With a water-filled rock chamber beneath Kungsholmen in Stockholm, the energy company Stockholm Exergi has been able to substantially increase capacity in the city’s network for district cooling. The ordinary cooling plants in buildings can be phased out, and both high electricity needs and the risk of leakage of ozone-depleting substances will decrease along with them.
Traditional cooling machines are heavy consumers of electricity and may also, for example, contain freons. District cooling, which works like district heating but in reverse, is a good alternative. The energy company Stockholm Exergi, with support from the climate investment programme Klimp, has raised the capacity of the district cooling network by constructing a water-filled rock storage chamber beneath Hornsberg in Stockholm. The storage chamber was commissioned during the summer of 2009 and has made it possible to phase out cooling machines from the connected properties. The project is a good example of how smart energy distribution can lead to substantial improvements in efficiency:
• At full capacity, electricity consumption can be reduced by 25 GWh per year.
• Cooling machines with a combined output of more than 80 000 kW can be switched off.
• Reduction in greenhouse gas emissions of 14,000 tonnes of CO2 per year.
• Very low leakage of ozone-depleting refrigerants (r134a).
• Reduced noise when cooling plants are removed.
Why best practice: Positive environmental and economic impacts
There is a great global need for energy to cool buildings, including in countries in the temperate region. Energy-saving technical system solutions such as remote cooling offer great potential in many countries. District cooling can offer an energy-efficient and environmentally sound alternative to traditional cooling plants. The project has shown through its unique 24-hour storage that the capacity in a district cooling network can be substantially raised. Placing the installation in a rock chamber makes it possible to build stores within built-up areas. The results of the project indicate that there are good prospects of disseminating the technique to other places with extensive needs for district cooling. Stockholm Exergi anticipates that continued connection to the district cooling network will reduce the need for conventional cooling plants by around 10 MW per year.
The rising temperatures need a large demand for energy for decreasing air temperature and dehumidifying the air. District cooling can be an efficient solution to meet this larger energy during higher temperatures. Furthermore, district cooling makes the existing cooling system, such as refrigerators, more energy-efficient which reduces CO2 significantly. The project presented here is focusing the case in Kungsholmen.