Methodological issues in comparative life cycle assessment: treatment options for empty fruit bunches in a palm oil system
- 840 Downloads
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.
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.
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.
KeywordsAllocation methods Bioethanol Biomass residues Compost Global warming Mulch Multifunctionality System boundary
Financial support from the Netherlands Fellowship Programs (NFP) for EIW is gratefully acknowledged. Appreciation is given to Indonesian Institute of Sciences (LIPI) for providing an opportunity for EIW to pursue a PhD study at Leiden University. The authors would like to thank the French National Research Agency (ANR) for the field trip support to Sumatera, Indonesia, within the frame of the SPOP project (http://spop.cirad.fr/) Agrobiosphere program. We also would like to thank Lauran van Oers of CML, Leiden University, for assisting with the CMLCA software and Bayuaji Kencana for useful information on palm oil biomass residues. The comments and suggestions from two anonymous reviewers are highly appreciated.
- Caliman JP, Suhardi, Pujianto (2013) Impact of by-products recycling on soil quality. In: Webb MJ, Nelson PN, Bessou C, Caliman JP (eds) Proceedings of workshop: sustainable management of soil in oil palm plantings, Medan, 7–8 November 2013.Google Scholar
- Doka G (2003) Life cycle inventories of waste treatment services. Ecoinvent report No. 13. Swiss Center for Life Cycle Inventories, St. GallenGoogle Scholar
- GAPKI (Indonesian Palm Oil Association) (2013) http://www.gapki.or.id/Page/CPOPrice?Index=7&selectedPage=0. Accessed 13 October 2013
- Haron K (2013) Sustainable nutrient management in oil palm ecosystem. In: Webb MJ, Nelson PN, Bessou C, Caliman JP (eds) Proceedings of workshop: sustainable management of soil in oil palm plantings, Medan, 7–8 November 2013Google Scholar
- ISO (2006) Environmental management—life cycle assessment—requirements and guidelines (ISO 14044). International Organization for Standardization, GenevaGoogle Scholar
- Jungbluth N, Chudacoff M, Dauriat A, Dinkel F, Doka G, Faist Emmenegger M, Gnansounou E, Kljun N, Schleiss K, Spielmann M, Stettler C, Sutter J (2007) Life cycle inventories of bioenergy. Ecoinvent report No. 17. Swiss Center for Life Cycle Inventories, DuebendorfGoogle Scholar
- Kusdiana D (2013) Existing and new bioenergy policies needed and implementation target. Paper presented at EBTKE Conference and Exhibition 2013, Ministry of Energy and Mineral Resources of The Republic of Indonesia, Jakarta, 21–22 August 2013Google Scholar
- Lee KT, Ofori-Boateng C (2013) Oil palm biomass as feedstock for biofuel production. In: Sustainability of biofuel production from oil palm biomass, Springer, Singapore, pp 77–106Google Scholar
- Nemecek T, Kägi T (2007) Life cycle inventories of agricultural production systems. Ecoinvent report No. 15. Swiss Center for Life Cycle Inventories, DuebendorfGoogle Scholar
- MPOB (Malaysian Palm Oil Board) (2012) Economics and industrial development division. www.mpob.gov.my. Accessed 3 February 2012
- Salétes S, Caliman JP, Raham D (2004) Study of mineral nutrient losses from oil palm empty fruit bunches during temporary storage. J Oil Palm Res 16:11–21Google Scholar
- Sheil D, Casson A, Meijaard E, van Noordwijk M, Gaskell J, Groves JS, Wertz K, Kanninen M (2009) The impacts and opportunities of oil palm in Southeast Asia. CIFOR, BogorGoogle Scholar