||The ETI commissioned AEA to provide an up-to-date assessment of current development and demonstration activities in EfW technologies, including both Advanced Thermal Treatment (ATT) and Anaerobic Digestion (AD) technologies
This document is the review of Anaerobic Digestion technologies. It found this to be a mature and successful technology. The main conclusions are:
This document is Appendix B2 (of 3) of the Energy from Waste UK Benefits Case (Deliverable 2 of 2 in Work Package 4).
- Single stage AD technology is relatively inefficient with respect to semi-solid waste, but will continue to be applied, with some modification, as it provides greater flexibility when feedstocks are prone to change from season to season or even daily.
- Multi-phase AD provides greater energy yield, but is relatively more costly (tankage, quality of digestate, high level of control etc).
- Pre-hydrolysis involving the use of chemicals or enzymes may prove too costly (the digestate will require different handling) to reach financial viability, but it will be important to keep abreast of the development with second and third generation biofuels, which look more promising.
- Hydrolysis of the hemicellulose and cellulose fractions of ligno-cellulosic materials is still at the development stage, although there are plans for demonstrations in the EU and USA. It is not clear whether this should be a priority for the UK at present, since the same feedstock could potentially be used in more efficient thermal processes such as gasification and pyrolysis.