Brief
In the Danish city of Silkeborg, with just about 50,000 inhabitants, the world’s largest solar district heating plant was installed in 2016. It is the outcome of an ongoing process since 2014, when both economic and environmental reasons pushed the district heating company to seek carbon neutral alternatives such as solar thermal. Silkeborg’s objective is to produce carbon neutral heat by 2030.
Technology
The 12,436 flat plate collectors are installed on agricultural areas in front of the city’s gate, covering a total area of 156,694m². This solar thermal installation delivers 80,000 MWh of energy to 22,000 households every year and has a solar thermal capacity of 110 MWth. It covers 20% of the heat demand in the district heating network of Silkeborg during spring, autumn and winter, and the complete heat supply during the summer. Each year, 15,000 tonnes of carbon emissions are avoided thanks to this solar district heating plant.
The plant does not include seasonal thermal energy storage, despite its dimensions. This results in particularly low heat costs and is facilitated by the size of the city of Silkeborg, which has a high enough summer load to utilize all the solar heat directly when produced.
Next to solar thermal energy, electric boilers and waste heat recovery are supplying Silkeborg with 42% of the town’s heat demand. To reach climate neutrality by 2030, the district heating network will soon be powered also by electric heat pumps and a biomass boiler with wood chips generated from gardens and park’s waste. Both of these additions are planned for 2025.
