Das Fernheizkraftwerk Liestal in der Schweiz

In the early sixties a comparatively small heat plant was taken into operation in the public hospital of Liestal, a small town of 13 000 inhabitants in the Northwest of Switzerland. In subsequent years other public buildings were connected, and the plant's capacity, in several steps of expansion, almost trebled. The original »hospital heating« had become the nucleus of a small district heating system. A major event in the plant's history took place in 1992 when it was linked up with the cantonal refuse landfill site »Elbisgraben« only 2,5 km away. The utilization of landfill gas that is extracted from the Elbisgraben by means of a low-pressure pipe system is beneficial to the environment in two ways: Direct gas emissions to the atmosphere from the site of the refilse dump are substantially reduced, and at the same time it is possible to replace a considerable amount of fossil fuels. The landfill gas is burned in a specially constructed boiler that can be operated on either landfill gas or natural gas or on a mixture of both gas types. The operation mode of the boiler is adjusted to the changing quality of the landfill gas. The energy content of the landfill gas used in the Liestal district heating plant is equivalent to about two million litres of fuel oil per year and is expected to rise until the year 2000. In 1995 three block heat and power plants were installed and the landfill gas is now mainly utilised for simultaneous heat and power production. If the methane content of the landfill gas is too low it is burned, as before, in the special boiler. The three total energy units are then operated on natural gas (provided that the heat demand is sufficiently high). The Liestal district heating system is currently being expanded to the adjoining areas of two neighbouring municipalities and with the growing demand for heat and power the number of these total energy units will be increased to five. High priority is given to the protection of the environment. Special measures were taken for flue gas cleaning ; the amount of NO x in the flue gas is now limited to 70 mg/m 3 . The former Liestal »hospital heating« has been turned into a fully-grown heat and power plant that is now meeting the energy demand of a growing number of public and private consumers. It is a typical example of the cautious Swiss approach to district heating which is based on the opinion that this technology is only justified if the particular projects that are carried out are both economically viable and highly beneficial to the environment.