Greenhouse gas emissions and non-renewable energy use profiles of bio-based succinic acid from Arundo donax L. lignocellulosic feedstock

Abstract

The European Union recognizes the priority of new bio-based industrial pathways, such as bio-based succinic acid (bio-SA). This study has investigated, through a life cycle method, the cradle-to-factory gate greenhouse gas (GHG) emissions and non-renewable energy use (NREU) of bio-SA from lignocellulosic giant reed (GR) feedstock grown on marginal lands in Southern Italy (GR bio-SA). The aims were to: (1) evaluate the environmental performance of the GR bio-SA and (2) discuss the GR bio-SA profile with respect to its fossil counterparts and alternative bio-SA routes. For 1 kg of GR bio-SA, the gross GHG emissions amounted to 3.9 kg CO2 eq, while through the inclusion of the biogenic C potentially stored in SA molecule (1.47 kg CO2 eq) and soil organic matter (0.44 kg CO2 eq), the final net global warming potential would be nearly halved. Similarly to current starch-based SA supply chains, the GR bio-SA showed: (1) better gross GHG profile compared to the fossil adipic acid (GHG emissions reduced by 55%) and (2) comparable net GHG emissions in comparison with petrochemicals SA and maleic acid. The total NREU for 1 kg of GR bio-SA amounted to 26.6 MJ, with reduced energy consumption by about 55–79% relative to fossil counterparts, thanks to the on-site energetic valorization of lignin and holocellulose residues with relatively high heating values. The soy protein concentrate and the inorganic chemicals used in the co-fermentation showed up the prevailing contributions to the GHG and NREU profiles of the GR bio-SA, suggesting the need to optimize nitrogen and carbon sources of the growth medium.