Indicative energy technology assessment of hydrogen processing from biogenic municipal waste

Abstract

An indicative appraisal has been undertaken of a combined Anaerobic Digestion and Steam Methane Reforming process to produce sustainable hydrogen from organic waste. The anaerobic digestion plant was based on the plant in Tilburg (The Netherlands), and was modelled from the kerbside organic waste collections through to methane production. Data on biogenic waste was obtained from a collection trial in a municipal area in the UK. This was scaled-up to match that of a Tilburg-like anaerobic digestion plant. The waste collection trials enabled the catchment area for an anaerobic digestion plant on a commercial scale to be estimated. A thermodynamic evaluation of the combined process included energy and exergy analysis in order to determine the efficiency of each process, as well as to identify the areas that lead to inefficiencies. The overall energy efficiency was 75% and the overall exergy efficiency was 60%. The main energy losses were associated with compressor inefficiencies. In contrast, the main exergy consumption was found to be due to the fermentation in the digestion tanks. Other hydrogen process efficiencies vary from 21% to 86%, with the higher efficiencies belonging to non-renewable processes. However, the sustainable hydrogen produced comes from entirely renewable sources (biogenic waste) and has the benefit of near-zero carbon emissions in contrast to fossil fuels. Finally, the case study included an indicative financial assessment of the collection to processing chain. A discounted payback period of less than 20 years was estimated with a modest annual charge for householders.