Empty fruit bunches (EFB) from the production of palm oil constitute a significant and increasingly problematic waste stream. Direct firing is hindered by a water content of 65 %. This paper investigates hydrothermal carbonisation (HTC) as one method of upgrading EFB waste to an exportable fuel. We first undertook bench experiments using EFB from Sumatra, Indonesia. The reactor was operated at 220 degrees C and the product was dewatered with a laboratory piston press to a water content of 32-37 %. The resulting dried HTC coal has an HHV of 28 MJ/kg and the process achieves an energetic yield of 73 %. If the process water is reused, the yield increases to 77 %. Between 10 and 80 % of the inorganic compounds remain dissolved in the process water. These results are used to calibrate a simulation model of an industrial scale HTC plant, using Aspen Plus software. Investment and operating costs are estimated for plant capacities of 0.04-0.1 megatonnes per year. 16 kJ of electricity and 67 kJ of boiler fuel are required for each MJ of EFB processed. The landed cost in Europe, with shipping, is 7.9-9.7 (sic)/GJ. Avoided greenhouse gas emissions can improve the economics: EFB are routinely dumped and release methane and the HTC coal can replace bituminous coal in power stations. The avoided net emissions are 190 and 100 kg CO2eq/GJ of HTC coal for avoided methane and avoided carbon dioxide, respectively.
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