Should industrial bagasse-fired boilers be phased out in China?

The industrial combustion of biomass, which has always been considered a source of clean and sustainable energy, might be phased out in China because it is believed to cause extremely high emissions of volatile organic compounds (VOCs), which are the key precursors in the formation of ozone and haze, although the emission factors have rarely been measured. In this study, the emissions of VOCs and several other air pollutants from typical industrial bagasse-fired boilers were measured for the first time. It was found that the emission factor (EF) of VOCs was 0.108 ± 0.034 g kg−1 (or 5.31 ± 1.68 g GJ−1 on an energy basis), which was roughly one order of magnitude lower than the officially recommended EF for industrial biomass combustion in China. In addition, the emissions of SO2, NOx and Hg from bagasse-fired boilers were even lower than those stipulated in the regulations for gas-fired boilers, with the exception of the particulate matter (PM), which was much lower than that produced during the open burning of biomass but higher than that from solid-fuel-fired boilers, likely as a result of the application of an ineffective dust removal device. It was demonstrated that the industrial combustion of biomass might produce much lower VOC emissions than expected and could help alleviate air pollution if biomass (at least bagasse) were used on a large scale instead of simply being burned in the field. In the future, dust removal devices with high efficiency should compulsorily be applied to industrial biomass boilers, and additional types of biomass fuel should be thoroughly evaluated to provide air-quality and energy policy makers with important insights.