Perennial Biomass Crops for Greenhouse Gas Removal

Miscanthus and short rotation coppice willow are regarded as the UK's most promising sustainable perennial biomass crops (PBCs). Both these crops have the capability of producing large amounts of harvestable biomass, very quickly, from low levels of input such as fertiliser and can be grown on land less suited to food production. They provide a renewable source of energy, which is broadly carbon neutral. For example, carbon is fixed by photosynthesis and when the crop is harvested and converted to energy, such as through combustion, that carbon is released again as carbon dioxide. However, when bioenergy is combined with carbon capture and storage (BECCS), the photosynthetically fixed carbon is not released back to the atmosphere, but is instead stored, for example, offshore. BECCS can therefore be used as a technology for greenhouse gas removal, to help the UK achieve its target to be "net zero" by 2050.

The planted area of PBCs is currently 7,000 ha of Miscanthus and 5,000 ha of willow. They are also relatively new crops, unfamiliar to many farmers. Our Perennial Biomass Crops for Greenhouse Gas Removal (PBC4GGR) project will undertake the research needed to enable Miscanthus and willow crops to be successfully scaled up, and rapidly enough, to respond to the climate change crisis. For example, we aim to develop the pathway from the current planting of 800 ha a year, to the 23,000 ha a year recommended by the Committee of Climate Change to meet the 2050 net zero target. Our project will demonstrate how the technical and social barriers to increased PBC production can be overcome, while maximising the amount of greenhouse gas removal and the environmental and social benefits which PBCs can deliver.

For PBCs to deliver their potential, we will be optimising the crop establishment agronomy needed to enable their rapid scale up. In addition, we will measure greenhouse gas fluxes on the land transitioned to PBCs and compare it to adjacent land remaining under conventional management. Combined high resolution CO2 fluxes, growth, meteorology and soil traits will be used to derive modelling parameters for UK wide greenhouse gas mapping. PBCs could be in the ground for up to 20, or even more, years so they can also increase soil carbon sequestered as well as providing a renewable feedstock for BECCS. Diversity in rooting depth and the presence of longer lived carbon compounds in root/rhizome will be screened to explore if opportunities for greater carbon sequestration could be bred into future varieties. Miscanthus and willow are both also capable of growing on more marginal land, so providing farmers with more options for diversification, at a time of change in the support schemes for farming, and also avoiding direct competition with primary food production. The large-scale changes in land use that greenhouse gas removal options will require need to be acceptable or even welcome to local communities, so we will investigate attitudes amongst the communities who may be affected. We will use a number of modelling approaches to understand the extent of scale up possible, the environmental impacts and the overall contribution of BECCS. Impacts of large scale PBCs on environment and rural economies will be forecast spatially and temporally and barriers to social acceptance will be assessed and addressed with innovative information on the opportunities and benefits for all. In conjunction with other Demonstrator projects and the Hub, we will seek to provide an integrated way forward that allows the UK to meet its net zero emissions.

The project is led by Aberystwyth University who have bred scalable Miscanthus varieties, and willow varieties have been bred by Rothamsted Research. Measurements of greenhouse gases are led by the UK Centre for Ecology & Hydrology, and modelling at Aberdeen will quantify greenhouse gas removal and economics. Gloucestershire will lead social science to understand perception barriers.