Utilization of Grassy Biomass Grown in Heavy-Metal Contaminated Soil as Feedstock for Bioenergy Production - An LCA Study

Abstract

Biomass is the only renewable source of carbon that, when utilized efficiently and optimally, can significantly help to reduce our reliance on fossil fuels. Certain types of perennial grasses, such as switchgrass, have great potential to be used as bio-renewable feedstock to produce bioenergy due to their relatively high yields of biomass per acreage of land. Furthermore, these grasses have the capability of extracting heavy metals from the contaminated soil, which in turn can improve the quality of the soil. A biorefinery process system consisting of two hydrolysis steps and a fast pyrolysis step to produce sugars and bio-oil using switchgrass grown in lead contaminated soil was studied. The study showed that the presence of lead in the grassy feedstock did not seem to affect the yields of sugars and bio-oil from the hydrolysis and the fast pyrolysis steps, respectively. An LCA study on growing switchgrass for soil phytoremediation using the switchgrass as feedstock for the biorefinery system was performed. Results from the study showed that the combination of using switchgrass as soil phytoremediation agent and feedstock for producing energy in a biorefinery decreases GHG emissions and lowers the use of energy produced from fossil fuels when compared with a combination of a refinery system and ex-situ excavation for soil remediation.