Brazilian integrated oilpalm-sugarcane biorefinery: An energetic, exergetic, economic, and environmental (4E) assessment

Abstract

Given the imminent energy transition towards more sustainable and renewable energy systems, bioenergy represents an indispensable short and medium-term alternative. However, a key factor for developing the global bioindustry is establishing and consolidating integrated multi-product systems capable of efficiently and sustainably converting some organic materials into biofuels, bioelectricity, and other affordable bioproducts. Under this horizon, this work aims to evaluate and compare, through the thermodynamics precepts (1st and 2nd law), fixed capital investment, and life cycle analysis, different integrated bioenergetic complexes in which lignocellulosic material from oil palm and sugarcane cultures are processed simultaneously. These systems were structured for the Brazilian scenario, a country with a prominent role in bioenergy conversion, given its recognized soil and climate potential, large territory, and expertise in the bioenergy field. Consequently, this work presents a study of three scenarios: the first (CI), conventional palm oil biodiesel and sugarcane ethanol system; the second (CII) oilpalm–sugarcane biorefinery annexed to a lignocellulosic biomethanol plant; and the third (CIII) which is an extension of the second, but in this one, the concepts of advanced gas turbine integrated biomass gasification (BIG-GTCC) cycles are inserted. In this sense, a systematic analysis methodology is developed and implemented, which allows characterizing and measuring the energy, exergy, and environmental aspects related to the lignocellulosic material energy conversion, providing indicators that enable and facilitate the evaluation and selection of technologies that contribute to global energy decarbonization. The results obtained from the thermodynamic evaluation expose the advantage of getting a more prominent energy portfolio from various raw materials, with CIII standing out before the other scenarios, with superior performance in Global plant efficiency (53.4 %), Surplus Electricity Index (86.6 kWh tonMP−1), and Global plant exergy efficiency (62.7 %), associated with BIG-GTCC integrating, verifying how attractive it is for agribusinesses. From an economic point of view, integration is not feasible; however, it could be significantly improved through fiscal incentives founded on fossil energy use reduction, enhanced conversion yielding, and improvements in conversion technologies. On the other hand, the LCA results showed the potential environmental benefits associated with the fossil diesel partial substitution by biodiesel (considering methanol derived from lignocellulosic material), both in sugarcane and palm culture, enabling the fossil energy consumption reduction by 79.6 % (sugarcane) and 69.2 % (palm) by the methyl route. Consequently, Fossil Energy Ratio (FER) increases to 9 energy units and Life Cycle Energy Efficiency (LCEE) up to 52.6 % are achieved in the oilpalm–sugarcane biorefinery.