(390an) Sorption Enhanced Chemical Looping Gasification of Biomass for Hydrogen and Transportation Fuel Production

The industrial production of H₂ and transportation fuels relies heavily on technologies that use synthetic gas or oils from gasification or pyrolysis of coal as fuel. These have extensive CO₂ emissions and thermodynamic inefficiencies owing to the unsustainable nature of the feedstock used and the multiple units required for product gas cleaning and conditioning. Sorption enhanced chemical looping gasification (SECLG) of biomass is a highly efficient technology designed to produce green H₂ and transportation fuels at competitive economic costs with the coal-fueled gasification and minimal impacts to the environment. However, the technology is presently underdeveloped with minimal work to date having focused on comprehensive modeling, techno economic analysis, life cycle assessment and its potential application to produce transportation fuels. As such, this work presents a comprehensive Lagrange Gibbs energy minimization process model for SECLG and its performance assessment in commercial and environmental matrices within the present and future energy systems.

Realising the potential of this technology would allow for the optimization of gasification technologies, low cost H₂ production and low carbon transportation fuels synthesis at economic costs readily within thresholds of coal-fueled gasification technologies. This work will be carried out in three steps i.e., process modelling, techno economic analysis and, life cycle assessment.

Process modelling: A comprehensive Aspen Plus model is developed using high performance Fe₂O₃ and NiO oxygen carriers with CaO used as sorbent material. The influence of parameters, including the fuel reactor temperature, pressure, equivalence ratio, and solid recirculation, are examined. Transitory-state pathways of solid carriers e.g., oxygen carrier and sorbent, during various redox loops, are evaluated. Eventually, a comprehensive SECLG model to produce H₂ and transportation fuel is developed.

Technoeconomic analysis: Economic cost scenarios linked to a biomass to gas (BtoG) and biomass to liquid (BtoL) plants for the SECLG of biomass are evaluated. Here, an n^th plant assessment considers operational costs, capital expenditure (CapEx), profitability assessment and a Monte-carlo uncertainty study. Within these, intricate parameters linked to the cash flow assessment, net present value and payback period are also determined. Consequently, the capacity of the BtoG and BtoL plants to economically compete with coal fueled gasification in modern energy systems is evaluated.

Life cycle assessment: The life cycle assessment considers further infant gate to gate modelling of SECLG within systematic bounds described in the technoeconomic analysis. Here, the BtoG and BtoL plants are evaluated at LCA midpoint, endpoint and cumulative energy demand levels within egalitarian Recipe and cumulative energy demand (CML) frameworks. The results of the LCA are further assessed via an openLCA Monte carlo uncertainty study to account for deviations within reasonable thresholds of the BtoG and BtoL inventory data. Eventually, the effects of the plants on the ecosystem and environment are assessed.