Energy

Copenhagen, Denmark

97% of Copenhagen city heating supplied by waste heat

What is it?

The Copenhagen district heating system is one of the world's largest, oldest and most successful, supplying 97% of the City with clean, reliable and affordable heating. Set up by five Mayors in 1984, the system simply captures waste heat from electricity production - normally released into the sea – and channels it back through pipes into peoples' homes. The system cuts household bills by 1,400 EUR annually, and has saved Copenhagen district the equivalent of 203,000 tons of oilevery year - that's 665,000 tons CO2.

How does it work?

Waste heat, usually sent into the sea as a bi-product from four waste incineration plants and four Combined Heat and Power (CHP) plants, is pumped through a 1,300 km network of pipes straight into homes in several municipalities. 70% of the heat is sent to Copenhagen. The system maintains water temperature providing homes with cheap heat from a waste product.

To reduce greenhouse gas emissions, the CHP plants switched from coal to natural gas and biomass in the late 1990s. Moreover, a highly-efficient multi-fuel CHP unit was opened in 2001. The capacity of the unit is 570 MW power and 570 MW heat. With the annual use of up to 300,000 tons of wood pellets and 150,000 tons of straw, this CO2-neutral fuel covers up to 50 % of the total fuel consumption of the unit.

The price for district heating is highly competitive to other forms of energy. Annual costs per household are half that of oil, for example. Based on average consumption of 18.1 MWh/year per home (130 m2 in size), district heating is 11,342 DKK (1,500 EUR) compared to individual oil heating of 22.000 DKK (2,900 EUR). This is a saving of 10,658 DKK (1400 EURO).

Key results

• The district heating network covers 97% of the total heating needs of Copenhagen City- the equivalent of a floor area around 50 million square meters.
• The regional network provides 15% of the total Danish heat requirements.
• About 30% of the annual district heating demand is covered with surplus heat from waste incineration, and the remaining production of district heating is based on geothermal energy and fuels as wood pellets, straw, straw pellets, natural gas, oil and coal.
• About 80% of the CO2 emissions in Copenhagen result from the consumption of heat and electricity
• CO2 emissions have dropped by 187,600 tons annually from 3,460,000 tons in 1995 to 2,522,000 in 2000. Sulphur dioxide emissions have also been reduced by one third.
• In 2005 the entire district heating system replaced the equivalent of 290,000 tons of oil annually – that's 950,040 tons CO2e emissions avoided. Copenhagen represents 70% of the system, which equals 203,000 tons of oil or 665,000 tons CO2e emissions avoided.

Application

The Copenhagen example demonstrates that district heating is an extremely versatile, adaptable form of supply. It is incredibly flexible in terms of choice of production plant and the fuels used.

CHP technology is also well proven, with 12% of Europe's electricity generated from useable heat. By recovering the heat given off by electrical power plants that would otherwise be wasted, this technology could potentially be used to deliver heat directly to large individual end users, such as:

• large industrial pants
• oil refineries
• district heating networks to supply local communities.