Use of green chemical technologies in an integrated biorefinery

A new concept is demonstrated for an integrated close to zero waste wheat straw biorefinery combining two novel green technologies, CO2 extraction and low temperature microwave pyrolysis, to produce a variety of products, including energy and CO2 which can be internally recycled to sustain the processes. CO2 adds value to the process by extracting secondary metabolites including fatty acids, wax esters and fatty alcohols. Low temperature microwave pyrolysis (<200 °C) is shown to use less energy and produce higher quality oils and chars than conventional pyrolysis. The oils can be fractionated to produce either transport fuels or platform chemicals such as levoglucosan and levoglucosenone. The chars are appropriate for co-firing. The quality of the chars was improved by washing to remove the majority of the potassium and chlorine present, lowering their fouling potential. The economic feasibility of a wheat straw biorefinery is enhanced by intergrating these technologies.