Biogas plant management decision support – A temperature and time-dependent dynamic methane emission model for digestate storages

The aim was to develop a temperature and time-dependent model that can calculate the methane production in an anaerobic digester and its subsequent digestate storage tank under realistic and variable conditions. With a daily resolution, the model was applied to a Swedish dairy farm under two different climatic conditions. The most influential parameters were hydraulic retention time and the substrate specific first order reaction rates in the digester, which have a big influence on the residual biogas potential, and hence the potential methane production in the digestate storage. The management of the storage can have a large impact on the emissions from the storage due to its temperature dependence. The model can be used to support plant design and operation of anaerobic digesters and storages, but further research is needed to determine first-order reaction rates and the relationship between the ambient and digestate temperatures at different times of the year. [Display omitted] •A temperature and time-dependent digester and digestate storage CH4 production model.•Variable substrate mixtures and residence times with a daily resolution.•Support for biogas plant designers and operators to reduce climate impacts.•Finding the optimal biogas plant design for different substrate mixtures.•Optimisation of digestate storage management strategies.