Heat produced by the sun is recovered with district cooling.
Helen’s district cooling system is used for recovering heat produced by the sun, machines, appliances and people in homes, offices and shopping centres in Helsinki. In the summer season, cooling is primarily produced with the world’s largest heating and cooling plant of its kind and with huge cooling energy storage facilities.
With district cooling, surplus solar heat in a property can be processed for utilisation and transmitted further into the district heating network.
- For example, last summer we used district cooling to produce an amount of renewable district heat that would otherwise need 22 hectares of solar collectors. In the summer, renewable district heat mainly comes from solar energy, tells Kosti Koski, manager of the district cooling business at Helen. On the hottest days of the summer, it is possible to recover up to 800,000 kWh of renewable district heat a day with district cooling. This corresponds to the daily need for hot tap water of 250,000 Helsinki residents.
The district cooling network in Helsinki already covers the city centre and is expanding to new areas each year. An extensive district cooling system is being built in new districts, such as Jätkäsaari and Kalasatama, in connection with the construction of the conventional infrastructure.
The district cooling system in Helsinki is the third largest in Europe, and it is the most rapidly growing cooling system in Europe.
World’s largest heating and cooling plant in Helsinki
The majority, over 60%, of district cooling in Helsinki is produced in the world’s largest heat pump plant of its kind, producing district heat and district cooling. The plant is located in a rock cavern excavated under the Katri Vala Park in the district of Sörnäinen in Helsinki.
The heating and cooling plant has been prepared for the hot days of this summer by undergoing basic maintenance. At the Katri Vala plant, district cooling is produced with industrial-scale heat pump technology. Heat is recovered from the return water of district cooling and from waste water purified in Viikki. The district heat processed from the waste heat that is collected by the district heating system of the Katri Vala heating and cooling plant is sufficient in the summer to meet most of the heating need in the centre of Helsinki.
District cooling is also produced at Salmisaari which uses the absorption cooling technology and, in the winter, cold sea water to produce cooling.
The need for district cooling varies according to the weather conditions in the summer. Production and demand elasticity is balanced with gigantic chilled water storage under the Esplanade Park and the district of Pasila. The chilled water stays cool throughout the year in these underground water storage facilities.
• Output of the Katri Vala heating and cooling plant: 60 megawatts of district cooling and 90 megawatts of district heat concurrently.
• On a hot summer’s day, half of the district heat in the entire city of Helsinki is based on surplus heat processed for utilisation in the Katri Vala heating and cooling plant.
• Elasticity of demand and production in district cooling is balanced with chilled water storages. The size of the underground storage in Pasila is 11 million litres and the one under the Esplanade Park is 38 million litres.