Cascading Wood Use into Bioenergy with Carbon Capture and Storage Ensures Continuous and Enduring Temperature Reduction, Research by University of Galway and IEA Bioenergy Shows

Bioenergy with carbon capture and storage (BECCS) can provide so-called “negative emissions” (or carbon dioxide removal, CDR) which is considered a key component of pathways to net zero, yet potential interactions with forest carbon dynamics, cascading wood strategies, and progressive decarbonisation and CCS deployment are poorly represented in climate impact studies and life cycle assessments (LCA).

This study, published in Nature’s Portfolio Journal Communications Earth & Environment and conducted as a collaboration between the University of Galway and the IEA Bioenergy BECCUS strategic project, applied dynamic LCA to explore these factors for sawmill residue-derived BECCS value chains over long (more than 200 year) time-horizons. This perspective is important because recent studies suggesting that leaving forests unharvested is the best approach to deliver climate change mitigation do not account for future BECCS deployment (among other limitations).

Results of this study showed that the climate performance of bioenergy improved when combined with CCS to provide CDR. The BECCS system consistently delivers long-term global cooling, even in a fully decarbonised economy where substitution benefits diminish, provided that the wood sourcing does not result in forest carbon losses that outweigh the CDR contribution.

Cascading wood use delivers greater near-term cooling via product substitutions compared to direct diversion to bioenergy, and can store the biogenic carbon outside of the atmosphere long enough so that it can be transferred to permanent geological storage via end-of-life combustion in a BECCS facility (more likely to be widely deployed in 20-30 years’ time). At the same time, sustainably managed forests regrow to replace harvested trees, continuing to draw CO2 from the atmosphere, creating an enduring carbon removal pathway with a long-term cooling effect.

While providing less robust storage, unharvested forests can deliver stronger near-term cooling than wood harvesting for direct diversion to bioenergy, even with full BECCS deployment. However, carbon uptake in unharvested forests diminishes as such forests mature, and sequestered carbon may be vulnerable to disturbances such as drought, storms, wildfire, pests and disease. Crossover points in climate change mitigation achieved by unharvested forests versus BECCS value chains highlight the critical role of cascading wood use coupled with BECCS to ensure continuous and enduring cooling effects over coming decades.

In conclusion, transferring biogenic carbon from forests to geological stores, via multiple wood uses, is likely to enhance the longevity and resilience of CDR in a rapidly warming world.

Research & policy implications

• Stronger cross-sectoral coordination of bio-industrial policy is needed to incentivise cascading uses of wood (across multiple sectors and value chain actors) within the bioeconomy
• Legal and carbon accounting frameworks may need to be updated to accommodate international trade in biogenic carbon (storage) across value chains
• BECCS can make an important contribution to long-term decarbonisation alongside a material bioeconomy, but requires substantial near-term investment and policy support
• The climate effects of cascading value chains culminating in BECCS should be better represented in land use scenario modelling & policies, to provide a more complete picture on how the land sector can contribute to net zero goals

More information

Read the press release of the University of Galway.

The link to the research article and more information on the strategic programme on BECCUS can be found via this page at the IEA Bioenergy website.