owners. The result has been that urban industrial areas, which from an industrial ecology standpoint are in many ways ideal locations for industrial facilities, have been virtually impossible to use. The governmental and legal systems need to devise a means around this difficulty. (Environmental liability difficulties in urban areas are sometimes secondary to such factors as crime, congestion, and high taxes [Boyd and Macauley, 1994]).
For facilities of any kind built on land not previously used for industrial or commercial purposes, one can anticipate that there will be ecological impacts on regional biodiversity as well as added air emissions (from construction and use of new transportation and utility infrastructures) and water emissions (from sanitary facilities and manufacturing activities). These effects can be minimized by using as much as possible existing infrastructures and developing the site by leaving the maximum area in its natural form. Nonetheless, given the current overstock of commercial buildings and facilities in many countries, such "greenfield" choices are hard to justify from an industrial ecology perspective.
Evaluation of existing infrastructure also requires consideration, and possibly redesign, of other local operations. Within each facility, for example, it is sometimes possible to use a residue stream from one process as a feed stream for another, to use excess heat from one process to provide heat for another, and so on. Such actions constitute steps toward a facility ecosystem. Chemical manufacturing plants, in particular, have made good progress along these lines.
Opportunities also exist to establish portions of industrial ecosystems when facilities owned by different parent companies agree to share residual products or residual energy. Such an approach is encouraged by geographical proximity. For example, the AT&T manufacturing plant in Columbus, Ohio, is about 1 km from a solid-waste landfill that emits methane gas, a by-product of the biodegradation of landfilled material. AT&T purchases the gas from the landfill and pipes it to its plant boiler, where the gas furnishes up to 25 percent of the necessary energy for manufacturing. At the same time, emissions of methane into the air, a greenhouse gas, are reduced.
More complex arrangements are possible, especially if planning is done before facilities are built. These involve establishing close relationships with suppliers, customers, and neighboring industries, and working with those partners to close materials cycles. In the same way that close relationships promote just-in-time delivery of supplies and components, so, too, can those relationships help corporations implement environmentally responsible manufacturing.
An outstanding and still unique example of the partnership approach exists in Kalundborg, Denmark, where 10 years of effort have culminated in the interactive network shown in Figure 1 (Graedel and Allenby, 1995; Terp, 1991). Four main participants are involved: the Asnaesverket Power Company, a Novo Nordisk pharmaceutical plant, a Gyproc facility for producing wallboard, and a Statoil refinery. Steam, gas, cooling water, and gypsum are exchanged among the participants, and some heat also is used for fish farming and residential green-