District cooling
District cooling , like district heating , is the supply of a consumer with cooling via a long-distance pipeline. As with district heating, thermal energy is transported, but in the opposite direction. There are different methods for doing this.
Delivery of cold water
Here, water is cooled in a central refrigeration unit and delivered to the consumer via a temperature-insulated pipe network. A flow temperature of around 6 ° C is provided for this purpose. Heat is dissipated from the consumer, for example for air conditioning. The return temperature is therefore higher than the flow temperature, around 12 ° C and more. This excess heat is withdrawn again in the refrigeration center via refrigeration systems. The main component of the refrigeration systems are chillers .
Use of district heating
In many areas supplied with district heating , absorption refrigeration machines are operated with the aid of district heating in facilities with high cooling requirements . As in winter, hot water is supplied to the customer and cooling is only generated on site. This makes sense because electrically operated air conditioning systems require high performance, especially at peak load times. By using absorption chillers, district heating networks can be used to a greater extent in the warmer seasons. At the same time, the load on the power grid can be relieved on these warm days, since less electricity-driven cooling machines are required.
Application examples
In the Swedish city of Sundsvall , the hospital is supplied with district cooling in summer. There, snow is stored in a 50,000 cubic meter basin , which is covered with tree bark. The melt water cools the hospital's district heating system via a heat exchanger. This system works like this, but not more cost-effectively than air conditioning.
The Deep Lake Water Cooling System is a project that uses the cold stored in the water of Lake Ontario to supply various buildings in Toronto with environmentally friendly cold for cooling.
Chemnitz (then Karl-Marx-Stadt) has been the second German city to have a district cooling network since 1973 . The approximately four-kilometer-long network operated by Stadtwerke Chemnitz supplies the technical university , opera house , town hall , district court and several large shopping centers. Initially, the cold was generated using compression refrigeration machines. At the beginning of the 1990s, modernization followed by installing absorption chillers . Since the end of June 2007, a cold storage tank with a capacity of 3500 m³ has been ensuring optimal operation of the cold generator as well as covering peak loads on midsummer days. This makes it possible to largely dispense with the refrigeration machines driven by electrical energy. The absorption chillers are operated with the waste heat from the thermal power station, which would otherwise be released into the environment via cooling towers.
In 1998 the Fraunhofer Institute for Environmental, Safety and Energy Technology in Gera started a pilot project in which a steam jet cooling machine, which is driven by the steam from the local district heating network, supplies a district cooling network with cold water at 6 ° C in the city center. Such chillers have only been used in industrial production so far. A compression refrigeration machine can be switched on at peak load times. Both machines provide 600 kW each, i.e. a total of 1.2 MW cooling capacity.
In 2012, a district cooling system was installed in Munich on the western Stadtgrabenbach in the basement of the Stachus . District cooling is used, among other things, to air-condition the Hofstatt shopping center . In 2017, Munich's inner city network was a good 14 kilometers long to supply almost 30 retail, residential and office buildings with a cooling capacity of 12 megawatts. There is a further expansion, especially between Odeonsplatz and the valley. A second cooling center is under construction under Herzogspitalstrasse. In January 2017, work began on a third underground district cooling system at Odeonsplatz.
In Vienna , cold is generated from the waste heat from some power plants and a waste incineration plant and distributed via a district cooling network using the principle of absorption refrigeration machines. In 2017, the cooling capacity was 20 megawatts.
In Paris , the water from the Seine is used to cool the district cooling network.
Web links
- District cooling network in Helsinki / Finland
- TU Chemnitz: Feasibility study for the use of cold storage
Individual evidence
- ↑ REINHARD WOLFF: District cooling with snow . In: The daily newspaper: taz . July 22, 2006, ISSN 0931-9085 , p. 7 ( taz.de [accessed on January 27, 2018]).
- ↑ Gregor Honsel: Chemnitz energy saving project: Cold from the giant thermos . In: Spiegel Online . June 15, 2007 ( spiegel.de [accessed January 27, 2018]).
- ↑ District cooling in Gera
- ^ State capital Munich: Annual report on urban policy 2012 , page 74
- ↑ Dr. Florian Bieberbach: Munich's climate-friendly cooling supply. In: press release. Stadtwerke München GmbH, May 12, 2017, accessed on September 1, 2017 .
- ↑ District cooling | Power generation | Energy supply | About us | Wien Energie . In: www.wienenergie.at . ( wienenergie.at [accessed on January 27, 2018]).
- ↑ District cooling has been cooling for ten years - wien.ORF.at. Retrieved September 1, 2017 .
- ↑ District cooling at the main station | District cooling main station | Energy | Innovation | Smart City | Wiener Stadtwerke . In: www.wienerstadtwerke.at . ( wienerstadtwerke.at [accessed on September 1, 2017]).
- ^ Cooling and heating networks for the low-carbon city. ENGIE, accessed February 9, 2018 .