The Danish city Kalundborg, situated on the west coast of Zealand, is an excellent
example of how industrial symbiosis – including district heating based on combined heat and power (CHP) production – results in large benefits for the environment. Among the benefits can be mentioned: recycling of by-products, reduced consumption of resources, reduced environmental impact, reduced discharges of wastewater and improved utilisation of the energy resources.

Industrial symbiosis
Symbiosis means “co-existence between diverse organisms in which each may benefit from the other”. In this context, the term is applied to the industrial co-operation
taking place in Kalundborg between a number of companies and the municipality of Kalundborg, all of which exploit each other’s residual or by-products mutually.
The symbiosis co-operation has developed spontaneously over a number of decades and today comprises some 20 projects. It is important to mention that all projects are environmentally and financially sustainable. 

Networking
The industrial symbiosis of Kalundborg is built as a network co-operation between six processing companies, one waste handling company and the municipality of Kalundborg.
The philosophy behind the symbiosis is that the six companies Energy E2 (owner of Asnæs CHP plant), the plasterboard factory BPB Gyproc A/S, the pharmaceutical
plant Novo Nordisk A/S, the enzyme producer Novozymes A/S, the oil refinery Statoil A/S, Soilrem A/S as well as the waste company Noveren I/S and the municipality of Kalundborg exploit each other’s residual or by-products on a commercial basis.
One company’s by-product becomes an important resource to one or several of the other companies. The outcome is a reduced consumption of resources and a significant reduction in unwanted environmental impact.
The collaborating partners also benefit financially from the co-operation as the individual agreement within the symbiosis is based on commercial principles.

Exchange of resources
Steam and heat
Asnæs CHP plant produces electricity for the national grid, district heating for the city of Kalundborg and process steam for the Statoil Refinery, Novo Nordisk A/S and for Novozymes A/S. The CHP production
results in a 30% improvement of fuel utilisation compared with a separate production of heat and power.
The design and construction of the district heating pipe network started back in 1980 with the purpose of reducing the overall energy consumption, and today approximately
4,500 households in Kalundborg are supplied with district heating from Asnæs CHP plant. District heating has replaced approx. 3,500 small oil-fired units.
Statoil Refinery receives process steam and water from Asnæs CHP plant. The steam covers about 15% of the refinery’s total consumption of steam. The refinery uses the steam for heating oil tanks, pipelines etc. Novozymes A/S and Novo Nordisk A/S use steam from Asnæs CHP plant for the heating and sterilisation of the processing plants.
Part of the cooling water from Asnæs CHP plant is used by a fish farm producing 200 tons of trout and salmon on an annual basis.
The fish have better growth conditions in the heated water.

Water
The Kalundborg region as well as the industrial companies are large consumers of water. This is why the symbiosis companies are seeking to recycle as much water as possible. Asnæs CHP plant has, for example, reduced its total water consumption by 60%. Previously Asnæs CHP plant used ground water for its power and heat production only. The ground water has now been substituted by surface water from the lake of Tissø and treated wastewater from Statoil. These efforts have enabled Asnæs CHP plant to reduce its ground water consumption by 90%. Earlier, Novozymes A/S also used ground water exclusively for processes requiring drinking water quality. 1 million m3 of ground water have now been substituted by lake water from Tissø from where water has been processed into drinking water quality by Kalundborg Municipality.
As the water from Tissø is not an unlimited resource, the consumption of lake water has gone down by 50%. Asnæs CHP plant has accomplished this reduction by recycling its own waste water.

Wastewater
The wastewater is led to a recycling reservoir
together with the runoff from the surrounding fields and surplus water from Tissø in the winter period. The recycling reservoir has a capacity of 220,000 m3 of water, which is used in the CHP plant processes.
The wastewater from Novozymes A/S and Novo Nordisk A/S is part of a genuinely
symbiotic relationship: Novozymes A/S treats all waste water up to a level corresponding to the wastewater of an ordinary household. From Novozymes A/S, the treated waste water is pumped to the treatment plant of Kalundborg municipality where a final treatment process takes place.
The Novozymes A/S waste water is of a relatively high temperature making it easier for the municipal treatment plant to treat its wastewater. In this collaboration process, the environment is also the winner as the overall discharge of nitrogen into the sea is very limited. Wastewater is also discharged from Asnæs CHP plant into the treatment plant of Kalundborg municipality.

Refinery gas
An “eternal” flare of surplus gas is part of the safety system in any refinery. Statoil’s refinery flare has been reduced to a mere night-light, because the refinery now exploits its own surplus gas internally. Formerly a large portion of the gas was transported by pipeline to BPB Gyproc and Asnæs CHP plant to be used in their production.

Gypsum
The desulphurisation plant of Asnæs CHP plant, which removes SO2 from the flue gas, produces about 200,000 tons of gypsum on an annual basis. Desulphurisation is a chemical process in which SO2 is removed while forming the by-product gypsum. The gypsum is sold to BPB Gyproc A/S, a company that manufactures plasterboard products for the construction industry. The gypsum from the CHP plant reduces the import of natural gypsum significantly.
Being more uniform and purer than natural gypsum, CHP plant gypsum is therefore well suited for the plasterboard production. Gypsum stemming from the municipal recycling station of Kalundborg is delivered to BPB Gyproc A/S, thereby contributing - on a smaller scale - to reducing imports of natural gypsum and the amounts of solid waste for landfilling.

Ash
Asnæs CHP plant removes fly ash from the flue gas while producing about 30,000 tons of fly ash on an annual basis. Ash deriving from orimulsion firing is recycled in a plant in Great Britain. Nickel and vanadium are reclaimed from this ash. The ash is recycled in the cement industry.

NovoGro®
Enzyme production at Novozymes A/S is based on fermentation of raw materials such as potato flour and cornstarch. The fermentation process generates about 150,000 m3 of solid biomass - the so-called NovoGro 30®. At the same time, 90,000 m3 of liquid biomass, NovoGro® is developed.
After inactivation and hygienisation, NovoGro® is used by some 600 West Zealand farmers as fertiliser in the fields, thereby reducing their need for commercial fertilisers. NovoGro® contains the by-products nitrogen, phosphorus and lime.

Yeast slurry
The insulin production of Novo Nordisk A/S also provides feed for pigs. The insulin production builds on a fermentation process where some of the main ingredients are sugar and salt, which are converted into insulin by adding yeast. After a heating process, the yeast - a residual product in this production - is converted into a much appreciated feed: yeast slurry. Sugar water and lactic acid bacteria are added to the yeast, making the product more attractive to pigs. Novo Nordisk’s yeast slurry replaces approx. 20% of the soy proteins in traditional feed mixes. Last year, over 800,000 pigs were fed on this product containing yeast slurry.

Liquid fertiliser
Statoil’s desulphurisation plant reduces the sulphur contents of the refinery gas whereby
SO2 emissions are reduced significantly. The by-product is ammoniumthiosulphate, which is used in the production of approx. 20,000 tons of liquid fertiliser, roughly corresponding to the annual Danish consumption.

Sludge
Sludge is a major residual product stemming
from the municipal water treatment plant in Kalundborg. The sludge is utilised at A/S Bioteknisk Jordrens Soilrem as a nutrient in the bio-remediation process. In this way, a waste product from one process is applied as a useful resource in another process.

Other waste
Noveren I/S collects waste from all symbiosis companies - waste that is an integral part of various processes. In return, the participating companies receive raw materials.
Noveren I/S produces electricity on the basis of landfill gas. This electricity is resold to power companies. In addition, Noveren I/S delivers a total of approx. 56,000 tons of combustible waste on an annual basis, corresponding to an energy consumption of approx. 6,500 private households in terms of power and district heating.

Advantages of the symbiosis
• The combustion of coal and orimulsion at Asnæs CHP plant results in approx. 80,000 tons of ash, which is used in the construction and cement industries for the manufacturing of cement or the extraction of nickel and vanadium.
• Every year BPB Gyproc A/S receives up to 200,000 tons of gypsum from Asnæs
CHP plant. This figure corresponds to the large majority of the company’s annual consumption. The gypsum substitutes the natural gypsum used in the production of plasterboards.
• NovoGro® from Novozymes A/S substitutes
the use of lime and part of the commercial fertiliser on approximately 20,000 hectares of farmland.
• The collaboration of Novozymes A/S, Asnæs Power Station and Kalundborg Municipality regarding wastewater treatment, reduces the environmental impact on the sea.
• The recycling of sludge stemming from the treatment plant brings about a reduction in production time at A/S Bio-teknisk Jordrens Soilrem, synonymous with expenditure cuts and improved economy.

On an annual basis, Noveren I/S receives:
• 13,000 tons of newspaper/cardboard which, after a quality check, is sold to cardboard and paper consuming industries in Denmark, Sweden and Germany producing new paper, new cardboard, egg boxes and trays for e.g. the health sector.
• 7,000 tons of rubble and concrete that are used for different surfaces after crushing and sorting.
• 15,000 tons of garden/park refuse delivered as soil amelioration in the area.
• 4,000 tons of bio-waste from households
and company canteens. The bio-waste is used in the compost and biogas production.
• 4,000 tons of iron and metal, which is resold after cleaning for recycling.
• 1,800 tons of glass and bottles that are sold to producers of new glass.

The exchange of resources between industrial companies provides a number of advantages:
• Recycling of by-products. The by-product of one company becomes an important resource of another company.
• Reduced consumption of resources, e.g. water, coal, oil, gypsum, fertiliser, etc.
• Reduced environmental strain: reduced CO2 and SO2 emissions, reduced dis-charges of wastewater and less pollution of watercourses etc.
• Improved utilisation of the energy resources. Waste gases are used in the energy production.

Conditions for a successful symbiosis
The philosophy behind the industrial symbiosis
can be used with advantage in other areas of industry. The Kalundborg experience,
however, demonstrates that a number of conditions must be fulfilled:

The companies must fit each other
An industrial symbiosis can only work given the right composition of industries in one area. One company’s residual products must take the place of another company’s raw material. Diversity within the local industrial structure is therefore a “must” in an industrial symbiosis.

The companies must be located near to each other
The physical distance between the individual companies is of great importance. The transport of residual products over large distances is seldom profitable which means that the distance must be as short as possible.
Experience from Kalundborg demonstrates that the geographical distance is the most important parameter when energy is exchanged between the companies. Other by-products can profitably be transported to advantage over larger distances.

There must be openness between the companies
Today the basis of the symbiosis co-operation of Kalundborg is openness, communication and mutual trust between the partners. The Kalundborg companies are located in a small community that has helped establish fine conditions for open and intimate working relations.
Summary
The industrial symbiosis co-operation in Kalundborg is unique in the world of today. Only the right composition of companies in a local area may provide the basis of sustainable projects. The more companies involved, the greater the opportunity for symbiosis, and consequently the potential for reducing resource consumption and environmental strain. In Kalundborg, the symbiosis has been built around a network of 8 partners. That explains why the industrial symbiosis has aroused international interest all over the world.

For further information about the industrial symbiosis projects, please contact:
The Kalundborg Centre for Industrial Symbiosis
Casa Danica Center
Hareskovvej 19
DK-4400 Kalundborg
Phone: +45 59 55 00 52
Fax: +45 59 51 22 55
E-mail: kalundborg@symbiosis.dk

VEKS
Att.. Lars Gullev
Roskildevej 175
PO Box 169
DK-2620 Albertslund
Phone +45 4366 0366
Fax +45 4366 0369
lg@veks.dk