In response to the trend in the aviation industry to mitigate its environmental impact through the use of biocomposite materials, two research centres - Spain-based Aimplas and TNO in the Netherlands - collaborated on a new study researching different methods of chemical recycling for these biocomposites. Biocomposites use natural fibres for reinforcement and resins from renewable sources. However, the relative unfamiliarity with these thermosets, their heterogeneous nature and the fact that they lack carbon fibres, which have a high market value, make it difficult to find an efficient end-of-life solution.
The study looked at 12 methods for six different biocomposites, searching for the best technology in terms of technical and economic feasibility. The two most promising technologies were solvolysis and pyrolysis both of which were tested in large-scale production at a pilot plant. The results of the study, called the Eliot Project, revealed that pyrolysis emits 17% more carbon dioxide and consumes twice as much heat as solvolysis.
Solvolysis uses solvents as a substitute for heat, but these solvents are recovered with great efficiency and reused in the process. The study has also shown that solvolysis works even better on large biocomposites.
For both pyrolysis and solvolysis, additional purification steps are required to be able to use the pyrolysis liquid and the distilled product, respectively. These estimates were made based on a processing plant with a capacity of 10 kilotonnes of biocomposites per year.
Other technologies analysed in the study included mechanical recycling, dissolution, enzymatic degradation, gasification and composting.
The Eliot Project received funding from the European Union’s Horizon 2020 research and innovation programme within the framework of the Clean Sky Joint Technology Initiative under grant agreement number 886416.