Vegetable oil-based biofuels, in particular, those produced from palm oil, are increasingly used as alternatives to fossil fuels, despite rising controversy over their sustainability. This has promoted to the continuous expansion of oil palm plantations across tropical regions, particularly in Indonesia.
But do palm oil-based biofuels actually reduce greenhouse gas emissions? A new study published on 27 February in Nature Communications suggests that only biodiesel from second rotation-cycle plantations or plantations established on degraded land reduce greenhouse gas emissions (1).
Lead author Dr Ana Meijide explained in a statement: “Mature oil palms capture high rates of CO2, but there are serious consequences for the environment from clearing forest. In fact, carbon emissions caused by cutting down forest to plant oil palms are only partially offset by the future carbon capture”.
The team of researchers from the University of Göttingen in Germany assessed the climate-friendly credentials of producing biodiesel from palm oil. The analysis was carried out using field-based measurements of greenhouse gas fluxes during different stages of oil palm cultivation in the Jambi province in Indonesia.
The results show that first-rotation palm-oil biodiesel creates 98 per cent more emissions than fossil fuels, mainly owing to the high emissions associated with forest conversion to oil palm. The researchers also looked at several alternative scenarios for generating higher greenhouse gas savings. They found that longer rotation cycles — 30 or 40 years versus 25 years — or earlier yielding varieties of oil palm can substantially reduce greenhouse gas emissions compared to fossil fuels.
According to Meijide, both of these alternative scenarios are ‘doable’. Moreover, she emphasises the importance of farming practices and government policies to prevent further losses of forest and promote longer rotation cycles.
Are palm oil-based biofuels truly a “greener” substitute for fossil fuels?
To meet the minimum greenhouse gas emission saving requirement for biofuels defined by the European Union in its Renewable Energy Directive, palm oil biodiesel must achieve at least a 60 per cent reduction in emissions compared to fossil fuels over its entire life-cycle.
From this point of view, the analysis does suggest that palm-oil biodiesel from second rotation plantations can indeed realise the greenhouse gas emission savings required by the EU directive. Moreover, the oil palm tree is more efficient in terms of land use than many other oil crops because it has the highest yield per area. Certainly, reducing greenhouse gas emissions will be crucial to mitigating further global warming and catastrophic climate change.
However, second-generation oil palm plantations support 20 per cent less diversity of invertebrates and 59 per cent fewer animals than the first generation palm oil plantations, according to another recent study published in Ecology and Evolution (2). This could have serious implications for soil biodiversity and agricultural sustainability, and should also be carefully considered.
(1) Meijide, A. et al. Measured greenhouse gas budgets challenge emission savings from palm-oil biodiesel. Nature Communications (2020). DOI: 10.1038/s41467-020-14852-6
(2) Ashton‐Butt, A. et al. Replanting of first‐cycle oil palm results in a second wave of biodiversity loss. Ecology and Evolution (2019). DOI: 10.1002/ece3.5218