Technologies for measurement and mitigation of particulate emissions from domestic combustion of biomass: A review

Energy from biomass is becoming increasingly important as fossil fuel reserves diminish. The utilization of biomass is already prevalent in the domestic heating sector, but produces significant amounts of particulates that are detrimental to human health. Mitigation technologies are well-developed for large-scale applications, but that is not the case at domestic scale. This review evaluates the various technologies that are available for mitigation of emissions from domestic combustion. Various other technologies are presented too, including those from the vehicular emissions field. The most common methods are the use of additives and catalysts, but both techniques are of limited effectiveness. The most notable technology is probably small scale electrostatic precipitators (ESP) which are under development and have been shown to be effective in reducing emissions. The effectiveness of mitigation technologies needs to be evaluated accurately through reliable particulate sampling methods. Some sampling methods can produce misleadingly low particulate emissions, indicating that mitigation technologies are not required, when this is not the case. Therefore, this paper also reviews the advantages and limits of different particulate sampling methods. Currently, different methods are used and most emissions are reported in terms of mass concentrations, which may not include the contribution from ultrafine particles. In particular, dilution sampling significantly affects particle emissions by promoting nucleation and condensation of volatile organic compounds. The resulting effect is an increase in formation of ultrafine particulates that are smaller in size, which are better represented by particle number measurements. However, varying methods and degrees of dilution are reported in the literature. The reporting of the particulate emissions (either in number or mass concentrations) is also too varied in its units, making comparison of emissions difficult. Thus, particulate sampling (and dilution) methods need to be standardized, as has been the case in vehicular emissions. (C) 2015 Elsevier Ltd. All rights reserved.