Our Work

To achieve zero carbon targets and build sustainability into energy production, society is increasingly moving to biorenewable feedstocks as a replacement for fossil fuels as part of the renewables mix. Currently woody biomass is the dominant feedstock for bioenergy production via combustion, leading to increased demand and costs as well as wider concerns about sustainability.

Lignocellulosic crops such as straw produce abundant supplies of dry waste plant matter (biomass) which can be used as renewable feedstocks for energy production. However, they contain a high proportion of non-carbon components, which, during the energy production process leaves residues in the form of ash that can clog and corrode reactors leading to a need to temporarily shut down, clean and reset plant operations.

The focus was on investigating the effect of leaching on the removal of problematic ash constituents. Leaching is a known pre-treatment for coal, involving the use of demineralised water to wash the material under specific conditions, in order to remove problematic materials such as potassium, chlorine, sodium and sulphur, amongst others.

The researchers found that leaching successfully optimised the quality of these sludges by removing between 60-80% of undesirable ash components. Sugar deficient sludges from barley straw, wheat straw and bagasse were found to have a high calorific value and usability than their equivalent raw waste streams. The research confirmed conventional water leaching as a relatively cheap and scalable technology that could be implemented by bioenergy producers.

A second project, facilitated by THYME Follow-on Funding was called Refuel 2, and allowed us to extend the research by investigating if pyrolysis would be an effective way of upgrading biorefinery sludges. Pyrolysis is an existing technology to thermally convert solid biomass waste in an oxygen-free environment into different liquid and gas molecules. the team explored what other uses could be taken from the sludges by trialing 'fast pyrolysis', which produced predominantly bio-oil. Analysis of the bio-oil showed that it varied across the different sludge samples that were used, and that there were over 125 different extractable chemicals such as flavourings, fragrances, fuel molecules and fine chemicals were present.