Without careful analysis, it may seem that the effect of Kalundborg is to lock in old technologies in a situation of mutual dependence. The facts do not bear this out, but rather establish Kalundborg as a dynamic and adaptive system. Some trades have come and gone, such as Statoil's sulfuric acid production; some never got off the ground, such as greenhouses powered by Asnaes steam; and new ones are constantly being evaluated.
A new partner, A/S Bioteknisk Jordrens, joined the symbiosis in 1999. The company uses municipal sewage sludge as a nutrient in a bioremediation process to decompose pollutants in contaminated soils. This has allowed for beneficial re-use of another
Industrial symbiosis: the legacy of Kalundborg Table 27.2 Waste and resource savings at Kalundborg
Annual resource savings through interchanges
Statoil: 1.2 million cubic meters Asnaes: total consumption reduction 60% Fuel savings
Asnaes: 30000 tons of fossil fuel by using Statoil fuel gas community heating via steam from Asnaes Input chemicals/products fertilizer equivalent to Novo Nordisk sludge (about 1300 tons nitrogen and 550 tons phosphorus)
97000 cubic meters of solid biomass (NovoGro 30)
280 000 cubic meters of liquid biomass (NovoGro)
commercial fertilizers for 20000 hectares of farmland using Statoil sulfur
170 000 tons of gypsum recovered vanadium and nickel
Wastes avoided through interchanges
50000-70000 tons of fly ash from Asnaes scrubber sludge from Asnaes
2800 tons of sulfur as hydrogen sulfide in flue gas from Statoil (air) water treatment sludge from Novo Nordisk (landfill or sea) 380tons of sulfur dioxide avoided by replacing coal and oil (air) 130 000 tons of carbon dioxide avoided by replacing coal and oil (air)
material stream drawn from the city's waste water. Currently, some symbiosis partners are looking at other surface water sources to enable savings of groundwater and to offer alternatives at low flow times. The partners are also looking at water re-use broadly through the establishment of common water basins. The Asnaes Power Station recently added a 250 000 cubic meter basin to improve water flow management.
The change at the power plant from coal to orimulsion has brought other trading opportunities by changing the effluent streams. The sulfur content in orimulsion is 2.5 per cent, versus 1 per cent for coal, so significantly more calcium sulfate is recovered from the flue gas desulfurization system and is available for raw material to make gypsum board. While the opportunity to close down older coal units has beneficial effects, orimulsion is not harmless. In fact, the fly ash has a significant heavy metal content with a concentration of 5 per cent nickel and 10-15 per cent vanadium. In addition to worker safety issues, two new exchanges have entered the symbiosis: the recovery and re-use of nickel and vanadium from the generator's ash stream.
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