"In the Danish town of Kalundborg, a number of industrial companies exchange waste and resources with each other in an elaborate network of pipelines. The cooperation is known as ”Kalundborg Symbiosis”. Among the participants are a refinery, a power plant, an enzyme producer, a producer of insulin, and a manufacturer of gypsum board.
These companies send waste from their production process on to other companies in the system, which can then use this as valuable input for their process. Steam, sludge, fly ash or hot water are some of the resources exchanged." (http://we-economy.net/?page_id=529)
- case study details via http://we-economy.net/?page_id=529