Kalundborg Symbiosis of Denmark is a public-private alliance for converting waste materials from its member companies into the raw production materials for others. This enables increased production capacity without concomitant increases in water or energy consumption, while providing lower production costs, less waste management, and reduced environmental impact. The materials involved include steam, dust, various gases, mud, or any other material that can be physically transported between companies. Heat can also be reused.
The initiative, begun in 1961, was born of conversations between businesspeople and government authorities. Together, they forged a collaboration based on good communication and positive relationships. Kalundborg Symbiosis has gradually expanded to comprise nine members: the bioethanol producer Inbicon; Novo Nordisk, the world’s largest producer of insulin; Novozymes, the world’s largest producer of enzymes; Gyproc, which produces gypsum board; DONG Energy, which owns the Asnæs plant, the largest power plant in Denmark; RGS 90, which manages waste and contaminated soil; Statoil, which owns Denmark’s largest oil refinery; Kara/Novoren, a waste-treatment company; Kalundborg Forsyning, which handles water, heating and wastewater removal services for the city of Kalundborg; and Kalundborg Municipality (city hall).
In terms of energy cooperation, the Statoil refinery, Novo Nordisk and Novoenzymes purchase outgoing heat generated by electricity production. This enables a reduction of 240,000 tons of CO2 emissions per year. To decrease the strain on local water supply systems and to reduce costs, Kalundborg companies recycle and reuse nearly one-third of the 10 million m3 of water that they use annually.
As an example of byproduct reuse, the gypsum waste produced during desulfuration of flue gas at the Asnæs plant—some 150,000 tons per year—is used by Gyproc to manufacture gypsum board for the construction industry. Likewise, 150,000 tons of yeast, a waste product from insulin production at Novo Nordisk, is used each year in feed for 800,000 pigs. Moreover, the organic waste generated by Novo Nordisk and Novozymes is used in agricultural fertilizer. Also, some 30,000 tons of straw is converted into 5.4 million liters of ethanol.