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10 - Industrial Ecology.pdf

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10 - Industrial Ecology.pdf

  1. 1. Lecture 10: INDUSTRIAL ECOLOGY 1
  2. 2. Industrial ecology • is an approach based upon systems engineering and ecological principles that integrates the production and consumption aspects of the design, production, use, and termination (decommissioning) of products and services in a manner that minimizes environmental impact while optimizing utilization of resources, energy, and capital. • The practice of industrial ecology represents an environmentally acceptable, sustainable means of providing goods and services. 2
  3. 3. • Industrial ecology works within a system of industrial ecosystems, which mimic natural ecosystems. • Natural ecosystems, usually driven by solar energy and photosynthesis, consist of an assembly of mutually interacting organisms and their environment, in which materials are interchanged in a largely cyclical manner. • An ideal system of industrial ecology follows the flow of energy and materials through several levels, uses wastes from one part of the system as raw material for another part, and maximizes the efficiency of energy utilization. • Whereas wastes, effluents, and products used to be regarded as leaving an industrial system at the point where a product or service was sold to a consumer, industrial ecology regards such materials as part of a larger system that must be considered until a complete cycle of manufacture, use, and disposal is completed. 3
  4. 4. industrial ecology • is all about cyclization of materials • The goal is cradle to reincarnation, since if one is practicing industrial ecology correctly there is no grave.” • cyclization of materials should occur at the highest possible level of material purity and stage of product development. 4
  5. 5. • industrial metabolism, which refers to the ways in which an industrial system handles materials and energy, extracting needed materials from sources such as ores, using energy to assemble materials in desired ways, and disassembling materials and components. • In this respect, an industrial ecosystem operates in a manner analogous to biological organisms, which act on biomolecules to perform anabolism (synthesis) and catabolism (degradation). • Just as occurs with biological systems, industrial enterprises can be assembled into industrial ecosystems. • Such systems consist of a number (preferably large and diverse) of industrial enterprises acting synergistically and, for the most part, with each utilizing products and potential wastes from other members of the system. • The term sustainable development has been used to describe industrial development that can be sustained without environmental damage and to the benefit of all people. • “sustainable development” must evolve in which use of nonrenewable resources is minimized insofar as possible, and the capability to produce renewable resources (for example, by promoting soil conservation to maintain the capacity to grow biomass) is enhanced. 5
  6. 6. INDUSTRIAL ECOSYSTEMS • A group of firms that practice industrial ecology through a system of industrial metabolism that is efficient in the use of both materials and resources constitute a functional industrial ecosystem. • Such a system can be defined as a regional cluster of industrial firms and other entities linked together in a manner that enables them to utilize byproducts, materials, and energy between various enterprises in a mutually advantageous manner. • the main attributes of a functional industrial ecosystem, which, in the simplest sense, processes materials powered by a relatively abundant source of energy. • Materials enter the system from a raw materials source and are put in a usable form by a primary materials producer. • From there the materials go into manufacturing goods for consumers. • Associated with various sectors of the operation are waste processors that can take byproduct materials, upgrade them, and feed them back into the system. • An efficient, functional transportation system is required for the system to work well, and good communications links must exist among the various sectors. • A key material in the system is water, and it is often in limited supply in highly populated arid regions of the world. 6
  7. 7. • A successfully operating industrial ecosystem provides several benefits: ✓Such a system reduces pollution. ✓It results in high energy efficiency compared to systems of firms that are not linked and it reduces consumption of virgin materials because it maximizes materials recycle. ✓Reduction of amounts of wastes is another advantage of a functional system of industrial ecology. ✓increased market value of products relative to material and energy consumption. • An industrial ecosystem can be set up using two basic complementary approaches. 1. emphasis may be placed upon product durability and amenability to repair and recycle, which are compatible with the practice of industrial ecology. Instead of selling products, a concern may emphasize leasing so that it can facilitate recycling. 2. emphasizes interactions between concerns so that they operate in keeping with good practice of industrial ecology. This approach facilitates materials and energy flow, exchange, and recycle between various firms in the industrial ecosystem. 7
  8. 8. THE FIVE MAJOR COMPONENTS OF AN INDUSTRIAL ECOSYSTEM • It is useful to define five major components of an industrial ecosystem: 1. a primary materials producer, 2. a source or sources of energy, 3. a materials processing and manufacturing sector, 4. a waste-processing sector, and 5. a consumer sector. • In such an idealized system, the flow of materials among the four major hubs is very high. • Each constituent of the system evolves in a manner that maximizes the efficiency with which the system utilizes materials and energy. 8
  9. 9. 1. Primary Materials and Energy Producers • It is convenient to consider the primary materials producers and the energy generators together because both materials and energy are required for the industrial ecosystem to operate. • The primary materials producer or producers may consist of one or several enterprises devoted to providing the basic materials that sustain the industrial ecosystem. • Most generally, in any realistic industrial ecosystem a significant fraction of the material processed by the system consists of virgin materials. • In a number of cases, and increasingly so as pressures build to recycle materials, significant amounts of the materials come from recycling sources. 9
  10. 10. • The processes that virgin materials entering the system are subjected to vary with the kind of material, but can generally be divided into several major steps. • Typically, the first step is extraction, designed to remove the desired substance as completely as possible from the other substances with which it occurs. • A concentration step may follow extraction to put the desired material into a purer form. • After concentration, the material may be put through additional refining steps that may involve separations. • Following these steps, the material is usually subjected to additional processing and preparation leading to the finished materials. • Throughout the various steps of extraction, concentration, separation, refining, processing, preparation, and finishing, various physical and chemical operations are used, and wastes requiring disposal may be produced. • Recycled materials may be introduced at various parts of the process, although they are usually introduced into the system following the concentration step. 10
  11. 11. 2. Materials Processing and Manufacturing Sector • Finished materials from primary materials producers are fabricated to make products in the materials processing and manufacturing sector. • For example, the manufacture of an automobile requires steel for the frame, plastic for various components, rubber in tires, lead in the battery, copper in the wiring, and cloth or leather for the seats, along with a large number of other materials. • The materials processing and manufacturing sector presents several opportunities for recycling. • At this point, it might be useful to define two different streams of recycled materials: • Process recycle streams consisting of materials recycled in the manufacturing operation itself • External recycle streams consisting of materials recycled from other manufacturers or from postconsumer products • Materials suitable for recycling can vary significantly. • Generally, materials from the process recycle streams are quite suitable for recycling because they are the same materials used in the manufacturing operation. • Recycled materials from the outside, especially those from postconsumer sources, may be quite variable in their characteristics because of the lack of effective controls over recycled postconsumer materials. . 11
  12. 12. 3. The Consumer Sector • In the consumer sector, products are sold or leased to the consumers who use them. • The duration and intensity of use vary widely with the product; paper towels are used only once, whereas an automobile may be used thousands of times over many years. • In all cases, however, the end of the useful lifetime of the product is reached and it is either (1) discarded or (2) recycled. • The success of a total industrial ecology system can be measured largely by the degree to which recycling predominates over disposal. 12
  13. 13. 4. Waste Processing Sector • Recycling has become so widely practiced that an entirely separate waste processing sector of an economic system can now be defined consisting of enterprises that deal specifically with the collection, separation, and processing of recyclable materials and their distribution to end users. • Such operations may be entirely private or they may involve cooperative efforts with governmental sectors. • They are often driven by laws and regulations as well as positive economic and regulatory incentives for their recycle. 13
  14. 14. LEVELS OF MATERIALS UTILIZATION • There are two extremes in levels of materials utilization in industrial systems. • At the most inefficient level, as shown in Figure 19.3, raw materials are viewed as being unlimited and no consideration is given to limiting wastes. • Such an approach was typical of industrial development in the U.S. in the 1800s and early 1900s when the prevailing view was that there were no limits to ores, fossil energy resources, and other kinds of raw materials; it was generally held that the continent had an unlimited capacity to absorb industrial wastes. 14
  15. 15. • A second kind of industrial system in which both raw materials and wastes are limited to greater or lesser extents is illustrated in Figure 19.4. • Such a system has a relatively large circulation of materials within the industrial system as a whole, compared with reduced quantities of material going into the system and relatively lower production of wastes. • Such systems are typical of those in industrialized nations and modern economic systems in which shortages of raw materials and limits to the places to put wastes are beginning to be felt. • Even with such constraints, large quantities of materials are extracted, processed, and used, then either disposed of in the environment in concentrated form (hazardous wastes) or dispersed. 15
  16. 16. • An industrial ecosystem with no materials input and no wastes is illustrated in Figure 19.5. • The material flows within the system itself are quite high. • In addition, the energy requirements of such a system can be rather high, and a key to its successful operation is often an abundant, minimally polluting primary source of energy. • Such a system is an idealized one that can never be realized in practice, but it serves as a useful goal around which more-practical and achievable systems can be based. 16
  17. 17. CONSIDERATION OF ENVIRONMENTAL IMPACTS IN INDUSTRIAL ECOLOGY • By its nature, industrial production has an impact upon the environment. • Whenever raw materials are extracted, processed, used, and eventually discarded, some environmental impacts will occur. • In designing an industrial ecological system, several major kinds of environmental impacts must be considered in order to minimize them and keep them within acceptable limits. • For most industrial processes, the first environmental impact is that of extracting raw materials. • This can be a straightforward case of mineral extraction, or it can be less direct, such as utilization of biomass grown on forest or crop land. • A basic decision, therefore, is the choice of the kind of material to be used. • Wherever possible, materials should be chosen that are not likely to be in short supply in the foreseeable future. • As an example, the silica used to make the lines employed for fiber-optics communication is in unlimited supply and a much better choice for communication lines than copper wire made from limited supplies of copper ore. 17
  18. 18. • Industrial ecology systems should be designed to reduce or even totally eliminate air pollutant emissions. • Among the most notable recent progress in that area has been the marked reduction and even total elimination of solvent vapor emissions (volatile organic carbon, VOC), particularly those from organochlorine solvents. • Some progress in this area has been made with more-effective trapping of solvent vapors. • In other cases, the use of the solvents has been totally eliminated. • This is the case for chlorofluorocarbons (CFCs), which are no longer used in plastic foam blowing and parts cleaning because of their potential to affect stratospheric ozone. • Other air pollutant emissions that should be eliminated are hydrocarbon vapors, including those of methane, CH4, and oxides of nitrogen or sulfur. • Discharges of water pollutants should be entirely eliminated wherever possible. • For many decades, efficient and effective water treatment systems have been employed that minimize water pollution. • However, these are “end of pipe” measures, and it is much more desirable to design industrial systems such that potential water pollutants are not even generated. 18
  19. 19. • Industrial operations should be designed to prevent production of liquid water-based or organic solvent-based wastes that may have to be sent to a waste processor. • Under current conditions, the largest single constituent of so-called “hazardous wastes” is water. • Elimination of water from the waste stream automatically prevents pollution and reduces amounts of wastes requiring disposal. • The solvents in organic wastes largely represent potentially recyclable or combustible constituents. • A properly designed industrial ecosystem does not allow such wastes to be generated or to leave the factory site. • In addition to liquid wastes, many solid wastes must be considered in an industrial ecosystem. • The most troublesome are toxic solids that must be placed in a secure hazardous-waste landfill. • The problem has become especially acute in some industrialized nations in which the availability of landfill space is severely limited. • In a general sense, solid wastes are simply resources that have not been properly utilized. • Closer cooperation among suppliers, manufacturers, consumers, regulators, and recyclers can minimize quantities and hazards of solid wastes. 19
  20. 20. • Whenever energy is expended, there is a degree of environmental damage. • Therefore, energy efficiency has a high priority in a properly designed industrial ecosystem. • Significant progress has been made in this area in recent decades, as much because of the high costs of energy as for environmental improvement. • More-efficient devices, such as electric motors, and approaches, such as cogeneration of electricity and heat, that make the best possible use of energy resources are highly favored. • An important side benefit of more-efficient energy utilization is the lowered emissions of air pollutants, including greenhouse gases. 20
  21. 21. THREE KEY ATTRIBUTES: ENERGY, MATERIALS, DIVERSITY • By analogy with biological ecosystems, a successful industrial ecosystem should have (1) renewable energy, (2) complete recyling of materials, and (3) species diversity for resistance to external shocks. Unlimited Energy • Energy is obviously a key ingredient of an industrial ecosystem. • Unlike materials, the flow of energy in even a well-balanced closed industrial ecosystem is essentially one-way in that energy enters in a concentrated, highly usable form, such as chemical energy in natural gas, and leaves in a dilute, disperse form as waste heat. • An exception is the energy that is stored in materials. • This can be in the form of energy that can be obtained from materials, such as by burning rubber tires, or it can be in the form of what might be called “energy credit,” which means that by using a material in its refined form, energy is not consumed in making the material from its raw material precursors. • A prime example of this is the “energy credit” in metals, such as that in aluminum metal, which can be refined into new aluminum objects requiring only a fraction of the energy consumed to refine the metal from aluminum ore. • On the other hand, recycling and reclaiming some materials can require a lot of energy, and the energy consumption of a good closed industrial ecosystem can be rather high. 21
  22. 22. • Natural ecosystems run on unlimited, renewable energy from the sun or, in some specialized cases, from geochemical sources. • Successful industrial ecosystems must also have sources of energy that are not severely limited by either supply or potential for environmental damage in order to be sustained for an indefinite period of time (solar) • However, solar sources present formidable problems, not the least of which is that they work poorly during those times of the day and seasons of the year when the sun does not shine. • Even under optimum conditions, solar energy has a low power density necessitating collection and distribution systems of an unprecedented scale if they are going to displace present fossil energy sources. • Other renewable sources, such as wind, tidal, geothermal, biomass, and hydropower present similar challenges. • It is likely, therefore, that fossil energy sources will provide a large share of the energy for industrial ecosystems in the foreseeable future. • This assumes that a way can be found to manage greenhouse gases. • At the present time, it appears that injection of carbon dioxide from combustion into deep ocean regions is the only viable alternative for sequestering carbon dioxide, and this approach remains an unproven technology on a large scale. • (One potential problem is that the slight increase in ocean water pH of about 1/10 pH unit could be detrimental to many of the organisms that live in the ocean.) 22
  23. 23. • Nuclear fusion power remains a tantalizing possibility for unlimited energy, but so far practical nuclear fusion reactors for power generation have proven an elusive target. • Unattractive as it is to many, the only certain, environmentally acceptable energy source that can without question fill the energy needs of modern industrial ecology systems is nuclear fission energy. • With breeder reactors that can generate additional fissionable material from essentially unlimited supplies of uranium-238, nuclear fission can meet humankind’s energy needs for the foreseeable future. • Of course, there are problems with nuclear fission—more political and regulatory than technical. • The solution to these problems remains a central challenge for humans in the modern era. 23
  24. 24. Industrial Ecology and Material Resources • A system of industrial ecology is successful if it reduces demand for materials from virgin sources. • Strategies for reduced material use may be driven by technology, by economics, or by regulation. • The four major ways in which material consumption can be reduced are • (1) using less of a material for a specific application, an approach called dematerialization; • (2) substitution of a relatively more abundant and safe material for one that is scarce or toxic; • (3) recycling, broadly defined; and • (4) extraction of useful materials from wastes, sometimes called waste mining. 24
  25. 25. Dematerialization • There are numerous recent examples of reduced uses of materials for specific applications. • One example of dematerialization is the transmission of greater electrical power loads with less copper wire by using higher voltages on long distance transmission lines. • Copper is also used much more efficiently for communications transmission than it was in the early days of telegraphy and telephone communication. • Amounts of silver used per roll of photographic film have decreased significantly in recent years. • The layer of tin plated onto the surface of a “tin can” used for food preservation and storage is much lower now than it was several decades ago. • In response to the need for greater fuel economy, the quantities of materials used in automobiles have decreased significantly over the last 2 decades, a trend reversed, unfortunately, by the more recent increased popularity of large “sport utility vehicles.” • Automobile storage batteries now use much less lead for the same amount of capacity than they did in former years. • The switch from 6-volt to 12-volt auto batteries in the 1950s enabled use of lighter wires, such as those from the battery to the electrical starter. • Somewhat later, the change to steel-belted radial tires enabled use of lighter tires and resulted in greatly increased tire lifetimes so that much less rubber was used for tires. 25
  26. 26. Substitution of Materials • Substitution and dematerialization are complementary approaches to reducing materials use. • The substitution of polyvinylchloride (PVC) siding in place of wood on houses has resulted in dematerialization over the long term because the plastic siding does not require paint. • Technology and economics combined have been leading factors in materials substitution. • A very significant substitution that has taken place over recent decades is that of aluminum for copper and other substances. • Copper, although not a strategically short metal resource, nevertheless is not one of the more abundant metals in relation to the demand for it. • Considering its abundance in the geosphere and in sources such as coal ash, aluminum is a very abundant metal. • Now aluminum is used in place of copper in many high voltage electrical transmission applications. • Aluminum is also used in place of brass, a copper-containing alloy, in a number of applications. • Aluminum roofing substitutes for copper in building construction. • Aluminum cans are used for beverages in place of tin-plated steel cans. 26
  27. 27. Recycling • For a true and complete industrial ecosystem, close to 100% recycling of materials must be realized. • In principle, given a finite supply of all the required elements and abundant energy, essentially complete recycling can be achieved. • A central goal of industrial ecology is to develop efficient technologies for recycling that reduce the need for virgin materials to the lowest possible levels. • Another goal must be to implement process changes that eliminate dissipative uses of toxic substances, such as heavy metals, that are not biodegradable and that pose a threat to the environment when they are discarded. • For consideration of recycling, matter can be put into four separate categories. • The first of these consists of elements that occur abundantly and naturally in essentially unlimited quantities in consumable products. • Materials in this category of recyclables are discharged into the environment and recycled through natural processes or for very low-value applications, such as sewage sludge used as fertilizer on soil. • A second category of recyclable materials consists of elements that are not in short supply, but are in a form that is especially amenable to recycling. • The best example of a kind of commodity in this class is paper. • Paper fibers can be recycled up to five times, and the nature of paper is such that it is readily recycled. 27
  28. 28. • A third category of recyclables consists of those elements, mostly metals, for which world resources are low. • A fourth category of materials to consider for recycling consists of parts and apparatus, such as auto parts discussed previously. • In many cases, such parts can be refurbished and reused. • Even when this is not the case, substantial monetary deposits collected from customers at the time of purchase can provide incentives for recycling. • For components to be recycled efficiently and easily, they must be designed with reuse in mind in aspects such as facile disassembly. • Combustion to produce energy can be a form of recycling. • For some kinds of materials, combustion in a power plant is the most cost-effective and environmentally safe way of dealing with materials. • This is true, for example, of municipal refuse that contains a significant energy value because of combustible materials in it as well as a variety of items that potentially could be recycled for the materials in them. • However, once such items become mixed in municipal refuse and contaminated with impurities, the best means of dealing with them is simply combustion. • It should be noted that recycling comes with its own set of environmental concerns. • One of the greatest of these is contamination of recycled materials with toxic substances. • Substances may become so mixed with use that recycling is not practical. 28
  29. 29. Extraction of Useful Materials from Wastes • Sometimes called waste mining, the extraction of useful materials from wastes has some significant, largely unrealized potential for the reduction in use of virgin materials. • Waste mining can often take advantage of the costs that must necessarily be incurred in treating wastes, such as flue gases. • There are several advantages to recovering a useful resource from wastes. • One of these is the reduced need to extract the resource from a primary source. • By using waste sources, the primary source is preserved for future use. • Another advantage is that extraction of a resource from a waste stream can reduce the toxicity or potential environmental harm from the waste stream. 29
  30. 30. Diversity and Robust Character of Industrial Ecosystems • Successful natural ecosystems are highly diverse, as a consequence of which they are also very robust. • Robustness means that if one part of the system is perturbed, there are others that can take its place. • Consider what happens if the numbers of a top predator at the top of a food chain in a natural ecosystem are severely reduced because of disease. • If the system is well balanced, another top predator is available to take its place. • The energy sector of industrial ecosystems often suffers from a lack of robustness. • Examples of energy vulnerability have become obvious with several “energy crises” during recent history. • Another requirement of a healthy industrial ecology system that is vulnerable in some societies is water. • In some regions of the world, both the quantity and quality of water are severely limited. • A lack of self-sufficiency in food is a third example of vulnerability. • Vulnerabililty in food and water are both strongly dependent upon climate, which in turn is tied to environmental concerns as a whole. 30
  31. 31. LIFE CYCLES: EXPANDING AND CLOSING THE MATERIALS LOOP • In a general sense, the traditional view of product utilization is the one-way process of • extraction → production → consumption → disposal. • Materials that are extracted and refined are incorporated into the production of useful items, usually by processes that produce large quant-ities of waste by-products. • After the products are worn out, they are discarded. • This essentially one-way path results in a relatively large exploitation of resources, such as metal ores, and a constant accumulation of wastes. • however, the one-way path outlined above can become a cycle in which manufactured goods are used, then recycled at the end of their life spans. • As one aspect of such a cyclic system, it is often useful for manufacturers to assume responsibility for their products, to maintain “stewardship.” • Ideally, in such a system a product or the material in it would have a never-ending life cycle; when its useful lifetime is exhausted, it is either refurbished or converted into another product. 31
  32. 32. • In considering life cycles, it is important to note that commerce can be divided into the two broad categories of products and services. • Whereas most commercial activity used to be concentrated on providing large quantities of goods and products, demand has been largely satisfied for some segments of the population, and the wealthier economies are moving more to a service-based system. • Much of the commerce required for a modern society consists of a mixture of services and goods. • The trend toward a service economy offers two major advantages with respect to waste minimization. • Obviously, a pure service involves little material, and a service provider is in a much better position to control materials to ensure that they are recycled and to control wastes, ensuring their proper disposal. • It is usually difficult to recycle products or materials within a single, relatively narrow industry. • In most cases, to be practical, recycling must be practiced on a larger scale than simply that of a single industry or product. • For example, recycling plastics used in soft drink bottles to make new soft drink bottles is not allowed because of the possibilities for contamination. • However, the plastics can be used as raw material for auto parts. • Usually, different companies are involved in making auto parts and soft drink bottles. 32
  33. 33. LIFE-CYCLE ASSESSMENT • From the beginning, industrial ecology must consider process/product design in the management of materials, including the ultimate fates of materials when they are discarded. • The product and materials in it should be subjected to an entire life-cycle assessment or analysis. • A life-cycle assessment applies to products, processes, and services through their entire life cycles from extraction of raw materials—through manufacturing, distribution, and use—to their final fates from the viewpoint of determining, quantifying, and ultimately minimizing their environmental impacts. • It takes account of manufacturing, distribution, use, recycling, and disposal. • Life-cycle assessment is particularly useful in determining the relative environmental merits of alternative products and services. • A basic step in life-cycle analysis is inventory analysis which provides qualitative and quantitative information regarding consumption of material and energy resources (at the beginning of the cycle) and releases to the anthrosphere, hydrosphere, geosphere, and atmosphere (during or at the end of the cycle). • It is based upon various materials cycles and budgets, and it quantifies materials and energy required as input and the benefits and liabilities posed by products. • The related area of impact analysis provides information about the kind and degree of environmental impacts resulting from a complete life cycle of a product or activity. • Once the environmental and resource impacts have been evaluated, it is possible to do an improvement analysis to determine measures that can be taken to reduce impacts on the environment or resources. 33
  34. 34. • In making a life-cycle analysis the following must be considered: • If there is a choice, selection of the kinds of materials that will minimize waste • Kinds of materials that can be reused or recycled • Components that can be recycled • Alternate pathways for the manufacturing process or for various parts of it • Although a complete life-cycle analysis is expensive and time-consuming, it can yield significant returns in lowering environmental impacts, conserving resources, and reducing costs. • This is especially true if the analysis is performed at an early stage in the development of a product or service. • Improved computerized techniques are making significant advances in the ease and efficacy of life-cycle analyses. • Until now, life-cycle assessments have been largely confined to simple materials and products such as reusable cloth vs. disposable paper diapers. • A major challenge now is to expand these efforts to more-complex products and systems such as aircraft or electronics products. 34
  35. 35. • Quiz next Dec 2 (Module 6-9) • Chapter 11 on Dec 9 • Exam TBA (Module 8-11) 35

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