Simulation of Supercritical Water Gasification of Microalgae for Hydrogen and Methane-rich Gas Production

Abstract

The supercritical water gasification of Nannochloropsis sp, Spirulina sp. and Scenedesmus obliquus microalgae was examined using Aspen plus (V11) software. The influence of temperature (400 -700 °C ) and biomass concentration (10 -40 wt %) on the composition, yield and lower heating value (LHV) of the gaseous product was investigated. The results showed that low temperature and high biomass concentration favors the production of methane-rich gas while high temperature and low biomass concentration favors hydrogen-rich gas production. Higher CH 4 yield was observed at biomass concentration of 40 wt% which is an indication that the methanation reaction is accelerated at higher biomass concentration. The ranking order for the H 2 and CH 4 yield is Nannochloropsis sp> Scenedesmus obliquus> Spirulina sp. The highest LHV of 18.97 MJ/kg, 15.86 MJ/kg and 18.49 MJ/kg was obtained for Nannochloropsis sp., Spirulina sp. and Scenedesmus obliquus respectively at temperature of 400 °C and biomass concentration of 40 wt%.