Despite being located closer to the Swedish coast than to Denmark, Bornholm is a Danish island. Its inhabitants are proud of their Danish heritage, and of the 1658 rebellion in which the occupying Swedish force was overthrown and the Danish king was persuaded to take control once more.

Only 30km long, the island of Bornholm sits in the Baltic Sea 90km north of the Polish coast and 30km south of Sweden. Its northern rocky coast with its granite outcrops is in stark contrast to the fine white sandy beaches of the south, with a central forest area of mixed woodland both dividing and uniting the two. Bornholm’s inhabitants depend equally on fishing, agriculture and tourism for their livelihood.

Green Energy Plan

In any location, energy supply and consumption has considerable environmental impact and is potentially a major source of pollution. For an island which lacks its own indigenous supply of fossil fuel sources, these issues are magnified, particularly if one of the major sources of revenue on the island is tourism which relies on the beauty and cleanliness of the scenery.

Bornholm has long had a policy of reducing energy demand as far as possible. Its Green Energy Plan includes a number of energy saving schemes, such as the improved insulation of all buildings, calculated to reduce energy consumption by one third; the requirement to use low energy light bulbs by 2010; the installation of solar panels for domestic hot water; and the proposed construction of a photovoltaic power plant.

In the 1980s Bornholm declared a policy to use local energy resources wherever possible. These include solar, wind and waste. At present the majority of the island’s electricity (65%) comes via an under-sea cable which links Bornholm to the electricity supply network in nearby Sweden.

In its bid to support wind power, the Danish Government produced a detailed technical manual to enable ten local companies with no previous experience of wind turbines to construct the first windmills. That wind farm, inaugurated in 1987 north of the town of Hasle, is jointly owned by the municipality and the county council. Today the island boasts a number of mostly privately owned wind turbines. Typically these are private companies formed by a small co-operative of just 50-60 households. By the year 2010, a total capacity of 8MW from wind power is planned.

A straw-fired plant in Nexo, one of several, has been supplying district heating since 1989. There are plans for two further district heating plants in Hasle and Aakirkeby which will be fired by locally produced biomass.

Bornholm’s largest town, Ronne, is part-supplied with district heating by the nearby waste incineration plan run by Bofa, a joint venture public company formed in 1986 to co-ordinate waste management policy. Bofa also has the contract for waste collection on Bornholm, and manages the paper and glass sorting operations which process separately collected recyclable material.

Waste strategy

The main thrust of Bornholm’s waste policy is to reduce to a minimum material needing to be landfilled. Typically less than 1% of the island’s domestic waste goes to landfill. A proposed new landfill site next to the existing one, which is almost full, will provide 30-40 years of capacity, depending on diversion rates to other recovery and disposal routes.

Households have a weekly collection of ordinary refuse which they place in plastic sacks, and in addition a collection every four weeks of separated clean paper. Collection of bulky wastes such as old furniture is also provided and a specially fitted mobile collection point for hazardous materials such as chemicals, paints and solvents visits different towns on the island between two and four times a year, to a pre-arranged schedule. Householders also have six amenity sites to which they may deliver waste materials themselves. The site in Ronne, at the same location as the waste-to-energy plant, processes 40% of the total 3,000 tonnes of wastes which are delivered to such sites.

Glass recovery

Glass collection relies on strategically sited collection containers in public places, to which householders deliver their glass. Aluminium drinks cans are prohibited in Denmark and the majority of glass drinks containers carry a 1DKr deposit. These are mostly returned to retail outlets.

The island’s glass sorting plant recovers a very high proportion of whole bottles from the bottle banks. Each working day an estimated 500 whole green glass wine bottles are separated for re-use, while the same number of clear juice containers is collected every two weeks, and of clear glass drinks bottles (such as whisky bottles) every four weeks. Broken glass is shipped for reprocessing in Copenhagen on mainland Denmark. In 1994, 600,000 whole bottles were recovered, and 382 tonnes of mixed cullet sold for reprocessing.

Paper recycling

Seventeen thousand green waste paper bins have been distributed to householders in Bofa’s area. Since the objective is to optimise the collection of paper rather than to punish householders, trained collectors knock on the doors of households where waste paper bins are contaminated, to explain the requirements. To date only 10 paper bins have been withdrawn.

Bofa’s waste paper sorting plant has two feed lines for incoming material: one for clean and one for mixed paper. Four thousand tonnes a year of waste paper and cardboard are sent to Sweden for reprocessing. There has also been some use of shredded low grade waste paper for animal bedding on the island.This plant has been the focus of extensive testing for worker safety and the health implications of waste sorting procedures, and the plant is fitted with a number of special features. These include a sophisticated air filtration system employing bag filters. The areas where manual sorting takes place are under negative pressure to ensure clean air, and the staff rest areas are similarly protected.

Waste to energy plant

Waste management company Bofa is also responsible for the operation of the 50 tonnes per day Ronne waste-to-energy plant which has been operating since 1991. The Ronne plant supplies 6.2MW to the district heating system.Waste from 21,000 households (45,000 inhabitants) is delivered to the waste-to-energy plant, as well as additional wastes which result from the influx of around 400,000 tourists during the four month summer season each year. Bornholm has a wide range of hotels and bed and breakfast accommodation, and in addition around 3,000 privately owned summer homes. In 1994, the total input to the Ronne plant was 20,478 tonnes of waste from which 3,500 tonnes of ash and metal remained. Ferrous metal is recovered from the incoming waste and post-combustion from the ash.

Most of the health care wastes from the island’s only hospital are burned in the Ronne plant, with special precautions taken to protect the staff. These include the packaging of health care wastes into a special box, which is then placed manually into the crane and deposited directly into the furnace. As part of its management programme, Bofa ran training courses for hospital staff. In addition, a Bofa employee worked for two months at the hospital, advising on the sorting, handling and packaging of health care wastes destined for the waste-to-energy plant.


A European Union-funded battery collection scheme was started in 1987, using containers with four compartments. The resulting battery collections were poorly sorted, and it was clear that the four definitions of battery types was too complicated. Since 1989 the battery boxes, which are innovative pack-flat cardboard containers designed by Bornholm architect Jannik Stenberg, are divided into just two compartments. They are widely distributed in shops and supermarkets across the island, and carry simple instructions for correct sorting into two categories: those which are potentially environmentally harmful, and those which are not. The latter category are disposed of in controlled landfill on the island, reducing the high costs associated with shipping the potentially harmful types to appropriate off-island disposal facilities. Removal of the batteries from the waste stream assists in keeping emissions from the waste-to-energy plant at low levels.

Organic waste

A small trial of 100 households was undertaken recently at Bofa’s instigation to evaluate the effects of home composting. The resulting reduction in waste volume was 24%. No decision has yet been taken on the expansion of this scheme.

Plans for the future include a biogas plant which will process organic waste from households, hotels, restaurants and the food processing industry as well as from waste-water treatment plants and from farming. The biogas plant would generate electricity, heat and a fertiliser product for agricultural use. As yet funding has not been agreed for this independent project which would be a further step down Bornholm’s road to independence in energy supply.

Oil recovery

In a move to discourage the washing out of ships’ tanks and discharging oil and oily water mixtures into the ocean, Bornholm has introduced a rule which entitles every ship longer than 24 metres to free disposal for these wastes. An oil separation facility has been constructed alongside the waste-to-energy plant in Ronne. The facility attracts around 2,000 tonnes per year of oil and water mixture, typically in a ratio 45% oil to 55% water. Oil from private motorists as well as from commercial organisations such as garages is also accepted into the processing plant, which uses the reclaimed oil in the waste-to- energy plant’s after-burn chamber and discharges the water after cleaning it.

The future

A new rule requiring every Bornholm company to provide an annual report of its waste arisings was introduced towards the end of last year to help with planning for future waste disposal needs. There are also proposals to require everyone to join the district heating network.

Already Danish law has imposed a landfill tax of DKr195/tonne and a tax of DKr160/tonne for waste which is incinerated. Recycled wastes are tax free. These taxes are expected to increase to DKr285 for landfill, and DKr210 for production of hot water only (which is the output from the Ronne plant), while plants producing both electricity and hot water will stay at DKr160/tonne tax level. This is designed to maximise efficiency in Denmark’s mainland waste-to-energy plants.

These rulings may create some problems for Bofa at their Ronne incineration facility as such a small plant, with relatively tiny quantities of waste, could not efficiently generate electricity as well as feeding hot water to the district heating system. However, effective January 1997 a Danish ban on the landfilling of combustible materials is due to be introduced, with a ban on the landfilling of organics also under discussion. Bofa has ensured that Bornholm is already in a strong position to meet these requirements.


In 1996 the County of Bornholm established an International Department to coordinate their expertise and know-how with a view to exchanging information and experience with other islands and comparable regions. One important area of cooperation is energy and environment and the County invites our readers involved with similar projects to contact:
Jannik Stenberg, Architect MAA, senior expert Technical Department/International Department
County of Bornholm, Ullasvej 23
DK-3700 Ronne, Denmark
Tel: (Intl +45) 56 95 00 00
Fax: (Intl +45) 56 95 73 97

This article first appeared in the Warmer Bulletin, No 47, November 1995, published by the World Resource Foundation. We acknowledge their help in allowing us to reproduce the material.