Life cycle analysis of ethanol obtained from lignocellulosic biomass: A case study of a native perennial grass from Argentina

The increasing concentrations of greenhouse gases (GHG) are the main cause of climate change. The scientific community agree that transition to renewable energies will play a key role as a mitigation strategy for this problem. In this work, an abundant biomass resource of central-eastern zone of Argentina is evaluated: rangelands of the Submeridional Lowlands dominated by Spartina argentinensis (espartillo). Bioethanol production from this species would not change the current land use; it has been assessed using a consequential Life Cycle Analysis (LCA) methodology. LCA was carried out with comparative objectives with the fuel to replace (gasoline). The functional unit was defined as “The production and use of 1 MJ of liquid fuel”. Two impact categories were considered: (i) Climate Change and (ii) Energy Use through global warming potential and energy return on investment (EROI), respectively. Gasoline's GHG emissions were 96.9 g of CO_2eq per MJ while the bioethanol obtained from espartillo was carbon negative in most scenarios. The EROI of gasoline had a value of 0.7 while bioethanol presented a range of 0.7 to 1.8. This LCA was realized with a consequential approach except for the by-products of fermentation at the biorefinery which were not considered to be used for any activity due to not having real data of such by-product; hence the obtained figures could be improved if these by-products were able to replace another product. The energy self-sufficiency of the plant and the avoided fires in rangelands are key factors to improve the environmental performance of bioethanol.