Abstract
Anaerobic digestion (AD), one of the key technologies for achieving the climate-neutral target, is still facing various digestate management issues. The digestate's high organic matter and energy content make it a potential feedstock for further processing into value-added products, i.e., through thermochemical conversion technologies. However, its high moisture content poses additional challenges related to extensive energy requirement for feedstock drying. This paper investigates two technologies for efficient processing of digestate, i.e., 1) hydrothermal gasification (HTG) and 2) hydrothermal carbonization coupled with thermal gasification of hydrochar (HTC-TG). Both technologies can convert digestate into producer gas while avoiding the energy-extensive drying step. Aspen Plus software is used to compare the performance of the two processes. The process performance is comparatively assessed based on the producer gas generation and overall system efficiency (OSE).