Featuring of in-situ carbon capturing and functional performance study of hydrogen from aquaculture wastewater algae biomass via supercritical steam gasification route

Hydrogen energy is the trend and beneficial over fossil fuels, specifically in terms of zero carbon emission, eco-friendliness, and better energy efficiency. Algae are a potential source for hydrogen production, and the concentration of biomass leads to better hydrogen yield. This research aims to enhance hydrogen production from algae (using aquaculture wastewater) through a supercritical steam gasification process. The study will investigate different steam-to-biomass ratios (0.1, 0.3, 0.5, and 0.7) at a high gasification temperature of 1050 °C, under a gasification pressure of 23 MPa, and with a residence time of 30 min. During the gasification process, the potassium hydroxide (KOH) catalyst and sorbent injection are utilized to enhance the hydrogen yield. The titanium dioxide (TiO₂) nanoparticles are utilized for different percentages (0, 1, 3, and 5 %), and 5 % of TiO₂ favours optimum growth (0.95µ/day) microalgae, which is the feedstock for hydrogen production. The effect of steam to steam-to-biomass ratio on the functional behaviour of steam gasification for hydrogen production is evaluated. A higher steam-to-biomass ratio of 0.7 % is found to improve gasification efficiency (GE), hydrogen selectivity, and lower heating value (LHV), with KOH catalysis achieving a 54.7 % H₂ gas yield and increasing GE and LHV by 12.7 % and 23.4 %, respectively. Sorbent injection further increased GE to 54.3 %, hydrogen selectivity to 81.7 %, and LHV to 14.2 MJ/Nm³. The findings demonstrate the potential of TiO₂ nanoparticles and catalytic enhancements for improving biomass growth and hydrogen production efficiency.