Road transport - Assessing the climate benefits of second generation biodiesel

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Why carry out this study? 

As we tackle the climate challenge, the mobility sector has no choice but to reinvent itself. By means of new practices, by addressing demand itself and by adopting new technologies: the scale of the challenge calls for action on every front. Consequently, efforts to support the low-carbon mobility transition must inevitably focus on the energy transition of road vehicles, independently of the necessary efforts to promote modal shifts and alleviate demand.

One generally acknowledged criterion used to rank the available energy options is the carbon footprint – evaluated over the full life cycle – of different types of vehicles, including private cars, light commercial vehicles, buses and tractor units. In 2020, to inform debate and help stakeholders make the best possible decisions in full possession of the facts, Carbone 4 published a summary of its research on the subject^[1], in which only the alternatives likely to see large-scale development were covered. This new publication supplements the first edition with a look at some more “niche” solutions, which typically raise many questions. Additionally, in our previous study, it was not possible to comprehensively address the subject of “biofuels”, as the field is rife with special situations, making a nuanced approach essential. In view of these two observations, this study looks at the most common “second-generation” biodiesels: fatty acid methyl esters, specifically those obtained from used cooking oil and animal fats.

What are we talking about?

The use of diesel biofuels (known as “biodiesels”) as a substitute for petroleum-derived diesel is a potential route for decarbonizing the transport sector. In 2019 in France, such fuels represented 7.3% of the energy contained in diesel^[1]. They mainly consisted ofFAME (“Fatty Acid Methyl Esters”) — which accounted for 87.5% by volume of biodiesel in France in the same year^[2], and synthetic biodiesels. 

“First-generation” FAME are obtained from vegetable oils extracted from oilseed crops (rape, soybean, palm, etc.) — these are known as VOME. “Second-generation” FAME, available in smaller quantities, may be obtained from:

• Used Cooking Oil — known as UCOME,
• Animal Fats — known as AFME,
• Or vegetable oil production waste (palm oil, rapeseed oil, etc.), sewage sludge and food waste — these FAME are currently produced in very small quantities and are not covered in this document.

This publication focuses primarily on UCOME and AFME — so-called “second generation” FAME.