imperative to examine the effects of material substitution which when superimposed on Best Practice and New technology, can further reduce the energy requirements and the resultant emissions. |
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