Investigating the feasibility of a multi-conversion Miscanthus bioenergy crop

Plant biomass represents one of the most abundant renewable sources of carbon on our planet. About 70% of this biomass
consists of plant cell walls of which three quarters are polysaccharides. This biomass can be used as a renewable
feedstock for conversion into bioenergy (electricity and heat), biofuels (transport fuels) and biomaterials, thereby offsetting
greenhouse gas emissions associated with fossil fuel usage and providing alternative sources of energy and products.
Perennial grasses belonging to the Miscanthus genus can achieve high biomass yields with low requirements for
agricultural inputs, and have been identified as one of the primary energy crop candidates in the UK and other
geographies. As a home-grown perennial energy crop, Miscanthus will therefore be an important part of the UK's future
sustainable energy mix.
One of the key challenges for improving Miscanthus is to understand how different cell wall characteristics relate to
biomass quality targeted at different end uses, i.e. biochemical conversion to produce liquid biofuels and other
biomolecules and thermochemical conversion to produce electricity. Most biomass for bioenergy related research is
targeted to one of the potential conversion routes, either biochemical or thermochemical. However, an ideal scenario would
be to develop a multi-conversion Miscanthus crop possessing optimal properties for these two different conversion routes.
Another important aspect is the impact of biomass quality to milling and pellet production. Harnessing favourable traits for
all these features in a single crop would not only facilitate the marketing of the Miscanthus product, but also provide
flexibility to farmers and increase the economic resilience of rural communities. The current project will study the feasibility of developing such a multi-conversion crop using a multidisciplinary approach, utilizing the unique Miscanthus resources
that IBERS has assembled. More specifically, hybrids generated from a cross between two Miscanthus species (M.
sinensis and M. sacchariflorus) will be analysed in relation to their cell wall recalcitrance to sugar release, thermal
decomposition characteristics and selected sugar profiles (glycome analysis). Best performing hybrids will undergo further
detailed characterization in terms of cell wall biomass composition and architecture. The production of biomass pellets
offers significant advantages in terms of moisture content, energy density and transportation costs. However, the costs
associated with milling and pelletising are significant and the energy balance of the process and quality of the product is
biomass depended. The milling and pelletising properties of selected hybrids will be determined during a placement at
Drax, who owns the largest power station in the UK and is responsible for meeting 7-8% of the UK's electricity demand. It is
currently transforming itself into a predominantly biomass-fuelled generator, converting three of its six generating units to
run on sustainable biomass, including Miscanthus. Integration of the data relating to biochemical conversion,
thermochemical conversion, pellet production, and biomass composition and architecture for the selected hybrids will
reveal if the development of a single multi-conversion Miscanthus variety is an achievable goal or if we need to follow the
conventional route whereby different varieties will be matched to their end-use. Either way, detailed genotyping data
available for the hybrid population will facilitate identification of gene-trait associations related to biomass conversion
routes.
This collaborative research project between IBERS and Drax provides an excellent opportunity to deliver basic, strategic
and applied research that will provide essential information for developing better Miscanthus, ultimately contributing towards the establishment of a sustainable low-carbon bio-economy.