Global scale CH4 emissions and electricity potential were calculated by applying CH4 emission and energy scaling factors to palm oil production statistics (Supplementary Tables 1–4 and Excel database). Error bars reflect the uncertainty in CH4 emissions at 95% confidence intervals based on potential variation in wastewater treatment conditions at mills throughout the tropics (Supplementary Table 4). We estimate that 5% of mills capture POME bioenergy pantropically (shaded portion).