A rock chamber of 50,000 cubic meter was created in central Stockholm in 2010 for the storage of cold water, with the aim to reduce the peak load on energy production. The plant has helped to reduce carbon dioxide emissions by approximately 30,000 tonnes per year.
This underground storage is a part of the district cooling network in Stockholm. The large volume of 50,000 cubic meter allows for what is known as 24-hour storage, where cooling can be topped up during the night so that it can meet day-time needs. Storing cooling over the 24-hour period is not a new technology. However, laying the whole system below ground level is unusual and makes it possible to raise the capacity of the district cooling network even in densely populated areas.
The project is a good example of how smart energy distribution can lead to substantial improvements in efficiency:
• Electricity consumption can be reduced by 25 GWh per year at full capacity.
• The need for conventional cooling can be reduced by around 15 MW per year at full capacity.
The rising temperatures will lead to a large demand for energy for decreasing air temperature and dehumidifying the air. District cooling can be an efficient solution to meet this demand during higher temperatures and can offer an energy-efficient and environmentally sound alternative to traditional cooling plants.