Sequential Temperature-phased Enhanced Anaerobic digestion using Microbes and Enzymes (STEAME)

Project Description

Ireland's energy vision by 2050 to reduce greenhouse gas emissions by between 80% and 95% compared to 1990 levels is ambitious and requires innovative technologies and radical transformations in the renewable energy sector. Renewable gas (biogas), which is commonly produced from anaerobic digestion (AD), has an important role to play in meeting these targets. However, few AD facilities are currently operational in Ireland, particularly when compared with other EU countries. One of the main reasons why AD has not taken off in Ireland is that the typical farmholds are relatively small and the capital and operational costs of running small-scale AD systems lead to poor financial returns. Furthermore, little work to date has been undertaken on optimising AD processes for the specifics of the main Irish feedstocks (cattle slurry and grass silage). The proposed project “Sequential Temperature-phased Enhanced Anaerobic Digestion using Microbes and Enzymes (STEAME)” is aimed at developing a cost-effective technology for the efficient conversion of farm-animal waste and surplus grass silage to biogas. Key innovations are developed in the areas of: pre-treatment; thermophilic semi-dry anaerobic digestion; and microbial and enzyme applications. These are expected to allow for increased biogas yields; avoid slurry storage; and produce stable class-A biosolids as a value-added product for agricultural land applications. These developments will improve the economics of farm-based small-scale AD systems in Ireland and allow for more facilities to be constructed, leading to environmental benefits through the utilisation of biogas rather than fossil fuels for energy generation. A prototype for the STEAME system will be developed and optimised for: maximum net energy production; reduced retention time; feed flexibility; and ease of operation with these optimisations leading to reduced capital and operational costs.