Design strategies for oxy-combustion power plant captured CO2 purification

This study presents a novel design and techno-economic analysis of processes for the purification of captured CO2 from the flue gas of an oxy-combustion power plant fueled by petroleum coke. Four candidate process designs were analyzed in terms of GHG emissions, thermal efficiency, pipeline CO2 purity, CO2 capture rate, levelized costs of electricity, and cost of CO2 avoided. The candidates were a classic process with flue-gas water removal via condensation, flue-gas water removal via condensation followed by flue-gas oxygen removal through cryogenic distillation, flue-gas water removal followed by catalytic conversion of oxygen in the flue gas to water via reaction with hydrogen, and oxy-combustion in a slightly oxygen-deprived environment with flue-gas water removal and no need for flue gas oxygen removal. The former two were studied in prior works and the latter two concepts are new to this work. The eco-technoeconomic analysis results indicated trade-offs between the four options in terms of cost, efficiency, lifecycle greenhouse gas emissions, costs of CO2 avoided, technical readiness, and captured CO2 quality. The slightly oxygen-deprived process has the lowest costs of CO2 avoided, but requires tolerance of a small amount of H2, CO, and light hydrocarbons in the captured CO2 which may or may not be feasible depending on the CO2 end use. If infeasible, the catalytic de-oxygenation process is the next best choice. Overall, this work is the first study to perform eco-technoeconomic analyses of different techniques for O2 removal from CO2 captured from an oxy-combustion power plant.

Technoeconomic Evaluation of Recent Process Improvements in Production of Sugar and High-Value Lignin Co-Products via Two-Stage Cu-Catalyzed Alkaline-Oxidative Pretreatment

Background A lignocellulose-to-biofuel biorefinery process that enables multiple product streams is recognized as a promising strategy to improve the economics of this biorefinery and to accelerate technology commercialization. We recently identified an innovative pretreatment technology that enables of the production of sugars at high yields while simultaneously generating a high-quality lignin stream that has been demonstrated as both a promising renewable polyol replacement for polyurethane applications and is highly susceptible to depolymerization into monomers. This technology comprises a two-stage pretreatment approach that includes an alkaline pre-extraction followed by a metal-catalyzed alkaline-oxidative pretreatment. Our recent work demonstrated that H2O2 and O2 act synergistically as co-oxidants during the alkaline-oxidative pretreatment and could significantly reduce the pretreatment chemical input while maintaining high sugar yields, high lignin yields, and improvements in lignin usage. Results This study considers the economic impact of these advances and provides strategies that could lead to additional economic improvements for future commercialization. The results of the technoeconomic analysis (TEA) demonstrated that adding O2 as a co-oxidant at 50 psig for the alkaline-oxidative pretreatment and reducing the raw material input reduced the minimum fuel selling price from $1.08/L to $0.85/L, assuming recoverable lignin is used as a polyol replacement. If additional lignin can be recovered and sold as more valuable monomers, the minimum fuel selling price (MFSP) can be further reduced to $0.73/L. Conclusions The present work demonstrated that high sugar and lignin yields combined with low raw material inputs and increasing the value of lignin could greatly increase the economic viability of a poplar-based biorefinery. Continued research on integrating sugar production with lignin valorization is thus warranted to confirm this economic potential as the technology matures.

Selective cobalt and nickel electrodeposition for lithium-ion battery recycling through integrated electrolyte and interface control

Molecularly-selective metal separations are key to sustainable recycling of Li-ion battery electrodes. However, metals with close reduction potentials present a fundamental challenge for selective electrodeposition, especially for critical elements such as cobalt and nickel. Here, we demonstrate the synergistic combination of electrolyte control and interfacial design to achieve molecular selectivity for cobalt and nickel during potential-dependent electrodeposition. Concentrated chloride allows for the speciation control via distinct formation of anionic cobalt chloride complex (CoCl42-), while maintaining nickel in the cationic form ([Ni(H2O)5Cl]+). Furthermore, functionalizing electrodes with a positively charged polyelectrolyte (i.e., poly(diallyldimethylammonium) chloride) changes the mobility of CoCl42- by electrostatic stabilization, which tunes cobalt selectivity depending on the polyelectrolyte loading. This strategy is applied for the multicomponent metal recovery from commercially-sourced lithium nickel manganese cobalt oxide electrodes. We report a final purity of 96.4 ± 3.1% and 94.1 ± 2.3% for cobalt and nickel, respectively. Based on a technoeconomic analysis, we identify the limiting costs arising from the background electrolyte, and provide a promising outlook of selective electrodeposition as an efficient separation approach for battery recycling.

Utilization of Rooftop Solar Units to Generate Electricity and Hydrogen: A Technoeconomic Analysis

This study is aimed at scrutinizing the domestic solar energy potential for electricity and hydrogen production. Under the first scenario, it is sought to evaluate electricity generation for household purposes using RSUs (rooftop solar units). Then, under the second scenario, solar hydrogen production is analyzed for the purpose of meeting a hydrogen vehicle demand. For this, one of the aptest cities, Yazd, located in the center of Iran is investigated. Furthermore, a real-world electric load needed by an usual household in Yazd is deemed as the demand for electricity. To analyze the two scenarios, a system consisting of an 8.2 kW RSU for power generation, a battery for electricity storage, and a 1 kW electrolyzer for hydrogen yield is proposed. Also, to acquire a broader vision, predictions are made for the next 10, 20, 30, and 40 years. The results regarding the first scenario implied that COE (Cost of Electricity) would be, respectively, 0.067, 0.145, 0.136, and 0.127 $/kWh. In addition to supplying the electricity required by the house, 2,687 $/yr could be earned by selling the excess electricity generated, and 5,759 kg of CO2 would be avoided a year. The findings as to the second scenario showed that LCOH (levelized cost of hydrogen) would equate to 3.62, 6.53, 6.34, and 5.93 $/kg, respectively, for the aforementioned project lifetimes. Furthermore, 2,464 $/yr would be the revenue after selling the surplus electricity, and 7,820 kg of CO2 would be saved, annually.