The role of wood in the chemical industry’s bio-based future

15/10/2024

The transition to a bio-based, carbon-neutral chemical industry is a significant goal in the broader mission to address climate change. As highlighted in a recent study by Wouter Arts and Ilié Storms from KU Leuven, wood could be a promising renewable carbon source to replace fossil fuels in producing chemicals in Europe. However, this transition is not straightforward. The study outlines the feasibility, challenges, and potential of using wood as a carbon feedstock, and emphasizes that while this shift won't happen overnight, it holds promise for creating a more sustainable chemical industry.

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Wood

The chemical industry relies heavily on carbon-based raw materials derived from coal, natural gas, and petroleum. These fossil fuels serve as feedstocks for high-value chemicals (HVCs) such as ethylene, propylene, and aromatic compounds like benzene. However, using fossil fuels contributes to significant CO2 emissions throughout the lifecycle of these chemicals. In Europe, the chemical industry processes around 92 million tons of carbon annually, emitting substantial amounts of greenhouse gases in the process.

The transition to renewable feedstocks like wood would require rethinking the industry’s carbon sources. Unlike energy sectors, which can switch to alternatives like green hydrogen or electricity, the chemical industry remains fundamentally carbon-based. This means finding renewable sources of carbon is critical.

Wood: renewable feedstock

Wood, as a form of biomass, offers an opportunity to provide renewable carbon. European forests cover 38% of the continent’s land area, supplying around 180 million tons of carbon annually in the form of primary woody biomass. However, much of this biomass is currently burned for bioenergy, raising sustainability concerns due to CO2 emissions and the depletion of forest resources.

The study emphasizes shifting wood's use from energy production to higher-value applications, particularly chemical manufacturing. This shift could align with the European Union's growing preference for “cascading use” policies, which prioritize using biomass for the highest economic and environmental benefits.

Processing wood

Wood is a complex material composed primarily of cellulose, hemicellulose, and lignin. These components contain carbon structures that can be transformed into various chemicals. However, converting wood into chemicals requires breaking down these structures through processes like gasification, fermentation, and chemical reactions to remove oxygen and produce hydrocarbons or other chemical building blocks. 

Concerning the technological pathways the authors write the following in their conclusion:

“(…) the exact amount of woody biomass available to produce chemicals will depend on the chosen technological pathway. Processing woody biomass into drop-in hydrocarbons, cracked into olefins and aromatics, requires large amounts of feedstock, or depends on the availability of green hydrogen. Oxygenate platform chemicals, resembling the elementary composition of the wood material, might be better product targets as they can be produced from the woody biomass with higher mass efficiency and less hydrogen.”

Balancing availability and demand

According to the study, the projected demand for carbon feedstock in the European chemical industry is around 65 million tons annually by 2050. This estimate considers a 50% recycling efficiency for chemical products, which limits the amount of fresh carbon needed. Interestingly, the estimated availability of woody biomass exceeds this demand, particularly when considering secondary woody biomass sources like sawmill residues and post-consumer wood. In theory, secondary biomass alone could cover up to 75% of the industry’s carbon needs.

However, not all woody biomass is equally accessible. The study points out that the availability of primary woody biomass might decrease in the future due to sustainability regulations and the impact of climate change on forest growth. Conversely, forest expansion and improved collection and processing of secondary biomass could increase availability.

Building a supply chain for wood-based chemicals

A crucial challenge for using wood as a chemical feedstock lies in establishing new supply chains. Currently, the wood and chemical industries are geographically distinct, with chemical production hubs located near maritime and industrial regions like Antwerp and Rotterdam, while wood processing occurs in forested areas. The study suggests that developing integrated wood refineries near forests could help bridge this gap.

These refineries could preprocess wood into intermediate products that can be transported to existing chemical sites, reducing transportation costs and emissions. Furthermore, integrating these refineries with existing chemical hubs would allow the industry to leverage its current infrastructure rather than building entirely new facilities.

Complex but feasible

While the idea of replacing fossil fuels with wood-based feedstocks might seem daunting, the study by Wouter Arts and Ilié Storms concludes that it is theoretically feasible. Achieving this transition will require a concerted effort across multiple industries, from forestry and bioenergy to chemicals and logistics. Importantly, the researchers stress that the focus should shift from burning wood for bioenergy to refining it into higher-value chemicals.

The study’s main message is that the availability of woody biomass, coupled with emerging technologies for chemical processing, presents a viable path for decarbonizing the European chemical industry. Although the practical implementation of this vision will take time and face various challenges, the findings offer hope for a sustainable future where wood replaces a significant portion of fossil-based feedstocks.

Key takeaways

  1. Wood as a renewable feedstock: Wood offers a viable source of renewable carbon to replace fossil fuels in the chemical industry.
  2. Technological pathways: The industry can explore hydrocarbon and oxygenate pathways to convert wood into chemicals.
  3. Supply chain integration: Building new wood refineries near forests and linking them to existing chemical hubs is essential for success.
  4. Focus on sustainability: Prioritizing chemicals over bioenergy could maximize the environmental and economic benefits of wood.
  5. Long-term transition: While immediate large-scale adoption isn’t feasible, the study’s findings highlight the potential of wood to transform the industry in the long run.

By redirecting wood’s usage toward sustainable chemical production, the European chemical industry has the opportunity to significantly reduce its reliance on fossil fuels. This shift, while complex, aligns with broader goals of achieving carbon neutrality and fostering a circular economy.

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