Biogenic carbon sequestration - materials and processes

Industry and society face major challenges in the transformation to become fossil-free when renewable and recycled materials and products replace fossil fuels. An ambitious transition is needed to reach the climate goals in line with what science says is required to limit global warming to 1.5˚C. A large part of the work consists of reducing emissions as much as possible and, in parallel, increasing the amount of biogenic carbon built into materials and processes. Different materials and processes contribute to varying degrees of permanence of the carbon sink. The choice of biogenic carbon sink affects the surrounding ecosystem in different ways and they are associated with different costs per CO2 equivalent. Several methods are already used, such as wooden construction, while some have only just begun to be developed in Sweden, such as biochar supplied to forest plants.

Interest in timber based buildings has increased rapidly in Sweden and internationally. A lifespan of at least 100 years is often a  requirement in the planning process and in Sweden there are many examples of wooden buildings that are significantly older than that. The Government also intends to promote increased timber construction to reduce climate impact and vulnerability, through reliable raw material supply from several suppliers. The new requirement for a climate declaration for buildings aims at reducing the climate impact from construction and increasing reuse and recycling. Today, the modern wooden construction of multi-storey buildings in Sweden accounts for a market share of almost 15% and interest continues to grow. At present, residues from construction and demolition are often burned, although it could be pyrolyzed to achieve biochar that can be used as a carbon sink.

RISE offers research collaboration to develop life cycle analyses that shed light on the possibility of increased sustainability through up-cycling to biochar from the residues of construction with timber. We also welcome assignments from companies that want to develop construction towards higher sustainability.

The use of biochar as a method for carbon storage is pointed out as the technology that has the greatest realistic potential to contribute to negative emissions in Sweden in the middle of this century according to the Swedish Government. Different raw materials store different amounts of carbon based on composition. Heartwood has a high carbon content, which gives a high carbon content in biochar after pyrolysis. Residual streams from sewage treatment plants or animal manure give a lower carbon content after pyrolysis, but give rise to long-term carbon sinks. Chip boilers used for district heating could be converted into pyrolysis boilers and if the biochar is used as a soil improvement, the process gives rise to negative emissions. RISE provides expertise in LCA for pyrolysis of various raw materials and calculation of carbon storage potential.