Augmentation of Supply: Assessing Technology Alternatives Scenarios for Walling – Focus Bricks The demand projection for burnt bricks has been made on the basis of housing demand and trends towards pucca construction. The most probable scenario for housing has been evaluated for closing the housing gap. On the basis of a projected demand of 45.31 billion bricks in 1990, the projected demand for 2020 is 89.1 billion bricks. According to the projections of the Planning Commission for the VIII plan period later verified by Building Material and Technology Promotion Council, the brick production is likely to saturate at about 46.5 billion per annum (Fig. 4). This is attributed to the limited availability of clay of requisite quality coupled with restricted availability of fuel and increasing environmental concerns regarding operational of existing brick kilns. The opportunity to evolve a strategy for reduction of emissions can thus only be seen in the context of fulfilling demand through augmentation of supply. The current energy demand for 45.31 billion bricks is estimated to be 190 million PJ equivalent to 10 million tonnes of coal. If the production of burnt bricks is allowed to grow unabatedly to meet the projected demand of housing, this would lead to a doubling of the energy requirement by 2020 equivalent to 19.9 million tonnes of coal. The resultant CO2 emissions would also double during the period 1990 to 2020. The particular case of burnt bricks, exemplified by above figures, is indeed very significant in the economy as it accounts for 27% of the energy consumption for construction materials. The existing brick industry is already under notice from the Central Pollution Control Board to limit the emissions and environmental pollution by adopting improved technology. According to the Development Alternatives study, the technology shift in the brick industry can be engineered effectively due to favourable conditions resulting from environmental pressures as well as assured demand. Energy Efficiency through Best-Practice Technology The current best practice technology available is Fixed Chimney: Bulls Trench, and is restricted to about 10% of the 60,000 brick kilns functioning in the country. The common practice Movable Chimney: Bulls Trench accounts for the majority of the balance production. A shift to best practice technology is now possible on a wide scale due to requirements posed by environmental regulations. For he projected demand of 89.1 billion bricks, shift to Best Practice alone would lead to a reduction in the energy consumption from 375 PJ to 285 PJ resulting in a saving of 5 million tonnes of coal per annum. Further savings in energy and emissions would result from introduction of new technology; the technology currently under consideration being the Vertical Shaft Brick Kilns (VSBK). It is our assessment that the present installed capacity of 46.5 billion bricks could be transformed by adopting the Best Practice and any additional capacity created would be on the basis of new technology. This move would result in further improvement in energy efficiency and result in lowering of the total energy consumption to 260 PJ (13.8 million tons of coal) for the projected demand of 2020. The energy saving potential is equivalent to 6.1 million tonnes of coal per annum. The significant outcome of the combined effort of retrofitting the existing kilns with best practice technology and meeting of the additional capacity with new technology would result in a total energy saving of 35% compared to energy consumption based on present mix of technologies. Implementation Strategy for Augmentation of Supply An alternative have been examined in the study which takes into account the need for augmentation of supply of walling materials but limits the supply of burnt bricks. The saturation level of bricks has been assumed to be 46.5 billion bricks and it is assumed that this level of supply will be available on a sustained basis upto 2020. The balance requirement of bricks will be augmented through the supply of concrete products. The justification for invoking substitution through alternatives is that the housing trends established during the last two decades are a clear pointer towards increased use of concrete products. Further, at the regional level such a technology shift has already taken place in different geographical areas in India where local production of burnt bricks is no longer economically viable and concrete blocks are preferred. A scenario which looks at wider use of concrete blocks as substitute for burnt bricks appears very likely. In order to meet the projected demand of housing, the number of concrete blocks required to fully complement the supply of bricks have been evaluated. By this year 2000 a total of 3.3 billion concrete blocks will be required which will grow to a requirement of 9.5 billion blocks by 2020. In the final analysis by 2020, 50% of the volume of walling will be provided through concrete blocks. This will entail an annual requirement of cement equivalent to 10 million tonnes which is well within the projected supply of cement and require 50 million cubic metre of stone which can be met through capacity of two hundred and twenty eight stone crushers. The production capacity would translate into a requirement of 10,000 small scale production units for concrete blocks to be installed by the year 2000. The overall strategy that is envisaged for augmenting the supply as well as incorporating efficient resource utilisation would translate into a sequence of technology shifts characterised by :
The impact of each of these measures has been evaluated in terms of the energy requirements, energy savings possible and resource utilisation. The adoption of best practice for 46.5 million bricks alone results in a saving of 3.3. million tonnes of coal by 2000. The substitution by concrete blocks further limits the requirement of energy resulting in a saving of 14 PJ by 2020. A partial replacement of existing brick kilns by VSBK technology would limit the energy requirement even further. The maximum saving that can be achieved while fulfilling the demand requirements, is 4.4 million tonnes of coal for walling purposes alone in 2000 growing to 7 million tonnes of coal by 2020 (Fig. 5). The associated reduction possible in emissions is indicated in Figure (6). Sustainable Production Systems Such a scenario involving major technology shifts for providing building material alternatives needs to be optimised in the context of other environmental and policy considerations. The factors that have been analysed to evaluate these options are:
Improvement of energy efficiency While comparing the energy usage in the manufacture of cement and bricks, it is evident that the energy efficiency in cement production has improved by leaps and bounds. More than 70% of the large scale cement industry is already adopting the Dry-process which is close to the current Best-Practice. Similar improvements have failed to take place in the case of brick manufacture. In the specific case of Uttar Pradesh which has 13,000 operating kilns, only 600 have adopted improved technology. The improvement in fuel efficiency upto 25% is possible only through retrofitting of the existing kilns by installation of fixed chimneys in place of the widely used movable chimneys. The resistance in the adoption of technology is mainly due to institutional barriers. The prime reason given by kiln owners for persisting with movable chimneys was the practice of moving kiln sites which were determined by availability of lease land used for excavation of soil. The introduction of a uniform taxation procedure has alleviated some of the problems associated with construction of fixed chimneys. The switch to the best practice technology can be expedited in view of the recent environmental regulations regarding emissions, particularly SPM standards. According to the regulations newly introduced, the movable chimneys must be phased out by year 1997. The emergence of such a favourable environment for accelerating technology change can be strengthened by providing technological including re-training of the kiln operators and firemen. The kiln owners can be motivated by improved access to credit for retrofitting purposes. It should also be mentioned that such changes have already taken place in areas of Punjab where exorbitant fuel and fuel transportation costs have resulted in a marked shift to fixed chimneys. A case for decentralised production of alternative walling materials It is clear from all the previous measures that improvement in energy efficiency of brick manufacture will essentially provide a stable supply of walling materials; limited to the manufacture 46.5 billion bricks per year. Further augmentation of supply of building materials for walling is achievable through the use of concrete blocks. An energy analysis of solid concrete blocks has been done by aggregating the energy consumed in the manufacture of each of the components i.e. cement, aggregate and sand. This net figure is compared with the energy usage in the manufacture of burnt bricks. In order to compare these elements, the figures have been normalised for equivalent performance in walling applications and are given in the Table (4).
In the case of concrete blocks, the standard width of a load bearing wall is 20cms while for a burnt brick wall, the corresponding width is 23 cms. On the basis of their respective dimensions, the energy content per square metre of walling with concrete blocks is 164 MJ and with bricks is 495 MJ. The apparent low energy content of the solid concrete blocks is due to the lean quantity of cement required to bind a matrix of stone aggregates and sand. In terms of equivalance of performance, the utilisation of material resources in both bricks and concrete blocks is almost identical. There are several options for manufacture of concrete blocks by utilizing low energy materials and industrial wastes. This study has specifically examined the case of Bundelkhand where cover hundred stone crushers generate crushed stone of size less than 10mm which is classified as a waste. This resource can be easily incorporated into the manufacture of concrete blocks along with flash in proportions upto 10% to replace sand. In terms of energy efficiency alone, use of concrete blocks as a viable alternative for augmenting the supply of walling materials is justifiable. The concrete block manufacture is also amenable to small decentralised production using equipment and machinery which would typically require 2 kWh for manufacturing 400 blocks per hour. The output of such a decentralised production system would be typically one third the quantum of walling material originating from a Bull’s Trench kiln. The production of concrete blocks can be assured throughout the year and is not subject to vagaries of weather. The brick kiln production is, however, adversely affected during the monsoon season. In terms of the decentralised production capability, the requirement of 3.3 billion blocks would translate into setting up of 10,000 small decentralised production units by year 2000. The production capacity of machine manufactures does not appear to be a problem as there are over twenty reputed machine producers in the country. the capital requirement for the concrete block machines is estimated to be Rs. 25 crores in comparison to Rs. 60 crores required as capital for augmenting the supply through burnt bricks alone. Further the concrete block machines can produce diverse products like hollow blocks, solid blocks and stonecrete blocks. Material movement factor (MMF) The analysis has thus far focused on utilisation of material resource and energy efficiency. A strategy for alternative building materials needs to closely examine the quantum of transportation required for movement of raw materials, fuel and finished goods. The material movement involved in the manufacture of various building materials has been evaluated. The Material Movement Factor is quantified as the product of the bulk weight of raw materials moved (kg) and the distance of their movement (kms). In the case of burnt bricks, the Material Movement Factor is generally 345 kg. km for common practice kilns attributed mainly to movement of coal. For the case of solid concrete blocks the comparable figure is 160-180 kg. km including transportation of cement through an average distance of 500 kms. The published annual results of cement companies report that the freight component forms a very significant element of the market price of cement. In the case of cement, the fuel and the finished products are both moved over large distances? The efficient use of cement in concrete blocks makes it presently a much favoured option than the use of burnt bricks. However, by invoking energy efficiency in brick manufacture to the level of best practice, the material movement factor can be reduced to 210 kg.km which is comparable to the factor for concrete blocks. The Material Movement Factor can be an important index for comparing options of technology and alternative building materials. While the role of concrete blocks in augmenting supply of walling materials is unarguable, the MMF related to cement transportation is a major concern. For the entire quantity of 3.3 billion concrete blocks, the cement requirement is approximately 3 million tons for which material movement of 3000 million – tonnes km will be incurred. It is our proposition that the Material Movement Factor and hence the energy for transportation can be significantly reduced through the promotion of mini-cement plants. The distributive effect of mini cement plants would inhibit excessive movement of finished cement from large plants and provide other environmental and economic benefits. The fuel used for mini cement plants is coke breeze; widely regarded as a waste material. The mini cement plants can also be set up where smaller deposits of limestone are available. A comparison of the energy consumption in cement manufacture shows that mini cement plants are at least comparable in performance to the best Dry process. A strategy for large scale use of concrete blocks also provides a major opportunity for promotion of the best practice Vertical Shaft Kilns; a technology currently available in India for cement manufacture. Similarly a thrust in the utilisation of wastes like flyash, coupled with local time production could initiate production of pozzolonic cements (known locally as FalG as they are flyash-lime-gypsum based) and blocks for the local demand centres. The failure of the large capital intensive plants presently engaged in flyash utilisation is because of the centralised nature of production and problems and costs associated with transportation and distribution. The Government, through agencies like the Building Material and Technology Promotion Council (BMTPC), is already promoting these ventures by providing fiscal incentives like waiver of excise duty. It is the success of the Fal-G cement which is now a commonly used material in walling and even roofing in the Andhra Pradesh areas that needs to be understood and replicated. There have also been sporadic cases of industries like the Indian Tobbacco Company’s (ITC) Bhadrachalam paper mills involved in promotion of alternate materials by utilising its waste: lime and flyash in the form of masonry units. The industry plans to meets its own requirement of construction materials through this combination of wastes. Energy Pricing : An examination of Table 5 below of cost components of some materials, will show that the process for manufacture and distribution of cement entails significant cost of transportation of finished goods and energy costs for the manufacture of cement. As the use of cement and cement product becomes widely accepted, a control mechanism needs to be invoked for rationalisation of the energy costs. The energy analysis of different walling materials will show that the fuel cost per metre for walling in the case of concrete blocks, is Rs. 11.00 for a net energy consumption of 164MJ. This is derived as the energy equivalent of the fuels used i.e. coal and electricity (assumed to be generated from coal and diesel). In the case of burnt bricks, the costs of fuel is considerably high and has been evaluated to be Rs. 40/- per sqm. Mainly due to costs of coal. The corresponding energy for walling from burnt brick is 495 MJ.
An analysis which would ensure equivalence of fuel costs per unit energy for best practice in cement and brick manufacture provides some valuable insights. The cost per unit every being paid by the large cement industry for high quality coal, electricity and diesel appears to be only80% of the equivalent price envisaged in brick manufacture. A policy which provides equivalence to the use of bricks within a local area and use of concrete blocks within its own local area would suggest that the present cost incurred by the cement industry for energy of Rs. 470/- per ton, would need to be revised upwards to Rs. 600/- per ton to ensure party. This factor assumes additional importance in view of the factor that presently cement is transported over large distances aided by subsidised transportation costs. Though the suggested pricing is only indicative, the whole issue of energy costs particularly related to electricity and diesel need to be examined in greater detail. This is also assuming higher importance in view of the current trends to install large generation capacities of electricity through diesel generating sets. Conclusion The case study of walling has provided insights into evolving strategies for sustainable production systems. From the previous section, it became evident that energy efficiency upto 25% could be achieved through introduction of technologies for the production of four basic materials. By invoking a saturation in brick production at the level of 46.5 billion bricks per year, the strategy for augmentation of supply has focused on the use of cement-based concrete blocks. Even though the cement production is an energy intensive process, the efficient use of cement along with other low energy natural materials can result in enhancing energy and resource efficiency. This single action involving technology improvement and partial material substitution, has a potential of energy saving of 33% of the technology-as-Usual projections. It is estimated that by judicious substitution of natural building materials like earth and stone combined with the use of industrial wastes and lime (in preference to cement), the total energy requirement can be reduced to 50% of the present trends of production technology and usage of materials. A similar exercise is possible for roofing options and roofing technologies. This study has focused on technology issues, technology options and factors that influence technology change and substitution. Simultaneous measures at the policy level are needed to integrate issues concerning energy pricing, setting of emission standards and institutional measures that can be used to trigger these technology changes. |
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