BBSRC Centre For Sustainable Bioenergy (BSBEC): Programme 4: Lignocellulosic Conversion To Bioethanol (LACE)

There are three main drivers for the development of bioenergy and biofuels in the UK: Energy Security, Climate Change and Rural Development. Demand for oil is rising both from developed and developing countries and renewable alternatives are critical to ensure UK energy-security. Biofuels are fuels that are produced from plant material and are therefore renewable and will contribute to UK energy security. Biofuels also have the potential to deliver significant reductions in emissions provided that all stages of the supply chain are properly assessed and optimised. Lignocellulosic (plant cell wall) material is a valuable source of energy that can be derived from biomass crops and agricultural residues such as straw and spent grains. In addition this material may be derived from waste produced by industries that utilise wood and its derivatives. Harnessing the potential of lignocellulosic materials for the production of biofuels requires the deconstruction of plant cell walls using biological, chemical and physical processes to produce a fermentable feedstock. Furthermore it is essential that the processes developed limit the formation of toxic by-products (known as inhibitors) that reduce the potential for efficient fermentation. The fermentation of the liberated feedstock requires the development of appropriate strains that can use the range of sugars that comprise the cell wall whilst tolerating the process and product derived stresses. It is now vital that the UK addresses the challenge of effectively using lignocellulosic feedstocks to generate biofuels. To address this need, we will identify methods of feedstock production from plant cell wall materials that maximise sugar release but limit inhibitor formation. Furthermore we will develop super-tolerant yeast strains that can optimally ferment a range of sugars to form the biofuel ethanol. To achieve these aims Nottingham will build UK capacity in bioenergy and biofuels expertise by recruiting and training new talent and collaborating with multiple universities, institutes and companies. We will harness Nottingham's world class expertise in Fermentation, Microbiology and Biochemical Engineering, in close collaboration with Food scientists, Agricultural scientists and Social scientists. The University of Nottingham, which has international level researchers in all of these areas, will work in close collaboration with the Universities of Bath, Cambridge, Dundee, York, Newcastle and Surrey and Universities and Institutes in Africa, Europe, New Zealand and the USA. We will also work closely with Industry. We will focus on the generation of bioethanol from the lignocellulosic biomass including excess straw, spent grains and waste generated from food production. The processes used for this conversion will be optimized to reduce greenhouse gas emissions and maximize energy output. Waste materials produced from the process will be harnessed by identification of potential co-products streams including the production of materials for the construction industry and to produce non-liquid fuels. We propose to: (1) increase the UK scientific expertise in lignocellulosic digestion and fermentation; (2) develop the scientific foundations of technologies by identifying robust yeast strains that can be improved to enable them to utilize lignocellulosic feedstocks (3) ensure that the processes developed maximise energy outputs and minimise greenhouse gas emissions; and (4) provide avenues for the implementation of these technologies in industry whilst actively communicating our research with the wider global community.

The conversion of plant materials to fuels such as ethanol, butanol and biodiesels is a multi-step process sometimes referred to as a biorefinery. The key steps in the biorefinery are collection of the crop (which may be specifically grown as an energy crop, or be agricultural waste material), pre-treatment to make the lignocellulose more accessible, conversion of the sugars to a fuel molecule, and extraction of the fuel. There are several key challenges which need to be addressed to achieve sustainable conversion of lignocellulosic materials to fuels including: the accessibility and extraction of sugars using enzyme toolkits that can be applied to multiple plant biomass streams; the generation of fermentation substrates that are 'fit for purpose' for fermentation with low inhibitors and appropriate viscosity but are sustainable; the development of strains that can utilise the sugars liberated and efficiently convert them to fuels (in this case ethanol); the optimisation of fermentation to achieve a sustainable conversion. We will use a multi-disciplinary approach to address each of these key challenges. It is now widely recognised that biomass resources can be converted to produce so-called 'biofuels', 'bioheat' and 'bioelectricity' that have potential environmental benefits and greenhouse gas (GHG) savings. However, they also have possible side-effects in terms of emissions due to indirect land-use changes, loss of biodiversity, and competition with food production. Sustainability assessments are consequently required in order to ensure that net benefits flow from the utilisation of bioenergy resources. We will therefore also evaluate the sustainability of various bioenergy routes we propose to develop by applying the 'Three Pillars' of sustainable development: balancing of economic and social development with environmental protection.