Airborne emissions from biomass based power generation systems

Generating electricity from biomass generates airborne pollution from the thermal conversion facility, but also from the upstream activities required to produce, process and provide the biomass. It is important that this is recognized in environmental evaluations of biomass power plants. Previous work had shown that off-site emissions could be significant for at least two particular bioenergy plants, but had not examined the extent to which this was likely to be generally applicable for a range of technologies and feedstocks; nor identified which steps were most likely to cause significant pollution. A number of bioenergy systems were modelled over whole life cycle to evaluate direct airborne emissions for short rotation coppice and miscanthus energy crops. This showed that CO and hydrocarbon emissions arise predominantly at the thermal conversion plant but up to 44% of NOx and 70% of particulate emissions could be released upstream. Transportation is a minor contributor; with harvesting and tractor transport potentially most significant.