(476e) Carbon Negative Hydrogen Production From Biomass Based On Alkaline Hydrothermal Treatment

It is widely recognized that our current energy usage practices are untenable in the long-term. Emissions from fossil fuel energy sources, particularly CO2, have been shown to be responsible for anthropogenic global warming. The concentration of the current energy resources are often located in politically unstable areas, and thus, it has led to market volatility and engendered fears of energy security for countries reliant on those areas for energy. Thus, new energy sources must be developed, ones that are both sustainable and distributed.

The focus of this study is the development of an environmentally sustainable, compact energy conversion system that produces hydrogen from various biomass streams, particularly green algae. Biomass is an environmentally attractive energy source, which is renewable, distributed, and CO2 neutral. Currently, hydrogen is utilized in a number of applications: hydrogenation, ammonia and methanol production, and advanced propulsion systems. Hydrogen is also what powers the proton exchange membrane fuel cell (PEMFC). The PEMFC is the key component to a hydrogen economy, taking hydrogen and oxygen as reactants and producing water and electricity as products. Producing hydrogen for a PEMFC is complex, done in multiple stages in order to create a hydrogen gas pure enough for use in the PEMFC.

Compared to conventional gasification and pyrolysis, the proposed alkaline hydrothermal treatment is a less-studied method of biomass conversion but with great potential. The technology is scalable and has low parasitic energy consumption. By adding carbon dioxide capture, the system is not just carbon neutral, it is carbon negative. In this method, biomass is reacted with an alkali hydroxide to produce hydrogen and the respective alkali carbonate. Obviated is the need to remove CO through water-gas-shift or to capture CO2, for neither are byproducts of this reaction. With the addition of the proper catalyst, hydrogen yield approaches 100% of the stoichiometric quantity, while the operating temperature is far below that of gasification. In this study, the effects of temperature, pressure, biomass variety, type of alkali hydroxide, type of catalyst, flow rate of water vapor, and biomass pretreatment on the reaction kinetics and conversion are investigated.