Reducing the negative human-health impacts of bioenergy crop emissions through region-specific crop selection

An expected global increase in bioenergy-crop cultivation as an alternative to fossil fuels will have consequences on both global climate and local air quality through changes in biogenic emissions of volatile organic compounds (VOCs).While greenhouse gas emissionsmay be reduced through the substitution of next-generation bioenergy crops such as eucalyptus, giant reed, and switchgrass for fossil fuels, the choice of species has important ramifications for human health, potentially reducing the benefits of conversion due to increases in ozone (O3) andfine particulatematter (PM2.5) levels as a result of large changes in biogenic emissions. Using theCommunity Earth SystemModel we simulate the conversion ofmarginal and underutilized croplandsworldwide to bioenergy crops under varying future anthropogenic emissions scenarios. A conservative global replacement using highVOCemitting crop profiles leads tomodeled population-weightedO3 increases of 5–27 ppb in India, 1–9 ppb inChina, and 1–6 ppb in theUnited States, with peak PM2.5 increases of up to 2 μgm .We present ametric for the regional evaluation of candidate bioenergy crops, as well as results for the application of thismetric to four representative emissions profiles using four replacement scales (10–100%maximumestimated available land). Finally, we assess the total health and climate impacts of biogenic emissions, finding that the negative consequences of using high-emitting crops could exceed 50%of the positive benefits of reduced fossil fuel emissions in value.