THERMISOLN, LLC — Department of Energy SBIR Phase II: C54-22f

Description

Currently, climate change due to huge CO2 emissions is a well-recognized subject of widespread public concern. Global CO2 emissions are expected to double by 2030 if no specific countermeasures are taken. This substantial increase has been largely attributed to growing demands for the energy deriving from the combustion of fossil fuels such as coal, residue oil, and natural gases, which accounts for ~86% of greenhouse gas emissions. Carbon capture and storage (CCS) is thus of paramount importance, as it offers the opportunity to meet increasing demands for fossil fuel energy in the short to medium term, whilst reducing the associated greenhouse gas emissions. CO2 capture is the most expensive part of CCS, accounting for over 75% of the predicted overall CCS cost. As far as absorption solvents-based carbon capture is concerned, the huge energy penalty during rich solvent regeneration is a major concern for large-scale implementation of carbon capture technologies. Flue gas desulfurization (FGD)-produced gypsum is the 2nd most abundant type of coal ash. Many coal-fired power plants are plagued by continuously growing gypsum wastes that are simply stored in large open-air impoundments that occupy a significant amount of land and inevitably entail environmental problems. Gypsum dumped into landfills will be decomposed by sulfate-reducing bacteria, liberating up to a quarter its weight of very toxic H2S gas. Also, part of stockpiled gypsum wastes is gradually leached out by surface or underground water over time, thus leading to increased hardness of natural water resources. Efficient upcycling of gypsum wastes is thus of significance for our environmental protection and sustainable growth. The proposed effort addresses development of a switchable-hydrophilicity solvents (SHSs)-enabled absorption process for energy-efficient CO2 capture and fixation that overcomes all the issues mentioned above. The advantages of this technology mainly have five folds: (1) SHS-based CO2 capture approach is low-cost, energyefficient, and scalable, (2) low-T rich solvent regeneration enables us to greatly mitigate solvent evaporative loss, its thermal and oxidative degradation, equipment corrosion, and overall energy consumption, (3) delivery of a sustainable approach to effective waste valorization, (4) cogeneration of a value-added composite fertilizer in favor of faster plant growth, thus synergistically promoting more biological CO2 capture and fixation, and (5) deploying an affordable carbon capture technology that can achieve at least 90% CO2 capture efficiency from flue gas but without increasing the total cost of electricity (COE) by > 35%. Phase II will have 5 components, with major emphasis on the last one: (1) further development and improvement of a gas-liquid impinging scrubber, (2) design of a powerful decanter for efficient separation of oil phase from emulsions, (3) design of a CO2 desorber for rapid CO2 desorption at temperatures not hotter than 65 °C, (4) mitigation of solvent volatile loss, and (5) system integration and process intensification. Finally, an integrated prototype comprising all the key units will be built and tested in-house to demonstrate the technoeconomic advantages over other alternative carbon capture technologies on a bench scale. In the proposed CO2 capture process, besides the direct capture of CO2 gas, part of the CO2 present in flue gas is chemically immobilized by mineral carbonation to form limestone that could be used as an FGD sorbent in coal-fired power plants. Furthermore, the coproduction of a widely used composite fertilizer is favorable for faster plant growth, thereby promoting more biological CO2 capture and fixation. The combined process, CO2 capture paired with beneficial use of the process byproducts, could reach the DOE’s cost objective of ~$30/ton of CO2 captured. The recent dramatic increase in the cost of fertilizer will make the proposed process even more cost-effective. So far, technologies for large-scale carbon capture from a coal-fired power plant have been scarcely made available in the market due to quite limited energy efficiency involved. Following this R&D effort and the maturation of this technology, an energy-efficient post-combustion CO2 capture process could be commercially available in the market at an affordable price.