Influence of Feedstock: Air Pollution and Climate-Related Emissions from a Diesel Generator Operating on Soybean, Canola, and Yellow Grease Biodiesel

Abstract

Global use of biodiesel is increasing rapidly. Combustion of biodiesel changes the emissions profile of diesel engines, altering their impact on both urban air pollution and climate. Here, we characterize exhaust emissions from conventional petroleum diesel and three neat biodiesels manufactured from soybean, canola, and yellow grease feedstocks. Exhaust was sampled from a fixed-speed 4.8 kW diesel generator at idle and full loads, and mass emission rates were determined for nitrogen oxides (NO, NO2, and NO x ), particulate matter (PM), and elemental, organic, and black carbon (EC, OC, and BC). Additionally, particle size distributions were characterized. Largely consistent with a growing body of data on emissions from biodiesel, biodiesel emissions were cleaner by most metrics than those for conventional diesel. Emissions from the two primary-oil fuels, synthesized from soy and canola feedstocks, were cleaner by most metrics than emissions from diesel, producing approximately 55, 65, and 60% less PM, EC, and OC at engine idle and 40, 20, and 15% less at engine load. In addition, while primary-oil NO x emissions were 5% higher than diesel emissions at engine idle, they were more than 30% lower at engine load. Yellow grease emissions of PM, EC, and OC were reduced in comparison to diesel at engine idle by 60, 30, and 20%. However, at engine load, most yellow grease emissions were increased in comparison to diesel, resulting in approximately 5, 60, and 70% more PM, EC, and OC. Organic vapor emissions from primary-oil biodiesels were also lower, and aromatic emissions were much lower compared to diesel. Yellow grease NO x emissions were increased in comparison to diesel by approximately 5% at engine idle and 10% at engine load. Notably, NO2 accounted for a smaller fraction of NO x for all three biodiesels compared to diesel, a difference that may be more important than the somewhat higher NO x emissions in determining the impact of biodiesel on urban ozone formation. Taken together, our results suggest that widespread implementation of primary-oil biodiesels could result in improvements in urban ozone and PM pollution. In addition, by reducing both the mass and the EC content of those particles, primary-oil biodiesels may reduce anthropogenic climate forcing.

Towards a sustainable approach for development of biodiesel from plant and microalgae

“…Lackey and Paulson [140] reported a better performance of exhaust emissions from biodiesel obtained from the edible feedstock (soybean, canola) as compared to the feedstock of waste origin (yellow grease). A higher particulate matter (PM) emission rate was also observed from yellow grease derived biodiesel as compared to mineral diesel.…”

Effects of fuel components and combustion particle physicochemical properties on toxicological responses of lung cells

“…Although the combustion of biofuels generally produces lower PM emissions than conventional petro-fuels, [14,15] some studies report that biofuels may modify emissions in ways that could adversely impact health as a result of increased particle-bound organic carbon content[16] and a higher respirable particle count,[16,17] due to a smaller mean particle diameter. [18,19] Furthermore, the higher oxygen content in biodiesel may lead to more reactive semi-volatile species and PM with greater oxidative potential.…”

Engineering increased triacylglycerol accumulation in Saccharomyces cerevisiae using a modified type 1 plant diacylglycerol acyltransferase

“…Biodiesel derived from plant TAG is nearly neutral with regard to production of carbon dioxide because the hydrocarbon chains of TAG (and biodiesel) are derived from the photosynthetic-driven capture of carbon dioxide (Durrett et al 2008;Lackey and Paulson 2011). There have been, however, serious concerns expressed about plant-derived biodiesel leading to increased food prices or environmental damage due to increased oilseed production (Durrett et al 2008).…”