Gasification of Bio-Waste and Biomass Products Through Exposure to High Density and Low Density Supercritical Water

Abstract

Biomass as a sustainable and renewable energy source is starting to gain momentum, especially as more economical energy extraction methods prevail. Supercritical water biomass gasification (SCWBG) is one of the more promising methods to extract energy from biomass in a gaseous form due to its lower temperature and simpler setup. In this work, two biomass samples (considered livestock feed) and two biomass waste samples are gasified in supercritical water (SCW). To compare the gasification of the real biomass samples (beat skin and straw) to previous works on model biomass compounds, two temperature states (hence different water densities) were used during gasification. An increase in temperature and decrease in water density was found to have similar effects on real biomass compared to that of model compounds. As temperature increases and water density decreases, combustible gas yields tend to increase due to changes in reaction pathways and reaction rates. In this work an analytical comparison is also made between the four different types of biomass in terms of which produce the most combustible gases and of which will generate the most energy. As a result of this analysis beet skins produce the most methane and corn silage yields the most hydrogen. It is the two bio-waste products, however, that generated the largest higher heating values (HHV).