In Denmark the major development in DH took place in the late 1950s and early 60s. After this and up to the late 80's. development was concentrated on consolidating and extending the positions of DH in the existing towns where DH is used. But this did not give rise to "new" districtheated towns as such.
In the last 5 years, however, there has again been progress in DH as no less than 55 towns have replaced their individual oilfired boilers with complete DH systems.
The 55 "new districtheated towns" have, on average, a size accommodating 4001,500 buildings, some have only about 100 buildings and others as many as 1,500 buildings.
How did DH succeed in achieving its high competitiveness in such small town communities where relatively few consumers must bear an investmentintensive, new form of supply?
The following explains this success:
Turnkey process
Planning process
Reform of financing form and method
High consumerconnection rate
Partial funding with grants.
To bring down construction costs, most new districtheated towns are based on a turnkey concept, where the new DH company buys in and provides all components, including the house installations and the sanitary and heating contraction work for both small and large consumers. Typically, a number of companies are suppliers to the DH company. However, the contracting is normally operated by one general contractor for each of the three main areas of work: production plant/building, distribution system, and house installations.
It is important for the new DH company that a turnover be created as quickly as possible to ensure coverage of interest commitments and depreciation of the investment. An important factor is therefore creation of the right management of the whole consumer connection process. Whereas consumers in large, existing DH towns make their own decisions as to when they want sanitary and heating work carried out, the kind of unit to be fitted, etc, planning in the "new DH towns" is tightly scheduled, street by street.
Consumer information is very extensive and there are strict requirements to attain coordination between connections to the branch pipes, removal of old boilers, fitting of new house installations, and opening for supply at streetsection level.
If construction works commence in April of any year, the main distribution network and production plant will normally be ready for operation in the first coming August.
In addition to the turnkey process the pattern of financing has been changed for the "new DH towns". The DH company call charge new consumers very limited connection tariffs.
A financing reform has been introduced which made a 100% financing of loans for DH installations possible. Also, it is possible to make a more convenient distribution of the interest and repayments burden. These indexlinked loans ensure uniform annual repayments in real prices.
The DH projects have nearly all been carried out with an initial consumerconnection rate of 7090% of the total potential. Moreover, the connection of all public buildings has been especially important, as these often represent relatively large energy consumption units.
In the first enterprises, the Danish Ministry of Energy has contributed with grants for a part of the construction works typically for a part of the piping network or the production station.
In the near future the number of CHP natural gasfired plants will increase. In the northern part of Jutland (4 counties) 20 new villages are expected to get CHP plants in 1991
-The district heating networks are laid out as 100% preinsulated steel or plastic pipelines or as a combination of both.
-In the normal types of houses a standard unit is fitted, either connected directly or in the form of a heat exchanger or a bypass system. Hot water is provided either by a hot water tank or a flow water heater.
Shown below is a representative heating price example for a DH consumer in a "new DH town", compared with the corresponding cost of individual oilfired heating in Germany and the United Kingdom.
It can be seen that the Danish price for DH in part as a result of plant optimisation Is highly competitive with foreign heating prices where the taxation level is lower than in Denmark.
The prices show the total heating costs. oilfiring in central heating installations comprises interest, depreciation, and maintenance of the oilfired boiler, whereas in DH the price is the consumer's tariff payable to the DH company.
When one takes into account that the DH company has paid for the DH consumer's house installation, the prices are comparable.
Terndrup is a small Danish town in northern Jutland. During 1992 a district heating heating supply was established based on straw burning and waste from slaghterhouses.
The main components of the supply system are a 4 MW strawfired boiler, a 400 m3 water accumulator tank, and a 6.3 MW peak and reserveload oilfired boiler. For storage of fat slaughterhouse waste two 100 m3 and a 10 m3 tanks have been installed. Also the straw is stored at the plant.
The mixing of fatty slurry with straw is an innovation in combination firing. The slurry a blend of water and organic fat Is a waste product from industries processing fatty products such as abattoirs. Approx. 45% slurry is added to the straw.
442 consumers have been connected to the DH network. The annual heat demand is expected to equal approx 21.000 MWh.
Sevel is a typical Danish village in the northern part of Jutland. Until 1993 a total of 200 buildings were equipped with either oilfired burners, stoves, or electric healing. During 1992 a DH supply was established for the whole town based on a natural gasfired combustion engine plant, which produces both heat and power.
The main components of the supply systems are a caterpillar gas engine with 1 MW electric power and 1.6MW heat output, a 230 m3 heat accumulator tank (water), and a 1.5MW peak and reserveload natural gas boiler. The annual electricity production will be 3200 MWh. the heat generation 4200 MWh a year, and the natural gas consumption 824,000 m3 a year.
The DH network is a lowtemperature district heating system made up of preinsulated steel medium pipes with a total length of 5 km.
More that 88% of all houses in Sevel are connected to the DH network. The expenditures for the users are 20% less than previously used oilbased heating, taking into consideration all types of costs.