Dynamic Exergo-Economic Optimization and Polygeneration Dispatch of Biomass Gasification Coupled with Reversible Solid Oxide Cells and Carbon Capture

Abstract

Stand-alone biomass-to-power generation systems exhibit modest electrical efficiencies between thirty and thirty-five percent and poor economic competitiveness when operated as baseload units. Reversible solid oxide cells, capable of alternating between fuel cell power generation and electrolysis cell green hydrogen production, offer a pathway to flexible polygeneration. However, integrating fluidized-bed biomass gasification with ceramic cell stacks and amine-based carbon capture creates complex chemical and thermal coupling challenges, where rapid load switching can cause thermal shock, catalyst coking, and exergy destruction. This manuscript presents a dynamic exergo-economic optimization framework for a carbon-negative fifty-megawatt-thermal biomass gasifier coupled with a twenty-megawatt reversible solid oxide cell stack and an amine carbon capture and storage unit. We formulate a nonlinear thermodynamic chemical equilibrium model, with an electrochemical potential consistent with water-gas-shift equilibrium across the co-fed hydrogen and carbon monoxide fuel stream, linked to a predictive dispatch algorithm that dynamically switches between electricity export during high grid prices and hydrogen production during surplus renewable power periods. Simulations indicate the polygeneration plant achieves a round-trip exergy efficiency of fifty-eight point four percent, reduces the levelized cost of hydrogen to three dollars and fifteen cents per kilogram, and achieves a net carbon-negative emission footprint of negative seven hundred eighty kilograms of carbon dioxide per megawatt-hour, demonstrating financial viability under international carbon removal credit regimes.