Omnivore: a multi-feedstock biorefinery

Lead Research Organisation: University of York
Department Name: Biology

Abstract

There is a growing market for sustainable lignocellulosic bioethanol produced from crop residues and waste materials. Producing biofuels from these materials is challenging because none are typically available in appropriate quantities in a single location to support processing at the scale needed to cover capital investment. In addition, conventional processing of lignocellulosics produces fermentable sugar concentrations that are too dilute for effective fuel production, and overcoming this through complex processing or evaporative concentration is expensive. The Omnivore system will overcome the supply challenge by developing a feedstock agnostic lignocellulose processing system. Omnivore will overcome the sugar concentration challenge, by operating a hybrid system using first generation sugars to supplement the concentration of lignocellulosic sugars. The verifiable % of lignocellulosic biofuel will attract a double trading obligation credit, which will improve profitability.
 
Description We have identified conditions in which all straw species can be pretreated and digested with enzymes to yield high sugar concentrations for fermentation with lower enegy and enzyme inputs. We have found that waste paper and municipal solid waste (MSW) fibre do not benefit from thermochemical pretreatment. We carried out experiments to produce sugar solutions from mixed residue processing and ferment these to produce bioethanol. We found that yields from mixed biomass processing and fermentation were comparable to those carried out using a single feedstock, but there is no benefit from mixing the MSW fibre and paper with crop residues as the former do not require the thermochemical pretreatment required by the latter. Technoeconomic abnalysis of scaled up hydrolyses and fermentations showed that the only cost-competitive route to advanced bioethanol production using our methodologies was from working with MSW fibre. This is because the higher RED credits and gate fees could offset the cost of bioethanol production.
Work in this project has acted as a spark to initiate further work aimed at commercialising lignocellulosic technology. The understanding we gained from working at larger scalew and using technoeconomic analysis opened our eyes to some of the major cost barriers in commercialing lignocellulosic technologies. this has moved ust to work on two areas with higher value end products; namely,citric acid in a Newton Bhabha Reducing Industrial waste project, and bacterial cellulose production for textiles in a Follow-on Funding project. The realisation of the economic and environmental impacts of waste water from outr processes has caused us to radically rething the chemistries that we use and move to using combinations that result in a crop fertiliser by-product of considerable value instead of waste water requiring expensive disposal and treatment.
While the outcomes of the work could be considered rather negative, the learning from the work has had added value. The technoeconomic analysis revealed trhat waste water disposal is one of the most costly aspects of our proposeed pathway to bioethanol production. This has caused us to re-think our approach to biomass pretreatment (in particular) and develop methods whereby the products from this step may generate value rather than cost.
In addition, we have used the front-end (biomass processing) components of the techno-economic analysis to investigate potentially more cost-effective end products and this has led to a new focus on renewable cellulose production, which appears far more likely to yield a profitable outcome. We have applied for further funding to pursue this possibility.
Exploitation Route This work could underpin the development of a mixed feedstock biorefinery in the UK
Sectors Agriculture, Food and Drink,Chemicals,Environment,Manufacturing, including Industrial Biotechology,Transport