Exploring the potential uses of straw in the UK energy transition
To meet the UK’s net-zero carbon commitments, optimal use of biological resources must be considered. The UK produces over 10 million tons of straw each year as a co-product to cereal agriculture. This straw absorbs atmospheric carbon as it grows and can then be processed to sequester the embodied carbon or burned for renewable energy. Other competing uses for straw are animal feed, animal bedding and reincorporation into the soil.
Comprehensive studies on the full range of applications of straw are few, and they do not consider the trade-offs within the context of the UK, which has mature energy industries. This study evaluates the different domestic uses of straw with regard to the mitigation of greenhouse gas emissions and support of the agricultural industry.
Desktop research and a stakeholder interview were used quantify material flows, which are presented in Sankey diagrams. The carbon footprints of individual straw uses and their substitutes were then assessed.
Results indicate that direct combustion of straw for electricity is less effective at mitigating climate change than alternatives such as conversion to biofuel via anaerobic digestion. Thus further growth in this industry is not advised. Levels straw incorporation to the soil and use for animal feed should be maintained, while the use of straw for animal bedding should also be discouraged where sustainable alternatives are present.
Conversely, use of straw for construction is predicted to have a net emissions saving of 2.6 tonnes of CO2eq per tonne of straw. This is due to sequestration of the straw carbon and mitigation of brick use. If widely practiced, straw based construction could be by far the most impactful use of this resource. Consequently, this paper recommends that further research and policy development is conducted for the large-scaled deployment of straw buildings.