Experimental Investigation of Bioenergy Production from Small-Scale Gasification of Landfill-Diverted Wood Wastes

Small-scale biomass gasification systems integrated with internal combustion engines can be a solution to the dual challenges of reducing greenhouse gas emissions from electricity production and reducing waste sent to landfills; however, these systems are typically designed for high-value, virgin wood chip feedstocks. This investigation aims to improve the feasibility of this technology by exploring the use of landfill diverted wood wastes (construction and demolition waste, used pallets and oriented strand board) in place of costly wood chips for the production of bioenergy in a pilot scale gasifier combined with an internal combustion engine generator operating at 10 kWe. The effect of feedstock bulk properties on gasifier operational stability and process parameters, including magnitude and variability of temperature and pressure drop, are investigated. Low bulk density (  55°) increased system instability through the formation and collapse of bridges and channels in the gasifier. Tar and particulate matter in the producer gas are quantified, as well as removal efficiencies of the gas clean-up for different feedstocks. Tar concentration in the syngas was in the range of 1.2 to 5.2 g/m3 downstream of gas clean-up, and was found to increase with system instability parameters and feedstock moisture. Finally, over the range of feedstocks examined in this study, a novel empirical correlation was developed to describe tar production from the gasifier as a function of feedstock bulk properties. The relationship between feedstock bulk properties and tar production is a unique finding and can enable to development of reliable waste-to-energy gasification systems.