Perhaps the best and the most widely cited example of the by-product exchange strategy of industrial ecology is the exchange network that evolved spontaneously in Kalundborg, Denmark. These exchanges of materials and energy between industrial firms, the community, and farmers began in the late 70s and have generated a significant return on investment and environmental benefits.
The 1500 MW Asnaes power plant supplies the power and heating needs of the area. Generating electricity from coal is at best 40 percent efficient so Asnaes distributes its excess heat to nearly all of the towns 5,000 homes. This is equivalent to 225,000 tons of steam per year, reducing the towns oil consumption by 19,000 tons per year. The excess heat also goes to the Asnaes fish farm which produces 250 tons of fish yearly. The sludge from the fishponds is sold by Asnaes as fertilizer.
Statoil, a nearby large oil refinery uses excess steam from Asnaes to cover 40 percent of its heating requirements. Novo Nordisk, which manufactures pharmaceuticals and enzymes also uses excess steam from Asnaes to cover all its heating and processing needs. Novo Nordisk saves US$ 1M annually because of lower energy costs. A three-kilometer pipe links the three firms.
Asnaes has a $115 million sulfur dioxide scrubber which produces industrial gypsum (calcium sulfate). It sells this gypsum to its neighbor Gyproc, which manufactures wallboards. Two thirds of Gyprocs needs come from Asnaes.
Asnaes also sells 200,000 tons of fly ash and clinker for use in building roads and producing cement, thus it needs no landfill for these wastes. Similarly, Statoil supplies Gyproc with ethane and methane to fuel the ovens that dry its wallboards. Statoil also supplies flare gas to Asnaes to use in its boilers. This created savings and reduced carbon dioxide emissions. Statoils desulfurization stage produces sulfur that it sells to Kemira, a sulfuric acid producer.
Statoil pipes cooling water to Asnaes which uses it as a boiler feedwater. It also sends 200,000 cubic meters of wastewater to Asnaes for cleaning industrial equipment. This reduced thermal pollution in the nearby fjord and lessened water demand from the industries by 25 percent.
Novo Nordisk distributes for free to thousands of neighboring farmers the nutrient-rich sludge from its pharmaceutical operations. Novo uses the steam from Asnaes to heat the sludge and kill the microorganisms.
The Kalundborg industrial ecosystem is the ideal setting of industrial symbiosis, thus far. It is economically viable, the raw material is cheaper than virgin materials, and it is an inexpensive way of complying with environmental regulations.
© 2000 Prime Project M2:IE