A. Definition

Industrial ecology conceptualises industry as a man-made ecosystem that operates in a similar way to natural ecosystems, where the waste or by product of one process is used as an input into another process. Industrial ecology interacts with natural ecosystems and attempts to move from a linear to cyclical or closed loop system. Like natural ecosystems, industrial ecology is in a continual state of flux.

B. Main Features

Industrial processes, from material extraction through to product disposal, have an adverse impact upon the environment. Industrial ecology aims to reduce environmental stress caused by industry whilst encouraging innovation, resource efficiency and sustained growth. Industrial ecology acknowledges that industry will continue operate and expand however, it supports industry that is environmentally conscious and has less burden upon the planet. It views industrial sites as part of a wider ecology rather than an external, solitary entity.

Within the industrial ecology concept, industry interacts with nature and utilises the wastes and by products of other industries as inputs into its own processes. Industrial ecology ranges from purely industrial ecosystems to purely natural ecosystems with a range of hybrid industrial/natural ecosystems in between. Covering both industrial management and technology, industrial ecology encompasses other sustainability concepts and tools such as material flows analysis; environmentally sound technologies; design for disassembly; and dematerialisation.

The principles of industrial ecology as defined by Tibbs (1992) are:

• Create industrial ecosystems - close the loop; view waste as a resource; create partnerships with other industries to trade by-products which are used as inputs to other processes.
• Balance industrial inputs and outputs to natural levels - manage the environmental-industrial interface; increase knowledge of ecosystem behaviour, recovery time and capacity; increase knowledge of how and when industry can interact with natural ecosystems and the limitations.
• Dematerialisation of industrial output - use less virgin materials and energy by becoming more resource efficient; reuse materials or substituting more environmentally friendly materials; do more with less.
• Improve the efficiency of industrial processes - redesign products, processes, equipment; reuse materials to conserve resources.
• Energy use - incorporate energy supply within the industrial ecology; use alternative sources of energy that have less or no impact upon the environment.
• Align policies with the industrial ecology concept - incorporate environment and economics into organisational, national and international policies; internalize the externalities; use economic instruments to encourage a move towards industrial ecology; use a more appropriate discount rate; use a more comprehensive index to measure a nation's wealth rather than GNP.

The benefits of industrial ecology include: cost savings (materials purchasing, licensing fees, waste disposal fees, etc); improved environmental protection; income generation through selling waste or by products; enhanced corporate image; improved relations with other industries and organisations and market advantages. Limitations to industrial ecology include: no market for materials; lack of support from government and industry; reluctance of industry to invest in appropriate technology; perceived legal implications and reluctance to move to another supplier.

The formation of virtual or physical eco-parks arises from clusters of industry that agree to supply or sell waste to each other, thereby moving towards the industrial ecology concept. Most eco-parks are virtual due to the high cost associated with relocating facilities. However some physical eco-parks are being designed whereby certain industries are located on the same site.

C. Case Studies and Examples

1. Industry Partnerships
Since the 1970's several industries in Denmark have supplied or sold by products and wastes to other industries. Asnaes, the largest coal-fired power plant in Denmark, sold processed steam to Statoil (an oil refinery) and Novo Nordisk (a pharmaceutical plant). Some of Asnaes' surplus heat was supplied to the town's heating scheme, reducing the number of domestic oil burning systems in use. Surplus heat was also used to heat the water of Asnaes' commercial fish farm. Local farmers used sludge from the fish farm as fertilizer. By treating some of its waste, Novo Nordisk sold high nutrient liquid sludge to farmers. Statoil supplied cooling and purified waste water to Asnaes which reduced Asnaes' freshwater extraction. In addition, Statoil removed sulphur from its surplus gas and sold all of its cleaned surplus gas to Asnaes and Gyproc (a plasterboard factory). The removed sulfur was sold to Kemira (a sulfuric acid producer). By desulfurising its smoke, Asnaes sold the resulting calcium sulfate to Gyproc as an alternative to mined gypsum which was being imported.

These partnerships were formed voluntarily and negotiated independently. Initially for purely economic reasons, some of the later deals were made for environmental reasons.

D. Target Sectors / Stakeholders

The primary stakeholders are: business; industry; industry associations; engineers; research institutions; government; non-government organisations and economists.

E. Scale of Operation

Industrial ecology is best implemented within a reasonable transport distance between industries.

F. Links

• University of Michigan - Industrial Ecology, An Introduction
• US Department of Energy Smart Communities Network - Industrial Ecology
• Rockefeller University - Industrial Ecology, Some Directions for Research
• Tibbs H, 1992, Industrial Ecology: An Environmental Agenda for Industry