Life cycle assessment of five vegetable oils
Introduction
The aim of this study is to generate life cycle assessment (LCA) results on a number of the major vegetable oils, and to generate evidence to inform consumers, industry and policy-makers of the potential environmental consequences of replacing any particular vegetable oil at the expense of another. The latter includes considerations of the market responses of taking out different vegetable oils from the market.
The study compares the environmental impacts of palm oil, soybean oil, rapeseed oil, sunflower oil and peanut oil. These five oils are among the six largest oils in the world in terms of global production volume, which is illustrated in Fig. 1. Palm kernel oil is produced in larger volumes than peanut oil, but since this oil is a joint co-product of palm oil, it is not considered separately. The considered vegetable oils are fully or partly substitutable for a large number of applications (Gunstone, 2011, Clay, 2004, In and Inder, 1997). The study only considered comparisons of the oils within the general market for unspecified vegetable oils, and hence the findings are not applicable for special applications where the oils are not substitutable.
Different vegetable oils systems are associated with different quantities of co-products, mainly oil meals which are used as animal feed. When studying market responses related to changes in demand for the different oils and when substituting different oils, it is a challenge to address the interactions among oils and with the feed markets. The studied product systems are identified using a systems perspective where likely market responses and substitution effects are considered. To achieve this, consequential modelling in life cycle inventory is used (Ekvall and Weidema, 2004, Weidema et al., 2009).
Previous research on comparative life cycle information on vegetable oils is relatively limited. Examples are Arvidssona et al. (2013) and Schmidt (2010). A larger number of studies exist within the field of biodiesel (e.g. Menichetti and Otto, 2009) which however are most often limited to focus only on GHG emissions compared to mineral diesel, and almost all of them use attributional modelling (Mentena et al., 2013) which is not relevant for the purpose of the current study.
Section snippets
Material and methods
The study generally follows the provisions set out in ISO 14040 and 14044 (ISO, 2006a, ISO, 2006b).
Results per tonne of oil
Table 4 shows the results of the impact assessment for each oil, on a per metric tonne basis. The results for soybean oil and palm oil are equal. This is because soybean oil is a dependent co-product, thus an extra demand for soybean oil does not affect the soybean oil production, but instead the production of palm oil. The GHG emissions are highest for peanut oil followed by and palm oil, sunflower oil and rapeseed oil in the mentioned order. The differences are mainly due to differences in
Discussion
The results per tonne of oil reveal that for GHG emissions and land use, the oils can be divided into a low impact (rapeseed and sunflower oil), medium (palm oil and soybean oil) and a higher impact group (peanut oil). In general the hotspots for GHG emissions for all of the oils are identified as the cultivation stage of oil crops including indirect land use changes. iLUC contributes with up to 34% of the total contribution to GHG emissions when excluding biogenic CO2 uptake stored in the oils
Conclusions
This study generates life cycle assessment (LCA) results on a number of the major vegetable oils, aiming at providing evidence to inform consumers and policy-makers of the potential environmental consequences of changing the demand and replacing the different oils. The modelling includes considerations of the market responses of changing the production of different vegetable oils, in particular the effects on the feed markets via the by-products of the oil, namely the protein meals, are
Acknowledgements
The Roundtable on Sustainable Palm Oil commissioned the original study which created the basis for studying the five different vegetable oils.
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