Co-creating a shift from coal to renewables at Gratkorn Mill

The recently modernised multi-fuel boiler at Gratkorn Mill is now fuelled by biomass and natural gas. The goal is to finally use only renewable and clean energy.

The world needs urgent action to limit climate change. At Sappi we’re doing our part by decarbonising our global business in our mills like in Gratkorn in Austria, our largest production site in Europe. “Our path to decarbonisation at Gratkorn requires marshalling the expertise and ingenuity of our people and partners like never before”, says Max Oberhumer, Mill Director. "Boiler 11 is the latest proof of our promise, with an investment of EUR 35 million that will reduce our carbon footprint by almost 30 per cent."

Producing pulp and paper is an energy-intensive process that historically at Gratkorn Mill was partially dependent on coal, explains Power Plant Manager, Anton Mercina. Coal that the world is now working to shift away from to limit climate change. Using state-of-the-art technology, the recently modernised coal boiler at Gratkorn is now fuelled by biomass and natural gas. The goal is to finally use only renewable and clean energy. This transition will also make us more energy independent during these uncertain times in the energy market.

Sappi mills across Europe, North America and Southern Africa are equally ambitious on our global decarbonisation journey. No matter the location, we #CoCreate solutions by bringing together the brilliance of technology, the power of nature and the creativity of people.

Decarbonising with biomass 

Gratkorn’s biomass inputs come from different residual sources, from the wood we use to make pulp to black liquor, a valuable residue from the pulping process. In the future, we’ll also use other residues from the forest management process and forest industry value chain. Forest biomass is a source of renewable energy. Trees absorb carbon while they grow, and harvested forest products continue to store that carbon. With responsible forest management practices, new trees grow post-harvest and so the carbon cycle continues to flow.  

While burning woody biomass releases biogenic carbon into the atmosphere, it provides an essential substitute for fossil-derived fuels and emissions. When residual biomass sources like black liquor and tree branches are used for energy, it also enables more value to be derived from each tree harvested.   

Co-engineering the future 

Modernising an existing boiler is a major undertaking. At Gratkorn Mill, it was a three-year project. Construction started in August 2021 after pre-feasibility planning and engineering of the re-build. We began by dismantling the old boiler parts and then installing all the new state-of-the-art equipment. Commissioning began in June 2022 before full start-up in September.  

“At peak times the project involved over 200 people with Sappi teams and partners joining their expertise to realise this complex and ambitious project”, explains Project Manager, Christian Roth. Two of those partners were Siemens Energy whose process control technology made the system even more resource efficient, and Sumitomo Heavy Industries OY as a technology provider. Because of innovative partnerships like these, we were able to realise other benefits beyond decarbonisation such as improved air quality in and around the mill.  

Brilliantly co-creating 

The transition from coal to biomass at Boiler 11 isn’t an overnight process. It has required a lot of adaptation, just as in nature. And all the diversity seen in nature too. “Our team for this project was a brilliant mix of talent and expertise across engineering disciplines”, says Helene Kindermann, a mechanical engineer at Gratkorn Mill. “Together, we truly co-created this solution.”  

There was a complexity to this project that’s probably hard for most to appreciate, she says. For instance, the team refurbished 300 valves during the construction phase. Organising all the components that are necessary for this work – spare parts, workers, tools, scaffolding, insulation and even cranes – took a true team effort. The progress Gratkorn Mill has achieved has inspired us all at Sappi to push ambitiously ahead and not shy away from the complex projects that help future-proof our mills in the face of climate change. It also shows that the green energy transition isn’t in some distant future. It’s happening in the here and now at Sappi worldwide.