CO₂ footprint of the seeds of rubber (Hevea brasiliensis) as a biodiesel feedstock source

Crude rubber seed oil (CRSO) is a promising but currently underutilized biodiesel feedstock alternative, extracted by pressing the seeds of the rubber tree (Hevea brasiliensis). Rubber trees are cultivated across more than 11.4 million hectares worldwide, mainly in Southeast Asia. Despite their suitability as a biodiesel feedstock source, rubber seeds are currently treated as waste in the monocultural plantation system. To date, no assessments have been performed to examine the potential impact of rubber seed-based biodiesel production on GHG emissions. This study analyses the global warming potential of rubber seed methyl ester (RSME) production in Southeast Asia. The functional unit used is 1 MJ of biodiesel. A sensitivity analysis assesses the influence of key parameters (e.g., rubber seed yield) on the GHG mitigation potential. A scenario analysis evaluates the effect of using RSME by-products for energy generation. In comparison to fossil diesel, RSME has a carbon mitigation potential of 67 g CO₂.eq. MJ^-1, based on allocation by mass. On the condition of compliance with international sustainability standards that call for deforestation-free value chains, the generation of RSME biodiesel on rubber tree plantations in Southeast Asia would have a total mitigation potential of around 2.8 million tonnes of CO₂ eq. per year.