The carbon dioxide generated by pulp mills is a valuable, largely untapped side stream that could be captured and used as a raw material for products replacing fossil-based materials and fuels as the technology and markets develop.

"Carbon capture offers Finland a major opportunity to build a new industry - and to undertake significant climate action, as the use of wood-based carbon dioxide reduces fossil raw material consumption and the related carbon dioxide emissions. It also promotes the EU's climate targets," says Kaija Pehu-Lehtonen, project director of Metsä Group's carbon capture project.

Metsä Group is a forerunner in capturing carbon dioxide generated by pulp mills. Its production units generate around 12 million tonnes of wood-based carbon dioxide annually, and the company is increasingly focusing on exploring its large-scale capture.

According to Pehu-Lehtonen, Metsä Group aims to develop its mills in accordance with the bioproduct mill concept. This means making ever greater use of pulp mill side streams to resource efficiently convert wood into increasingly valuable bioproducts. Harnessing carbon dioxide as a raw material is one example.

This autumn, Metsä Group and ANDRITZ, a technology company, completed their first survey examining what the capture of some four million tonnes of carbon dioxide from the flue gases of a mill the size of the Kemi bioproduct mill would mean in terms of technology and energy.

Carbon capture requires a great deal of heat energy. To account for this, the survey specifically explored ways to integrate carbon capture into the bioproduct mill as energy-efficiently as possible.

According to Pehu-Lehtonen, the survey demonstrated that it is possible to capture all the carbon dioxide generated by a large bioproduct mill but that it requires major investments and developments in the related technology and market before it can result in a profitable business.

"Twenty per cent of the heat energy required for carbon capture can be obtained from the bioproduct mill's current heat flows. New technological solutions are needed for the remainder," Pehu-Lehtonen explains.

Metsä Group is proceeding stage by stage in the carbon capture project and will pilot carbon capture next summer at the Rauma pulp mill with ANDRITZ. The pilot stage will be followed by plans for a potential demo plant.

If carbon capture proves viable, it will provide the forest industry with a new high-volume wood-based raw material giving rise to investments, workplaces and tax revenue - not to mention climate impacts.