Emergy-based sustainability analysis of bioenergy production from marginal and degraded lands of India

Abstract

Analysing the sustainability of cultivating biomass and biofuel plant species on marginal and degraded lands is essential for assessing the socio-economic and environmental perspectives. Various approaches have been suggested for the sustainability analyses, such as life cycle assessment, footprint analysis, multi-criteria decision analysis, and emergy analysis. Among these approaches, the emergy analysis is one of the most direct methods to assess the system's sustainability. The present article was aimed to perform the emergy analysis to quantify the ecological impacts, bioenergy potential, socio-economic efficiency, and the sustainability of the bioenergy production systems. The emergy-based sustainability analysis was conducted for the Soyabean-, Pongamia-, Jatropha-based biodiesel and Tectona-based biomass production systems from the Indian marginal and degraded lands. Results depicted that under a set of system boundaries for each plant species, total emergy output (U) of 1000 kg biodiesel (biomass in case of Tectona) was calculated to be 0.99E+16 for Soyabean-; 1.01E+16 for Pongamia-; 1.33E+16 for Jatropha- and 0.72E+16 sej for Tectona-based bioenergy production options. Emergy of fuels dominated the economic inflows (F) (32.53%) under the Soyabean-based option making it the second system to represent a greater environmental load ratio (ELR) of 17.98. Furthermore, the emergy of water resources was dominated under F in other studied bioenergy options, i.e., 38.08% of F in Pongamia-, 44.54% in Jatropha-, and 66.52% in Tectona-based systems. The emergy sustainability indices (ESI) of 0.06, 1.04, 0.34, and 0.02 were found for Soyabean-, Pongamia-, Jatropha-, Tectona-based bioenergy production systems, respectively. Sensitivity analysis further suggested that a decrease of 3.5% in F resulted in a 10.02% increase of ESI for the Pongamia-based option. Pongamia-based options depicted an ESI > 1, which could be considered to have a sustainable contribution to the economy for medium periods. The estimated ESIs were fundamentally low because the systems were dependent mainly on the F.