Minimising the regeneration heat duty of post-combustion CO2 capture by wet chemical absorption: The misguided focus on low heat of absorption solvents

Oexmann, Jochen; Kather, Alfons

doi:10.1016/j.ijggc.2009.09.010

Cited by 290 publications

(211 citation statements)

References 6 publications

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“…The thermal energy required for the regeneration of the solvent in this plant is 410 MW th or 2.83 GJ th /t CO 2 , which is significantly lower than the reported values for the conventional alkanolamines, i.e., 3.5-4 GJ th /t CO 2 depending on the configuration of the capture plant, 85,86 i.e., a 20-30% lower.…”

Section: Cost Evaluationmentioning

confidence: 57%

“…This claim is true when the regeneration enthalpy is the only contribution considered, since the heat of regeneration of ionic liquids is considerably lower (∼2.8 GJ th /t CO 2 ) than that of conventional amines (3.5-4 GJ th / t CO 2 ). 85,86 However, a more detailed study on the total energy requirements shows that, in fact, the electricity, particularly that associated principally to the flue gas compression, imposes a high energy penalty which reduces the efficiency of the power plant from 40% (un-abated) to 28% (abated). Whilst reducing the absorption pressure would reduce the electricity demand of the capture plant, this work indicates that doing so would result in a significant increase in CAPEX.…”

Section: Resultsmentioning

confidence: 99%

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Challenges and opportunities for the utilisation of ionic liquids as solvents for CO₂capture

Mota-Martinez

Brandl

Hallett

et al. 2018

Mol. Syst. Des. Eng.

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Ionic liquids (ILs) have the potential to outperform traditional solvents for CO2 capture, with a great many ILs having been studied to date. In this contribution we present a new approach for their evaluation, and identify which physical properties most infl uence their technical and economic performance. This work highlights a range of potential challenges that ionic liquids will face before they can be applied at process scale, and identifi es some key research opportunities. Ionic liquids have been extensively investigated as promising materials for several gas separation processes, including CO 2 capture. They have the potential to outperform traditional solvents, in terms of their capacity, selectivity, regenerability and stability. In fact, hundreds of ionic liquids have been investigated as potential sorbents for CO 2 capture. However, most studies focus on enhancing equilibrium capacity, and neglect to consider other properties, such as transport properties, and hence ignore the effect that the overall set of properties have on process performance, and therefore on cost. In this study, we propose a new methodology for their evaluation using a range of monetised and non-monetised process performance indices.Our results demonstrate that whilst most research effort is focused on improving CO 2 solubility, viscosity, a transport property, and heat capacity, a thermochemical property, might preclude the use of ionic liquids, even those which are highly CO 2 -philic, and therefore increased effort on addressing the challenges associated with heat capacity and viscosity is an urgent necessity. This work highlights a range of potential challenges that ionic liquids will face before they can be applied at process scale, and identifies some key research opportunities.

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Section: Cost Evaluationmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO₂capture

Mota-Martinez

Brandl

Hallett

et al. 2018

Mol. Syst. Des. Eng.

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“…The ideal solvent capture process uses a solvent such as an aqueous amine with fast CO 2 absorption kinetics and a low heat of desorption to minimize the solvent regeneration energy. However, a high rate of CO 2 absorption kinetics for an amine solvent correlates with a higher temperature of desorption, whereas solvents with low heat of desorption tend to have much slower adsorption kinetics (3,4).…”

mentioning

confidence: 99%

Directed evolution of an ultrastable carbonic anhydrase for highly efficient carbon capture from flue gas

Alvizo

Nguyen²,

Savile

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

161

145

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Carbonic anhydrase (CA) is one of nature's fastest enzymes and can dramatically improve the economics of carbon capture under demanding environments such as coal-fired power plants. The use of CA to accelerate carbon capture is limited by the enzyme's sensitivity to the harsh process conditions. Using directed evolution, the properties of a β-class CA from Desulfovibrio vulgaris were dramatically enhanced. Iterative rounds of library design, library generation, and high-throughput screening identified highly stable CA variants that tolerate temperatures of up to 107°C in the presence of 4.2 M alkaline amine solvent at pH >10.0. This increase in thermostability and alkali tolerance translates to a 4,000,000-fold improvement over the natural enzyme. At pilot scale, the evolved catalyst enhanced the rate of CO 2 absorption 25-fold compared with the noncatalyzed reaction.carbonic anhydrase | directed evolution | carbon capture R eleasing over 9 billion metric tons of CO 2 worldwide each year, coal-fired power plants are the leading anthropogenic source of CO 2 emission. A potential solution to reduce the release of CO 2 into the atmosphere is the implementation of carbon capture and sequestration (CCS) technology on coal-and natural-gas-fired power plants. Currently, one of the most viable postcombustion CCS technology options uses an amine solvent to remove CO 2 from the flue gas (1). Unfortunately, the large amount of energy required to release the CO 2 and regenerate the solvent would significantly increase the cost of electricity generated (2). The ideal solvent capture process uses a solvent such as an aqueous amine with fast CO 2 absorption kinetics and a low heat of desorption to minimize the solvent regeneration energy. However, a high rate of CO 2 absorption kinetics for an amine solvent correlates with a higher temperature of desorption, whereas solvents with low heat of desorption tend to have much slower adsorption kinetics (3, 4).With reaction rates approaching the limits of diffusion, carbonic anhydrase (CA) is one of the fastest enzymes known. The active site of CAs can turnover CO 2 and water to bicarbonate and a proton up to a million times per second, and are used by almost every living organism to maintain pH balance and transport carbon dioxide. It has been shown that CAs can be used to accelerate the capture of CO 2 (5) by serving as a catalyst in alkaline capture solvents with slow absorption kinetics (6, 7). The potential improvements of CAs on CCS process economics stems from several considerations. The faster absorption and desorption kinetics allows for smaller processing equipment with reduced capital and operating costs (6). The improved kinetics also allows the use of lower temperature capture and solvent regeneration process conditions, and decreases energy losses in the capture process. Another benefit is the improved range of solvent candidates with attractive thermochemical stability (e.g., low vapor pressure, low formation of heat stable salts, etc.), but otherwise unacceptable unca...

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“…The mole ratio of carbonate to water in the unloaded referenced condition, R CW , is related to the mass fraction of K 2 CO 3 in the "as pure" condition (x 0 ), for example 0. weights of water and K 2 CO 3 , and , respectively, as observed in Equation 15. The calculation of the equilibrium constant for the data collected in the CLR can be observed in Table 7.…”

Section: Calculation Of Equilibrium Constant (K Co2 ) K 2 Co 3 Systemmentioning

confidence: 99%

Advanced Low Energy Enzyme Catalyzed Solvent for CO<sub>2</sub> Capture

Zaks¹,

Reardon²

2013

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A proof-of-concept biocatalyst enhanced solvent process was developed and demonstrated in an integrated bench-scale system using coal post combustion flue gas. The biocatalyst was deployed as a coating on M500X structured packing. Rate enhancement was evaluated using a non-volatile and nontoxic 20 wt% potassium carbonate solution. Greater than 500-fold volumetric scale-up from laboratory to bench scale was demonstrated in this project. Key technical achievements included: 10-fold mass transfer enhancement demonstrated in laboratory testing relative to blank potassium carbonate at 45°C; ~ 7-fold enhancement over blank in bench-scale field testing at National Carbon Capture Center; aerosol emissions were below detection limits (< 0.8 ppm); 90% capture was demonstrated at ~19.5 Nm 3 /hr (dry basis); and ~ 80% CO 2 capture was demonstrated at ~ 30 Nm 3 /hr (dry basis) for more than 2800-hrs on flue gas with minimal detectible decline in activity. The regeneration energy requirement was 3.5 GJ/t CO 2 for this solvent, which was below the target of <2.1 GJ/t CO 2 . Bench unit testing revealed kinetic limitations in the un-catalyzed stripper at around 85°C, but process modeling based on bench unit data showed that equivalent work of less than 300 kWh/t CO 2 including all CO 2 compression can be achieved at lower temperature stripping conditions. Cost analysis showed that 20% potassium carbonate in a basic solvent flow sheet with biocatalyst coated packing has economic performance comparable to the reference NETL Case-12, 30% MEA. A detailed techno-economic analysis indicated that addition of catalyst in the stripper could reduce the cost of capture by ~6% and cost of avoided CO 2 by ~10% below reference NETL Case-12. Based on these results, a directional plan was identified to reduce the cost of CO 2 capture in future work.

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Minimising the regeneration heat duty of post-combustion CO2 capture by wet chemical absorption: The misguided focus on low heat of absorption solvents

Cited by 290 publications

References 6 publications

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO₂capture

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO₂capture

Directed evolution of an ultrastable carbonic anhydrase for highly efficient carbon capture from flue gas

Advanced Low Energy Enzyme Catalyzed Solvent for CO<sub>2</sub> Capture

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Minimising the regeneration heat duty of post-combustion CO2 capture by wet chemical absorption: The misguided focus on low heat of absorption solvents

Cited by 290 publications

References 6 publications

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO2capture

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO2capture

Directed evolution of an ultrastable carbonic anhydrase for highly efficient carbon capture from flue gas

Advanced Low Energy Enzyme Catalyzed Solvent for CO<sub>2</sub> Capture

Contact Info

Product

Resources

About

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO₂capture

Challenges and opportunities for the utilisation of ionic liquids as solvents for CO₂capture