Biomass is widely considered to be a renewable source of energy. It is often available in large quantities and at a low cost as a by-product of agriculture and forestry. Gasification is one of the most efficient and flexible methods for processing biomass. However, commercialisation of this technology is particularly hindered by the fact that biomass gasification tends to produce a fuel gas containing quantities of tar which can cause a number of operational issues.Our research at Imperial College has two main focuses: the first being the development of a simple protocol for assessing the suitability of different biomass feedstocks for gasification. The second involved investigating the impact of operating conditions such as temperature and presence of low-cost materials with potential catalytic activity on the pyrolysis product distribution, with the ultimate aim of eliminating residual tar compounds exiting the gasifier.The first part of our work utilised a fixed bed reactor to pyrolyse (the first stage of a gasification process) four types of biomass such that the products could be investigated. The products obtained i.e. char and tars were then characterised using a range of analytical techniques to determine their chemical and physical properties. The idea here being that the information gained could aid in the design of an optimal process for the gasification of a particular biomass or waste feedstock.The second strand of our research used a two-stage fixed-bed reactor where the first stage was employed as a tar generating zone and the 2nd stage as a tar cracking zone. The 2nd stage was operated empty to assess the effect of elevated temperatures on the tar yield, and loaded with a bed of either sand or sand and either calcined limestone or dolomite to investigate whether any additional cracking could be achieved by these materials.

Assessing the suitability of different biomass feedstocks for processing via gasification

248th National Meeting (2014)

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