As dealt with in the First chapters of this book, flexibility, diversification of the use of energy, and protection of our environment are some of the key issues of Danish district heating (DH).
In this chapter three concrete case studies have been selected in order to illustrate various aspects of DH:
The first example represents very large integrated DH systems in this case the Copenhagen system. This system Involves all of Copenhagen and a large part of Its suburbs. serving a population of approx. 250,000 households. The Individual DH systems. which date back to 1893 are integrated in a regional heat transmission network. The main supplier of heat energy to this system is a number of new and older combined heat and power (CHP) plants plus some local waste incinerators.
The second case Is typical for middlesize towns. Haderslev has had a DH network for approx. 30 years. In contrast to the systems of the large cities, this plant is privately owned by its consumers. From the beginning heat was supplied by oilfired stations, but a waste incinerator had also been added In 1966. In 1984 oil was replaced by natural gas. In order to obtain the maximum use of local resources, the DH company, local power company, and waste collection company of the region entered into an agreement to build and operate a socalled decentral CHP plant based on burning local household refuse from Haderslev and its surroundings. This station is soon expected to produce 6570% of the heat energy demanded in Haderslev.
Plans have also been made to install a natural gasfired CHP plant to cover additionally about 25% of the heat demand. Thus 9095% of the heat demand of Haderslev can be covered by surplus heat from power production from 1996.
The third case represents the very small communities, where there is a large potential for utilising local biofuels from the surrounding countryside (e.g. the town Terndrup, see figure) and CHP fired by natural gas (e.g. the village Sevel, see figure).
During the past few years many new DH systems have been established in smaller towns with 2001000 buildings. The existing individual oil burners have been replaced by a new DH system where the heat production is based on local biofuels or natural gasBred CHP on a gas motor. Within the next few years several more DH towns using natural gasBred CHP are expected to be established.