Industrial Ecology

Industrial ecology is an emerging new paradigm that concerns methods for increasing industrial efficiency and improving the relationships between industry and the environment (Graedel and Allenby, 2003; Lifset, 2000; McDonough and Braungart, 2002; Richards, 1997; Richards and Pearson, 1998; Socolow et al., 1994). It is relevant in this chapter on solid waste management because it emphasizes energy and material flows often with a focus on two management methods described earlier: source reduction and recycling (Graedel, 1994). One version of industrial ecology is for a particular industry to become "green" by improving its material cycle (Goldberg and Middleton, 2000; Stevens, 2002). The existing field arose in the 1990s with initiatives from industrial engineers, so it is a very recent development with many ideas and proposals but few working examples. A journal entitled Industrial Ecology was begun in 1998, and the International Society for Industrial Ecology was formed in 2001.

One of the most interesting features of industrial ecology in the context of ecological engineering is that it uses ecology as a model for examining industries, as noted in the quote by Richards et al. (1994) below:

Industrial ecology offers a unique systems approach within which environmental issues can be comprehensively addressed. It is based on an analogy of industrial systems to natural ecological systems ...

There are obviously limits to this analogy, but it can help illuminate useful directions in which the system might be changed. Consider, for instance, waste minimization at a scale larger than that of a single unit or facility in light of the biological analogue. A mature natural ecological community operates as a waste minimization system. In general, the waste produced by one organism, or by one part of the community, is not disposed of as waste by the total system as long as it is a source of useful material

Basic

Material

Productio

Manufacturing

Virgin ' Resources

Replenishing Loops

Independence of the lifetimes of linked compatible systems, products, and components

Waste

Waste

Replenishing Loops

Independence of the lifetimes of linked compatible systems, products, and components

FIGURE 6.10 The spiraling process from industrial ecology, which has similarities with material processing in ecosystems. (From Stahel, W. R. 1994. The Greening of Industrial Ecosystems. B. R. Allenby and D. J. Richards (eds.). National Academy Press, Washington, DC. With permission.)

and energy. Some organism, some part of the ecological system, tends to evolve or adjust to make a living out of any particular waste .

In an industrial ecology, unit processes and industries are interacting systems rather than isolated components. This view provides the basis for thinking about ways to connect different waste-producing processes, plants, or industries into an operating web that minimizes the total amount of industrial material that goes to disposal sinks or is lost in intermediate processes. The focus changes from merely minimizing waste from a particular process or facility, commonly known as "pollution prevention," to minimizing waste produced by the larger system as a whole.

Industrial ecology uses ecological principles but not actual living organisms to design new systems. David Tilley (personal communication) suggests that in industrial ecology "the ecosystem provides the software for industrial design." Thus, industrial ecology can be thought of as an abstract form of ecological engineering or perhaps as a kind of reverse engineering based on natural ecosystems. For example, Figure 6.10 illustrates some of the strategies of this new field including waste prevention and reduction, product-life extension, and recycling, and is quite reminiscent of the resource spiraling concept from ecology (see Chapter 2). A more concrete example is given by Klimisch (1994) in which the automobile industry is depicted like an ecosystem with trophic levels, material flows, and recycling. Benefits will accrue to both society and the environment if industrial ecology as a field can mature and result in working models. Ecological engineers may be able to help develop the new ideas of industrial ecology since they have backgrounds in both ecology and engineering.

Although industrial ecology is clearly a recent development there are historic precedents for the field. Henry Ford may have been the first true industrial ecologist as evidenced by a number of efforts undertaken from about 1910 until his death in 1948 [though Friedlander (1994) traces origins of the field back to Benjamin Franklin in colonial America]. Ford is best known for developing affordable cars, utilizing mass production techniques, and creating one of the first industrial empires in the U.S. However, he maintained an interest in agriculture throughout his life and continually tried to create compatible system of agriculture and industry (Bryan, 1990; Wik, 1972). For example, his village industry idea has been proposed as a

Waste By-product

FIGURE 6.11 Energy circuit diagram illustrating the concept of valuation of waste byproducts.

Waste By-product

Intended

Useful

Product

Intended

Useful

Product

FIGURE 6.11 Energy circuit diagram illustrating the concept of valuation of waste byproducts.

model for sustainable development (Kangas, 1997) because it combined farms with local manufacturing plants fueled with renewable energy sources. Ford was also a leader in the "Chemurgy" movement that was popular during the Depression period. Chemurgy, which is a term analogous to metallurgy, attempted to produce and utilize industrial materials derived from agricultural crops. Soybeans were the focus of a major research effort by the Ford Motor Company. This crop was used to produce a number of items such as oils, paints, varnishes, and plastic-like parts for automobiles. Ford wanted to control all of the raw materials that went into his cars and to utilize as much of the waste products from the automobile as possible. According to Wik (1972), because of Ford's interest in recycling,

... engineers in his company tried to salvage everything from floor sweepings to platinum. Wood shavings were converted into charcoal briquets, formaldehyde, creosote, and ethyl acetate. Coal derivatives yielded coke, benzol, and ammonium sulfate, while the slag from steel furnaces was used for surfacing roads. In 1925 the company sold coke commercially as well as ammonium sulfate as fertilizer. Eighty-eight gas stations in Detroit sold benzol to auto drivers at the same price as gasoline. Seven tons of Dearborn garbage were distilled daily in the River Rouge plant where it yielded alcohol, refined oil, and gas suitable for heating purposes. Residues were mixed with sand and sold as fertilizer to greenhouses. Tests were made to extract soap from the sewage in Detroit. Sale of the various Ford by-products in 1928 amounted to $20 million. The New York Times in 1930 claimed Ford threw nothing away, not even the smoke from his factories.

A thorough review of Henry Ford's work may provide many examples that can inspire modern industrial ecology efforts.

The simple diagram shown in Figure 6.11 illustrates the idea of wastes. A process exists (the work gate on the left) in which energy is transformed to create an intended, useful product, which is subsequently used as an input in another process (the work

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