(695c) Miscanthus Sacchariflorus Bioenergy Production

Carbon negative energy technologies are essential for achieving the 2015 Paris climate agreement goal, which specifies that the average global temperature should not rise 1.5°C over pre-industrial levels. Bioenergy with carbon capture and storage (BECCS) is one technique proposed for producing electricity and sequestering the resulting CO₂. However, recent work suggests that the traditional BECCS model may not be feasible at scale and its environmental benefits are highly dependent on the process design implemented (Fajardy and Dowell, 2017). In this work, we conduct a techno-economic and life cycle environmental assessment of a novel process design that may improve the energy efficiency and life cycle impact of traditional BECCS. Our process incorporates offsite pyrolysis for biochar production, reverse Boudouard gasification for biochar processing, and solid oxide fuel cells (SOFCs) for simultaneous electricity generation and low-cost separation of carbon dioxide. We simulated the process in Aspen Plus V10 assuming Miscanthus sacchariflorus biomass as the feedstock for biochar production. Our results indicate that a 500-megawatt SOFC power plant would require 0.5 megatons per year of miscanthus biochar to operate, while sequestering 1.5 megatons CO₂ per year. Pinch analysis was used to optimize the heat and power use in our proposed design, which resulted in a high thermal efficiency of the electricity generation site.