Process modeling, synthesis and thermodynamic evaluation of hydrogen production from hydrothermal processing of lipid extracted algae integrated with a downstream reformer conceptual plant

Hydrothermal processing of organics, particularly the supercritical water gasification process, has showed potential in lab-scale records to valorize the chemical energy stored in biomass. The technology manipulates the varying thermo-physical properties around the critical point of water to convert and upgrade the organic content, as well as extract inorganics. This study provides a systematic evaluation to the process upscaling into energetically efficient commercial demonstration. Conceptual plant flowsheets for a lipid extracted algae feedstock were developed on Aspen plus® for 99.9% purity hydrogen fuel production. The advantageous reactor system configuration is integrated within a layout that includes subsequent power generation and gas purification. The process is coupled with a downstream steam reformer block to maximize the poly-generation of hydrogen fuel, power and thermal heat. To thermodynamically evaluate the plant designs, minimum process utility demands were computed with the pinch analysis method, and different energy recovery scenarios, as well as alternative design configurations for optimal heat recovery were assessed. Finally, a comparative assessment showed that integrating downstream steam reforming with hydrothermal processing lead to an increase in the overall energetic efficiency from 34.2 to 46.2%, in the fuel-equivalent efficiency from 44.1 to 55% and exergetic efficiency from 28.9 to 41.4%.