A highly evolved industrial symbiosis is located in the seaside industrial town of Kalundborg, Denmark (Gertler and Ehrenfeld 1996). Some 18 physical linkages comprise much of the tangible aspect of industrial symbiosis in Kalundborg (see Figure 27.2). The six key local players in the network that has developed are Asnaes Power Station, SK Power's 1350-megawatt power plant; a large oil refinery operated by Statoil A/S; Novo Nordisk Novozymes A/S, a Danish pharmaceutical and a Danish biotechnology company; Gyproc Nordic East, a plasterboard manufacturer; A-S Bioteknisk Jordrens, a
soil remediation company; and the municipality of Kalundborg. Several other users within the municipality trade and make use of waste streams and energy resources and turn by-products into raw materials. Firms outside the area also participate as recipients of by-product-to-raw-material exchanges. The symbioses evolved gradually (see Table 27.1) and without a grand design over the past 30 years, as the firms sought to make economic use of their by-products and to minimize the cost of compliance with new, ever-stricter environmental regulations.
At the heart of this system of arrangements is the Asnaes Power Station, the largest power plant in Denmark. Half of the Danish-owned power plant is fueled by coal and half by a new fuel called orimulsion, a bituminous product produced from Venezuelan tar sands. By exporting part of the formerly wasted energy, Asnaes has reduced the fraction of available energy directly discarded by about 80 per cent. Since 1981, the municipality of Kalundborg has eliminated the use of 3500 oil-fired residential furnaces by distributing heat from the power plant through a network of underground pipes. Homeowners pay for the piping, but receive cheap, reliable heat in return. The power plant also supplies cooling water that has been warmed 7-8 degrees in the process to supply an on-site fish farm producing about 200 tons of trout per year. Asnaes also delivers process steam to its neighbors, Novo Nordisk and Statoil. The Statoil refinery receives 15 per cent of its steam requirements while Novo Nordisk receives all of its steam requirements from Asnaes. The decision to rely completely on Asnaes for steam was made in 1982, when Novo Nordisk was faced with the need to upgrade and renovate its boilers. Buying steam from outside
Industrial symbiosis: the legacy of Kalundborg Table 27.1 Chronology of Kalundborg development
1959 Asnaes Power Station commissioned
1961 Statoil refinery commissioned; water piped from Lake Tiss0
1964 Original Novo Nordisk plant built
1972 Gyproc A/S built; excess gas piped from oil refinery
1973 Asnaes expands; draws water from Lake Tiss0 1976 Novo Nordisk begins shipping sludge to farmers 1979 Asnaes begins to sell fly ash to cement producers
1981 Municipality of Kalundborg completes district heating distribution network, using steam from Asnaes Power Station
1982 Asnaes delivers steam to Statoil and Novo Nordisk
1987 Statoil pipes cooling water to Asnaes for use as raw boiler feed water
1989 Fish production begins at Asnaes site, using waste heat in salt cooling water
1990 Statoil sells molten sulfur to Kemira in Jutland (ends 1992)
1991 Statoil sends treated waste water to Asnaes for utility use
1992 Statoil sends desulfurized waste gas to Asnaes; begins to use by-product to produce liquid fertilizer
1993 Asnaes completes flue gas desulfurization project and supplies gypsum to Gyproc 1995 Asnaes constructs re-use basin to capture water flows for internal use and to reduce dependency on Lake Tiss0 1997 Asnaes switches half its capacity from coal to orimulsion; begins to send out fly ash for vanadium/nickel recovery 1999 A/S Bioteknisk Jordrens uses sewage sludge from the municipality of Kalundborg as a bioremediation nutrient for contaminated soil was seen as a cheaper alternative. The two mile-long steam pipeline built for the interchange paid for itself in two years. In addition, thermal pollution of the nearby fjord from the former Asnaes discharge has been reduced.
The power station also provides a gypsum-containing feedstock to Gyproc Nordic East, a neighboring wallboard maker owned by the British company BPB plc. In 1993, Asnaes completed the installation of a $115 million sulfur dioxide scrubber that produces calcium sulfate, or industrial gypsum, as a by-product. Conveniently, gypsum is the primary ingredient of wallboard and Asnaes' scrubber became the primary supplier of Gyproc's gypsum needs. In anticipation of a year 2000 tax on carbon dioxide, Asnaes sought additional CO2 reduction and by 1998 had converted half of the plant from coal to orimulsion, described above. Achieving an 18 per cent CO2 reduction actually increased the sulfur content of the scrubber sludge so that 170 000 tons of gypsum is now produced per year. Consequently, Asnaes now has the capability to meet all of Gyproc's gypsum requirement. Formerly, Gyproc obtained gypsum from a scrubber at a similar German power plant and also from Spanish open-pit mines. Both could provide back-up sources in the event that they are needed for smooth operations. Some 70 000 tons of fly ash, the remains of coal-burning power generation, is sold by Asnaes for road building and cement production.
The Norwegian-owned Statoil refinery, producing a range of petroleum products from light gas to heavy fuel oil, is located across the road from Asnaes, from which it draws 80000 tons of steam. According to the environmental control officer (Ole Becher, personal communication 1998), the only by-product left from production of 4.8 million tons of crude oil per year is refinery gas which can be used internally or sold to Asnaes, once the sulfur is removed. In 1990, Statoil built a sour-gas desulfurization plant producing liquid sulfur that it shipped to a company for conversion to sulfuric acid. Today, about 20000 tons of liquid fertilizer are manufactured from ammonia thiosulfate, which is a major by-product of Statoil's flue gas removal system, while the excess gas is burned at Asnaes. In 1972, Statoil began piping butane gas to Gyproc to fire wallboard drying ovens, all but eliminating the common practice of flaring waste gases. This system is now used as a back-up to public pipeline supply.
Groundwater scarcity in Kalundborg is generally claimed to be the motive force that brought many of the partners together (J. Christensen, personal communication 1998). In the early 1960s, need for surface water led to a Statoil project to bring supplies from Lake Tiss0, some 50 kilometers from Kalundborg. Asnaes and Novo-Nordisk later joined the project as well. In addition, there are many other water and wastewater re-use schemes. Since 1987, Statoil has piped 700000 cubic meters per year of cooling water to Asnaes, where it is purified and used as boiler feed water. Statoil has also made treated waste water available to Asnaes, which uses about 200 000 cubic meters a year for cleaning purposes. Statoil's investment in a biological treatment facility produces an effluent sufficiently clean for Asnaes' use. Symbiotic linkages have reduced total water consumption by participating companies by around 25 per cent and, at the power station, by 60 per cent.
A few kilometers from Asnaes and Statoil is Novo Nordisk, a world leader in the production of insulin and enzymes. The plant employs more than 1000 people. Novo Nordisk makes its product mix by fermentation, based on agricultural crops that are converted to valuable products by microorganisms. A nutrient-rich sludge remains after the products are harvested. Since 1976, Novo Nordisk has been distributing the process sludge to about a thousand nearby farms where it is spread on the land as fertilizer. After heat treatment to kill remaining microorganisms, the sludge is distributed throughout the countryside by a network of pipelines and tanker trucks. Novo Nordisk produces 3000 cubic meters of sludge per day, but can only store three day's worth. The sludge is given away instead of sold, reflecting the firm's concerns for disposal security. Three full-time employees coordinate its delivery. Distributing the sludge as fertilizer was the least-cost way to comply with regulations prohibiting Novo Nordisk from discharging the sludge directly into the sea. In addition, surplus yeast from Novo Nordisk's insulin production is sold as a high-value animal feed. Savings from more efficient utilization of resources and elimination of wastes are shown in Table 27.2.
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