Environmental and economic impacts of using brewers spent grains for animal feed and anaerobic digestion

Davison, Nicholas; Christodoulou, Christos; Humphries, David; Kliem, Kirsty; Stergiadis, Sokratis; Smith, Laurence

doi:10.1016/j.jclepro.2025.147365

Abstract

Over 130,000 tonnes of brewer's spent grains are generated annually in the UK. Most brewer's spent grains are utilised as a low-carbon animal feed, although anaerobic digestion provides economic benefits, through generating heat, energy, and biofertilizer. This study addresses a research gap by comparing both the economic and environmental impacts of using brewer's spent grains for animal feed versus anaerobic digestion. Specifically, it explores replacing brewer's spent grains-derived cattle feed with either high-carbon soya or UK-grown field beans, including dietary implications on methane generation and indirect land use change. Life Cycle Assessment and Life Cycle Costing were used to evaluate the environmental and economic impacts of utilising all brewer's spent grains generated in the UK for anaerobic digestion, as opposed to feeding cattle. Anaerobically digesting brewer's spent grains and using soya feed to replace brewer's spent grains as a cattle feed increased greenhouse gases by 39 Kt of CO2eq, while a field bean diet reduced emissions by 27 Kt of CO2eq. Additionally, the brewer's spent grain cattle diet required 6 and 8 thousand hectares less land than the field beans and soya diets respectively. However, anaerobic digestion of brewer's spent grains proved more profitable, offering an annual net economic benefit of 16 pound million. Thus, policy mechanisms such as an eventual ban could be introduced in order to phase out use of imported soya as an animal feed in the UK. Moreover, additional consultancy support, or interest free loans could be provided to facilitate breweries incorporating onsite anaerobic digestion.

Keywords

Brewer's spent grains; Life cycle assessment; Life cycle costing; Animal feed; Anaerobic digestion; Enteric methane; Land use change

Published in

Journal of Cleaner Production
2026, volume: 538, article number: 147365
Publisher: ELSEVIER SCI LTD

SLU Authors

Smith, Laurence
- Department of Biosystems and Technology, Swedish University of Agricultural Sciences
- University of Reading

UKÄ Subject classification

Environmental Sciences

Publication identifier

DOI: https://doi.org/10.1016/j.jclepro.2025.147365

Permanent link to this page (URI)

https://res.slu.se/id/publ/145739