Pilot-scale demonstration and economics of the inversion process for sugar and ethanol production

A novel process for producing sugar and ethanol from high-yielding sugarcane called the Inversion Process has been developed previously. The process incorporates the use of an invertase-defective yeast to selectively ferment reducing sugars in sugarcane juice prior to crystallization to both produce ethanol and enhance the recovery of sugar from the process. To evaluate the technical and economic potential of the technology, the impacts of the Inversion Process on juice and syrup quality, crystal sugar production and recovery were evaluated using a three massecuite boiling scheme at pilot scale and techno-economic modelling was undertaken based on the results obtained. The Inversion Process decreased reducing sugar concentrations by >90%, which resulted in significant purity increases in clarified juice, syrup and A and B massecuites. These outcomes resulted in improved crystallization performance and reduced recycling of impurities. Lower C massecuite and C molasses purities were also achieved resulting in a significant impact on processability and recovery of sugar from C massecuite. Preliminary economic modelling showed the potential for very significant industry benefits with financial benefits accruing from increased sugar production and the production of ethanol from reducing sugars with the benefits of most significance for factories processing low-purity or high-yielding sugarcane. This paper reports on the demonstration of the Inversion Process in Australia and potential technical and financial impacts of the Inversion Process on the operation of sugar factories are discussed.