A sticky and harmful by-product that has long hindered renewable energy production might soon be transformed into a valuable resource, according to a recent review published in Biochar.
When biomass materials like crop residues, wood, or other organic matter are heated to generate clean energy and biochar, they also produce a thick liquid called bio-tar. This tar can easily block pipelines, damage equipment, and pose environmental threats if released into the atmosphere. For years, researchers have been looking for ways to eliminate or neutralize it.
Now, a team led by scientists from the Chinese Academy of Agricultural Sciences suggests that, rather than viewing bio-tar as waste, it can be transformed into “bio-carbon” — a new material with applications in areas such as water purification and clean energy storage.
“Our review shows that converting bio-tar into bio-carbon not only solves a technical issue for the bioenergy sector but also opens up opportunities for creating advanced carbon materials with significant economic value,” explained senior author Dr. Zonglu Yao.
The review focuses on how chemical reactions within bio-tar, particularly those involving oxygen-rich compounds like carbonyls and furans, facilitate polymerization — a process where small molecules bond to form larger, more stable carbon structures. By optimizing temperature, reaction time, and additives, researchers can harness this process to create bio-carbon with specific properties.
The resulting material is different from regular biochar. Bio-carbon usually has higher carbon content, lower ash, and unique structural features that make it ideal for advanced applications. Early studies suggest that bio-carbon could be used as:
- Adsorbents to purify polluted water and air by capturing heavy metals and organic contaminants.
- Electrode materials for advanced supercapacitors, essential for renewable energy storage.
- Catalysts that accelerate industrial chemical reactions more sustainably than traditional fossil-based alternatives.
- Clean-burning fuels that emit fewer harmful nitrogen and sulfur oxides.
Importantly, recent economic and life-cycle assessments indicate that converting bio-tar into bio-carbon offers positive energy, financial, and environmental benefits. For instance, replacing coal with bio-carbon fuels could reduce carbon dioxide emissions by hundreds of millions of tons annually while also providing profits for biomass processing facilities.
However, challenges persist. The chemical complexity of bio-tar makes it difficult to monitor the polymerization process accurately, and large-scale production has yet to be achieved. The authors suggest that a combination of laboratory experiments, computer simulations, and machine learning could help optimize reaction pathways and design bio-carbon with targeted functions.
“Bio-tar polymerization is more than just waste management — it represents a new frontier for creating sustainable carbon materials,” noted first author Yuxuan Sun. “With further research, this approach could greatly enhance the efficiency of biomass energy systems while introducing new solutions for environmental protection and clean technology.”
The study offers a roadmap for scientists and industry partners to transform one of bioenergy’s biggest challenges into a powerful resource for the future.
Summary: A new review suggests that bio-tar, a problematic by-product of biomass energy production, can be converted into a valuable material called bio-carbon. This transformation could not only address technical challenges in the bioenergy sector but also create high-value products for water purification, energy storage, and clean fuels. While there are challenges in achieving large-scale production, ongoing research holds promise for leveraging bio-tar as a sustainable resource.
