What is it?

The Copenhagen district heating system is a heating supply system that uses waste heat from refuse incineration plants, and combined heat and power plants (CHPs). The process saves energy and substantially reduces CO2 emissions and pollutants.

How does it work?

Waste heat, usually sent into the sea as a byproduct from the incineration plants and Combined Heat and Power plants (CHPs), is pumped through a 1,300 km network of pipes straight into homes. The system maintains water temperature providing homes with cheap heat from a waste product.

In 1984, five Mayors (Copehagen, Frederiks-berg, Gentofte, Gladsaxe and Taarnby) decided to set up on common district heating system that would provide affordable and clean heating to municipal homes in their regions. To do this they set up a partnership with the Metropolitan Copenhagen Heating Transmission (CTR) which runs the system in partnership with an affiliated company in the west of the city, known as VEKS. The network now heats a number of municipalities – Copenhagen takes 70% of its total heat.

The CTR and VEKS system connects four CHP power plants, four waste incinerators and more than 50 peak load boiler plants with more than 20 distribution companies in one large pool-operated system, with a total heat production of around 30,000 Terra Joules.

A number of key factors have made this system successful, including:

Clean power

The reduction in CO2 emissions from 1995 to 2000 is mainly due to the fact that the CHP plants switched from coal to natural gas and bio fuels, such as straw and wood pillars. CTR & VEKS purchases 70% of its district heating from large sustainable CHPs in the Greater Copenhagen area, including the state-of-the-art Avedoere unit 2, began operation in 2001. This unit is one of the most energy efficient and environment friendly units in the world and utilizes up to 94 % of the fuel energy. The capacity of the unit is 570 MW power and 570 MW heat. The unit is called a multi-fuel unit, because it can use several kinds of fuels - wood pellets, oil, natural gas and straw. 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.

Other sustainable CHPs sources used by the system include; Amagerværket, Svanemølleværket and H.C. Ørsted Værket. These were the first to receive international environmental ISO 14001 accreditation – requiring power stations to make ongoing environmental improvements. As a result they introduced DeNOx system, which remove nitrogen oxide from fuel gas, and are also equipped with desulphurization technology.

30% of the heat supply is produced by refuse incineration plants and the remaining requirement is met by oil-fired heating plants.

Tax Incentives

In the mid-1980s the Federal Government introduced tax incentives on fuel for electricity plants. They paid less fuel tax if they used CHP (in some cases this amount equated to less than 50% tax incentive). This enabled the companies to sell heat to consumers at a lower price.

Planning regulations

Another important incentive was amendments to planning regulations. In 1979, a new heat supply act was implemented which started a heat planning process in the municipalities – this enabled municipalities to dedicate a certain area to district heating, and make it mandatory for households to connect to district heating. As a result, take up rates have increased to almost 100%. While consumer choice was removed, costs to consumers were reduced.

Price

The price for district heating is highly competitive to other forms of energy. CTR's heating price, which is a pool system price, is identical for all five municipalities, and has basically been kept at the same level throughout the whole of the project's lifetime. 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).

Computer based monitoring system

The system is managed through CTR's operations centre in Frederiksberg, using computer-based control, regulating and monitoring systems. The two networks, CTR and VEKS are interconnected so that excess heat and/or reserve capacity in the one area can be utilized by the other. As a result the district heating system is extremely reliable.
Results

* Today the district heating network covers 97% of the total heating needs of the Copenhagen City- the equivalent of a floor area around 50 million square meters.
* The CTR and VEKS network also 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.

Under the Copenhagen system, transmission companies supplying energy can choose freely among the various production plants due to the integrated structure of the system. The choice is based on which production plant:

* is the cheapest to take into operation
* the most suitable to cope with the environmental directives prescribed by government

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.

The introduction of the new heat supply act in 1979 was also important because it brought together a number of municipalities - all differing in size and political views - to set up one common heating system. The central authorities issued guidelines, supervised the planning and approved plans, while municipalities did the planning in collaboration with energy utilities and consultants.