Innovative technological solutions for a biomass boiler with near-zero particulate emissions

The use of renewable bioresources as energy sources or as alternatives to fossil-based feedstock for the production of thermal or electric energy, or both simultaneously, has recently received much attention. Biomasses in general seem to be realistic alternative fuels leading to environmental, technical and economic benefits. However, in order to further increase the share of energy produced from biomass plants, it is necessary to improve the critical issues which to date have limited their spreading. In particular, environmental impact (particulate emissions) is identified as the most determining limit. The paper describes an innovative technological solution developed and tested at the University of Bologna to further increase biomass plant marketability and shows a preliminary design on how it can be integrated in a commercial biomass boiler for residential application. The innovation consists of a high efficiency and low cost filter for particulate emissions: the first prototype of bubble-column scrubber was tested in University of Bologna laboratory on a 25 kWth and reaches PM2.5 removal efficiency up to 95%. A second prototype is under development and testing and it is showing promising results in terms of both removal efficiency and cost reduction. The paper will show the last preliminary experimental results and evaluate how the new technology can be integrated in a residential size biomass boiler from a technological and economic point of view.