Fortum's joint venture Stockholm Exergi will close its last coal-fired boiler for electricity and heat production at the Värtaverket power plant in Stockholm at the end of the heating season in the spring of 2020. The closure will take place two years earlier than originally planned.

In 2016, Stockholm Exergi replaced most of Värtavärket's old coal-based production with biofuels. The company is now investigating whether a carbon capture system (CCS) could be utilised at the plant, which would render the plant carbon negative. Based on the pilot in progress, bio-CCS is also a cost-effective alternative for reducing carbon dioxide emissions. The captured carbon dioxide can be stored permanently, for example, in seabed rock formations, utilised in industrial processes or used in greenhouses.

Fortum is also testing CCS technology in Oslo at its joint venture Fortum Oslo Varme. Both the Stockholm and Oslo projects are partnering with the Northern Lights initiative, which is studying carbon storage in the bedrock of the North Sea.