Modeled after the interconnection of ecological processes, industrial ecology redirects waste streams into usable materials by linking industries to one another, incorporating a spectrum of approaches such as dematerialization, life-cycle assessment, and product-oriented environmental policy.
Industrial ecology has also been applied to small-scale agricultural projects, such as Vermont's Intervale, and is occasionally associated with the appealing, if contentious, concept of 'zero emissions'. ZERI (Zero Emissions Research Initiative) has implemented community-scale projects in developing countries, aiming to increase communities' self-sufficiency, and setting examples for the developed world.
In order to find applications for (often toxic) waste materials, industrial ecology requires significant transparency betweeen industries; proprietary information and litigation are a couple of the major barriers to similar schemes in North America. The oft-cited success of Kalundborg - a Danish community with a tightly integrated industrial ecosystem - is due in no small part to the transparency and openness between the community's engineers:
"At the center of the Kalundborg industrial park is a large, coal-fired electrical power-generating station. Waste steam from the power plant runs a pharmaceutical plant and an oil refinery. Waste heat is piped to houses in the nearby town, replacing 3,500 household oil heaters. Waste water from the oil refinery goes back to the power plant, in place of fresh water that had previously been pumped from nearby Lake Tisso. Waste gas from the refinery runs a factory making gypsum wallboard, which also uses gypsum extracted from the power plant's wastes. Sulfur, a byproduct of the oil refinery, becomes sulfuric acid at yet another plant. Fly ash, left over from the power plant, is made into cement. The sludge from the pharmaceutical plant's yeast-based processes fertilizes farmers' fields. Like symbiosis between plants or animals, what one partner excretes the other needs."
These symbiotic relationships have drastically reduced Kalundborg's energy and water consumption, and output of greenhouse gases. What's interesting is that while it remains the favourite case study for industrial ecologies, most eco-industrial parks in development are planned from the bottom up, while Kalundborg self-organized to meet regulatory goals (and, if you like, evolved according to market forces):
"In some ways... government - or at least culture - does affect the level to which industries will act in symbiosis. "One of the unique aspects of culture in Denmark is that all the engineers in Kalundborg hung out together. They knew each other... Scandinavian economies have a somewhat different ethos in terms of their interface with the environment. It could be geography, it could be climate, it could be history, but for some reason they have more of a team attitude when it comes to dealing with environmental problems." "