(328b) Corn Stover to High Value Carbon for Energy Storage

Worldwide, corn stover is generated in significant amounts. Using the integrated hydrothermal processing approach, corn stover can be converted into high value-added products such as bio-oil, hydrochar, and aqueous coproducts containing carboxylic acids and phenolics. Hydrochar is known to be porous that can be further activated by chemical/thermal methods to achieve high surface area carbon. In this investigation, hydrochar is activated with potassium hydroxide solution and heated to different temperatures, and characterized for specific surface area, pore size, pore volume, elemental composition, and surface functional groups. Energy storage performance of the activated carbons is analyzed in an asymmetric supercapacitor (ASC) configuration. ASCs possess higher cycle life as compared to batteries and superior specific capacitance as compared to electric double-layer capacitors (EDLCs) due to their charge storage mechanism by Faradaic reaction between the electrode and electrolyte. The process of hydrochar derivatization and activation is scaled-up at 1 tpd scale using ASPEN Plus modeling. Mass and energy balances are studied. Technoeconomic feasibility is determined at different production scales while considering costs associated with raw material, equipment, utilities, wastewater treatment and revenue from the carbon. LCA is also performed to understand the GHG emission for specific system boundary. Hydrochar production, carbon for energy storage, performance evaluation of asymmetric supercapacitor, scale-up, mass and energy balances, ASPEN modeling and TEA/LCA will be presented.