The city of Sundsvall has a well-established district heating network. Hot water is distributed by Sundsvall Energi AB to private and commercial consumers by a 300 km pipe network. In 2006, heat from flue gas originating from steam production was recovered and delivered to the district heating network. In 2013 SCA and Sundsvall Energi AB built on their relationship with an initiative aiming at increasing delivery of hot water from SCA based on renewable energy, thereby reducing consumption of heating oil and emissions of carbon dioxide.
Prior to this investment, district heating was heavily dependent on fossil fuels. It had also become obvious that Sundsvall Energi AB needed to increase its capacity to ensure it met customer needs. The goal of the BioCoop project was thus to reduce consumption of heating oil and to offer district heating based on renewable sources, as well as avoiding a very costly investment to convert the Sundsvall Energy AB boiler from oil to biofuel. The capacity increase was achieved by:
a. Installing two new condensers and redesigning two of the existing boilers at Ortviken paper mill: Wood powder burners were installed, improved flue gas cleaning was achieved by complementing and upgrading the electrostatic precipitators and a plant for processing wood pellets into wood powder was built. The design capacity was 60 MW.
b. Utilising recovered secondary heat from SCA Östrand pulp mill with a new 10 km district heating pipe connected to Sundsvall Energi AB.
The two projects provide a potential reduction of CO2 emissions by 73,000 tonnes per year, of which 13,000 tonnes originate from replacing oil with wood pellets for internal steam production at the Ortviken paper mill.
Since the launch in 2014, in addition to the 100 GWh of recovered heat based on flue gas, 120 GWh per year based on renewable energy has been delivered by SCA Ortviken paper mill and SCA Östrand kraft pulp mill to the district heating network. Sundsvall Energi AB has reduced its emissions of fossil CO2 by approximately 35,000 tonnes per year. CO2 emissions by the Ortviken paper mill have been reduced by 15,000 tonnes per year, or 65%, compared to the years 2004 to 2013.