Energy-Efficient Carbon Capture Processes with Adsorbents Displaying Non-Traditional Isotherms

As atmospheric CO2 levels continue to rise, implementation of technologies for point source carbon emission (e.g. flue gas of coal-fired power plants) reductions are necessary for near-term carbon management strategies. Although current aqueous amine scrubbing technologies can achieve high levels of CO2 removal from flue gas, the thermal energy required reduces net plant power output by 20-35%, mainly as steam used for regeneration. The development of carbon capture processes with reduced energy usage and cost is of critical importance to rapid adoption of carbon capture processes. Solid adsorbents promise significant gains in energy efficiency owing to their reduced heat capacities and adsorption enthalpies, reducing energetic and economic costs of carbon capture when compared to traditional amine solutions. Specifically, a class of adsorbents developed at UC Berkeley that exhibit step-shaped CO2 isotherms has emerged as a promising candidate for CO2 removal from flue gas. The unique step-shaped isotherms offer two primary advantages: 1) large working capacities (10-16 wt%) can be realized at very low CO2 partial pressures, and 2) complete adsorbent regeneration can be accomplished with small changes in pressure and/or temperature, yielding significant energy savings. Over a decade of research on these materials has enabled rational “tuning” of the adsorption behavior of these materials; however, they have not yet been incorporated into a low-energy separation process. In this Phase I SBIR, Mosaic Materials will perform the preliminary engineering research required to develop a low-energy, modular separation process for carbon capture from flue gas utilizing step-shaped CO2 adsorbents. Synthesis of a modular separation process imparts flexibility to separation size, requirements and deployment schemes currently not available with solution-based amine scrubbing technologies. Identification of the optimal number of CO2 removal steps (i.e. separation modules), in addition to ideal CO2 adsorption step location, will yield a process capable of utilizing low-grade waste heat for a bulk of the regeneration required reducing energy requirements compared to current methods. Further, production of high purity (>95%) CO2 enables integration with emerging carbon utilization technologies. Completion of the preliminary engineering design will accelerate future development and validation phases of the high efficiency, low cost carbon capture process. Upon validation, rapid deployment of the modular capture process will dramatically reduce CO2 emissions with reduced derating of the associated power generation unit. Owing to the modular nature of the design proposed here, future adaptation to larger or smaller CO2 emission point-sources will be possible by simple addition or removal of already designed separation units. This project will expedite early commercialization and adoption of adsorbent-based flue gas carbon capture, benefitting both electricity generation and consumption markets.