Parallel production of biodiesel and bioethanol in palm‐oil‐based biorefineries: life cycle assessment on the energy and greenhouse gases emissions

Abstract

The main objective of this life cycle assessment (LCA) study is to determine the environmental consequences of the inclusion of second-generation biofuels (bioethanol from palm oil biomass) toward current palm oil biodiesel production through a 'seed-to-wheel' LCA analysis. Their energy and greenhouse gas (GHG) emission indicators are evaluated with consequential approach for system delimitation. Although all scenarios provide positive environmental impact, it is found that the inclusion of bioethanol production in the current palm oil processing will decrease the net energy ratio (NER) and net carbon emission ratio (NCER) values by 27.5% and 66.6%, respectively. Moreover, carbon emission savings (CES) value is also found to decrease by a total of 21.9%. This indicates that a higher amount of energy input and GHG emissions is actually required for the bioethanol processing than the amount of energy it will produce and the GHG from fossil fuels it will displace. The sensitivity analysis performed on the yields of bioethanol shows that the minimum conversion threshold should be larger than 60% in order to have a higher energy and GHG emission ratio than current palm oil biodiesel processing. Sensitivity analysis on direct land use change and waste-water treatment is also carried out which discourages the expansion of palm oil plantation to primary forest (including peatland) and emphasizes the need for a biogas harvesting system.

Comparative evaluation of lignocellulosic biorefinery scenarios under a life‐cycle assessment approach

“…On the other hand, environmental impacts per process unit, from the installation, construction, decommissioning, infrastructure, machinery, etc., have been considered negligible during the lifetime of a biorefinery facility. This has been a common practice in other biorefinery life‐cycle assessment studies The cogeneration unit of the plant supplies electricity to SS1, SS2, SS3, SS4 (except for on‐site enzyme production), SS6, SS7, SS8.…”

Sustainable design of biorefinery processes: existing practices and new methodology

“…For instance, Mu et al . assessed the environmental burdens (energy consumption and GHG emissions) of a palm‐oil‐based biorefinery. Third‐generation biorefineries, based on the use of algal biomass, are still not very developed.…”

“…Several studies highlight the potential environmental benefi ts of second generation biofuels compared to fi rst generation biofuels. For instance, Mu et al 58 assessed the environmental burdens (energy consumption and GHG emissions) of a palmoil-based biorefi nery. Th ird-generation biorefi neries, based on the use of algal biomass, are still not very developed.…”

Methodological issues in comparative life cycle assessment: treatment options for empty fruit bunches in a palm oil system

“…The latter process provides both a waste treatment function and a function intending to produce a certain product (Bellon-Maurel et al 2013). In this context, there has been increasing interest in utilizing EFB as a potential feedstock for bioenergy (Lim and Lee 2011;Wiloso et al 2012;Chiew and Shimada 2013) and other biorefinery products such as biochar, biooil, and syngas (Hansen et al 2012), but LCA studies addressing biomass residues within different valuation schemes are, thus far, lacking. The impact is directed entirely at the products and coproducts preceding the waste stream.…”