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

Purpose: Palm oil systems generate substantial amounts of biomass residues which are, according to best agricultural practices, preferably returned back to plantation in order to maintain soil fertility. However, there are often variations in this practice. Differences in economic status and possible treatment options for biomass residues determine the preferences to perform life cycle assessment (LCA), leading to a divergence in results. Difficulties when comparing LCA results based on literature are not unusual. The objectives of this paper are to provide guidelines for methodological choices that enable a systematic comparison of diverse scenarios for the treatment and valuation of empty fruit bunches (EFBs) and to explore effects of the scenarios on the environmental performances of a palm oil system.Methods: Eleven scenarios were selected to address the possible EFB valuation and expanded boundaries with reference to the main palm oil system (EFBs applied as mulch, converted to compost or ethanol, treated in an incinerator, and sold as coproducts). The life cycle inventories were modeled based upon an Ecoinvent database. Solutions to multifunctional problems were suggested, including the application of system expansion, substitution, and partitioning, depending upon the nature of the scenarios.Results and discussion: Comparison among LCA results based on the same multifunctional units (crude palm oil + palm kernel oil + palm kernel cake) can be accomplished only in cases where additional coproducts were utilized internally. Based on the global warming impact, the mulch option was preferred. The effect of the avoided process of producing synthetic fertilizers and the assumption that all parts of mulch are available as soil nutrient dominantly determined the final result. These need further verification. This study also demonstrates that the status of EFB as waste or goods is influential on the final results if the EFB is employed externally but has no effect if it is utilized internally.Conclusions: The proposed guidelines provide methodological choices in terms of system boundary, functional unit, and solutions to multifunctional problems. The methods can be used to systematically compare LCA results of different treatment options and valuation of EFB. The preferred alternative for managing this biomass residue could improve environmental performances and orient toward best practices, such as those suggested by the Roundtable on Sustainable Palm Oil (RSPO). Further studies incorporating a site-specific case of palm oil systems would better illustrate the usefulness of the proposed guidelines

LCA METHODS TO COMPARE TREATMENT OPTIONS ON BIOMASS RESIDUES PRODUCED IN A PALM-OIL SYSTEM

International audiencePalm oil systems generate large amounts of biomass residues. According to best agri-cultural practices, they are supposed to be returned back to plantation to maintain soil fertility. However, there are variations in practice. Differences in economic status and treatment options on biomass residues cause variations on the preference to perform LCA, leading to divergence in results that complicate interpretation. Difficulties found in comparing LCA results based on literature are not unusual. The objective of the paper is to provide guidelines on methodological choices to systematically compare diverse scenarios on the treatment and valuation of EFB (Empty Fruit Bunches) and to explore their effects on the environmental performances of a palm oil system. Eleven scenarios were chosen to cover possible EFB valuation and expanded system boundaries with reference to the main palm oil system (application as mulch, conversion to compost or ethanol, treatment in an incinerator, and EFB as direct co-products). The life cycle inventories were modeled based on Ecoinvent database. The input EFB was considered either as wastes or goods, and the resulted products were used internally or externally. Solution to multi-functional problems was suggested, including the application of system expansion, substitution, and partitioning depending on the nature of the scenario. The contribution of the plantation phases on global warming impact was so dominant that the effect of different scenarios could be observed only when focusing on the oil mill stage. Comparison among LCA results based on the same multi-functional units (crude palm oil + palm kernel oil + palm kernel cake) can be done only in the cases where additional co-products (mulch, compost, or ethanol) were used internally. Based on global warming impact, the mulch option was the best choice as compared to the compost, ethanol, or incineration options. The effect of the avoided process of producing substituted fertilizers was dominant in this comparison result. This study also demonstrates that the status of EFB as wastes or goods is influential to the final results when the EFB is used externally, but has no effect when it is used internally.The proposed guidelines provide methodological choices in terms of system boundary, functional unit, and solution to multi-functional problems. The methods can be used to systematically compare LCA results of different treatment options and valuation of EFB. The best alternative in handling biomass residues could improve environmental performances of the palm oil system and orient towards best practices, such as those suggested by the Roundtable on Sustainable Palm Oil. Further studies using a specific case of palm oil systems would better illustrate the usefulness of the proposed guidelines. Although the approach was illustrated for a palm oil system, it is also readily applicable for handling biomass residues in other agro-based industrial systems

PEMANFAATAN SERBUK GERGAJI SEBAGAI SUBSTITUSI BAHAN BAKAR PADA PROSES PEMBAKARAN - KILN DI PABRIK SEMEN DENGAN PENDEKATAN LIFE CYCLE ASSESMENT (LCA)

Cement production was a process that requires huge thermal energy and produces high greenhouse gas emissions. Co-processing or utilising alternative materials and alternative fuels for the combustion process in kiln was a solution to meet energy needs and reduce greenhouse gas emissions in the cement industry. This study aimed to analyze input, output, environmental impacts of cement production and calculate CO2-eq reduction from the system used alternative fuels on co-processing. The method used to determine differences and calculate CO2-eq reduction due to co-processing was life cycle assessment (LCA) and system approach. Based on the results of the LCA, the case 1 that used 100% coal energy required 3.50 GJ/ton-cement, 126 kWh/ton-cement, 2.19 L-diesel-oil/ton of cement and emited 0.84 ton-CO2-eq/ton-cement. Case 2 that had been substituted alternative fuels (saw dust) required 3.03 GJ per ton of cement, 118 kWh per ton of cement, 1.44 L diesel oil per ton of cement and emited 0.92 ton-CO2-eq per ton of cement. The results of global warming impact of  case 2 was higher than case 1. The assumption of  climate neutral made reduction global warming impact of case 2 by 14.65% and decrease CO2 emissions annually in plant by 71,601 tons CO2/year.  This result show that utilization of saw dust as biomass of climate neutral can be applied as an input for overall company specific emissions calculation to meet government regulation

Carbon Footprint of Semi-Mechanical Sago Starch Production

Indonesia is the country with the greatest potential for sago in the world. This research is intended to determine the carbon footprint of sago starch produced from a semi-mechanical process. The calculation was carried out using the LCA approach with the system boundary of cradle to gate. The process steps were carried out in a combination of manual work and diesel-driven engines. The inventory data on material, energy input flows and emissions were obtained from 3 samples of typical medium-scale semi-mechanical sago mills. It was found that the carbon footprint of the sago produced from semi-mechanical processes was 37.9±0.6 kgCO2 eq per 1 ton of dried sago starch. Further analysis shows that 62% of the carbon footprint comes from the extraction stage and 38% from the transportation. It can be estimated that the amount of greenhouse gas emissions from the semi-mechanical sago starch production in Indonesia for 2018 reached around 2,617,639 kg CO2 eq

LCA of second generation bioethanol: A review and some issues to be resolved for good LCA practice

This paper aims at reviewing the life cycle assessment (LCA) literature on second generation bioethanol based on lignocellulosic biomass and at identifying issues to be resolved for good LCA practice. Reviews are carried out on respective LCA studies published over the last six years. We use the classification of lignocellulosic biomass to define system boundaries, so that the comparison among LCA results can be thoroughly assessed based on identified system components. A basis for attributing environmental burden for different biomass feedstocks is also suggested. Despite the non-homogeneous systems, we conclude that second generation bioethanol performs better than fossil fuel at least for the two most studied impact categories, net energy output and global warming. For the latter category, carbon sequestration at the biomass generation stage can even consistently offset the GHG emissions from all parts of the life cycle chains at high ethanol percentage (≥85%). The aspect of biogenic carbon and agrochemical input for energy crops and biomass residues, and the effect of removal of the latter from soil have not been treated consistently. In contrast, the exclusion of upstream chain of biomass waste feedstocks is observed in practice. The bioethanol conversion process is mostly based on simultaneous saccharification and co-fermentation, characterized by high yield and low energy input. In this regard, the LCA results tend to under estimate the real impacts of the current technology. The choice of allocation methods strongly influences the final results, particularly when economic value is used as a reference. Substitution of avoided burden seems to be the most popular allocation method in practice, followed by partition based on mass, energy, and economic values

Production of sorghum pellets for electricity generation in Indonesia:A life cycle assessment

The current study makes use of life cycle assessment to evaluate the potential greenhouse gas (GHG) savings in coal electricity generation by 5% co-firing with sorghum pellets. The research models the utilization of 100 thousand hectares of under-utilized marginal land in Flores (Indonesia) for biomass sorghum cultivation. Based on equivalent energy content, 1.12 tons of pellets can substitute one ton of coal. The calculated fossil energy ratio of the pellets was 5.8, indicating that the production of pellets for fuel is energetically feasible. Based on a biomass yield of 48 ton/ha·yr, 4.8 million tons of pellets can be produced annually. In comparison with a coal system, the combustion of only pellets to generate 8,300 GWh of electricity can reduce global warming impacts by 7.9 million tons of CO2-eq, which is equivalent to an 85% reduction in GHG emissions. However, these results changed when reduced biomass yield of 24 ton/ha·yr, biomass loss, field emissions, and incomplete combustion were considered in the model. A sensitivity analysis of the above factors showed that the potential GHG savings could decrease from the initially projected 85% to as low as 70%. Overall, the production of sorghum pellets in Flores and their utilization for electricity generation can significantly reduce the reliance on fossil fuels and contribute to climate change mitigation. Some limitations to these conclusions were also discussed herein. The results of this scenario study can assist the Indonesian government in exploring the potential utilization of marginal land for bioenergy development, both in Indonesia and beyond