The results of the preliminary techno-economic assessment for integrating a process utilizing low... more The results of the preliminary techno-economic assessment for integrating a process utilizing low-energy solvents for carbon dioxide (CO2) capture enabled by a combination of enzymes and ultrasonics with a subcritical pulverized coal (PC) power plant are presented. Four cases utilizing the enzyme-activated solvent are compared using different methodologies of regeneration against the DOE/NETL reference MEA case. The results are shown comparing the energy demand for post-combustion CO2 capture and the net higher heating value (HHV) efficiency of the power plant integrated with the post-combustion capture (PCC) plant. A levelized cost of electricity (LCOE) assessment was performed showing the costs of the options presented in the study. The key factors contributing to the reduction of LCOE were identified as enzyme make-up rate and the capability of the ultrasonic regeneration process. The net efficiency of the integrated PC power plant with CO2 capture changes from 24.9% with the ref...
ABSTRACT The objective of this project is to demonstrate a post-combustion carbon dioxide capture... more ABSTRACT The objective of this project is to demonstrate a post-combustion carbon dioxide capture process with the goal of improved efficiency, economics and sustainability compared with existing CO2 scrubber technologies. Tests are being conducted in an integrated bench-scale system that pairs the bio-renewable enzyme catalyst carbonic anhydrase with a low-enthalpy aqueous potassium carbonate solvent, and uses low temperature vacuum regeneration in a recirculating solvent-based process. Rationale for use of carbonic anhydrase is to promote inter-conversion between dissolved CO2 and bicarbonate ion, which is the rate-limiting step for absorption and desorption in solutions that rely on ionic complexation of CO2. Rationale for low temperature vacuum regeneration is that preliminary simulations have shown the use of very low pressure steam as thermal energy input during regeneration could lead to 43% lower parasitic power from a coal-fired power plant compared to MEA reference technology, including accounting for the compression penalty that comes with application of vacuum, which is required to increase the overall driving force for solvent regeneration at moderate temperatures (70-80°C bulk liquid temperature). Testing on the bench-scale unit is being carried out to compare experimental findings to simulated values, and update the simulation accordingly to enable predictions for a full-scale system. The bench-scale absorber (ID=7.6 cm; Raschig ring packed height = 2 m) is sized to treat 30 SLPM of simulated flue gas containing ~15% CO2, and is well-instrumented to monitor system performance. System shakedown tests demonstrated > 90% CO2 capture upon enzyme addition, corresponding to >75% improvement in % CO2 capture and 36% reduction in regeneration energy demand relative to the no enzyme case. The lowest energy demand (a further 30% reduction) achieved during unit shakedown testing occurred during an initial test of the simulated very low pressure steam (85°C) condition, albeit with 70% CO2 capture, versus < 25% capture in absence of enzyme. Parametric testing is currently in progress to determine conditions for conducting a 500 hour test with 90% CO2 capture, as well as provide data for kinetic-based ASPEN simulation. Enzyme replenishment is controlled by adding dissolved enzyme to the working solvent, meaning the enzyme travels along with the solvent as it recirculates through the absorber and stripper, and enzyme longevity under CO2 scrubbing conditions is being monitored. A description of the bench-scale unit, operational considerations, and results of the evaluations will be presented. This project is supported by funding from the U.S. Department of Energy’s National Energy Technology Laboratory.
The kinetics of the absorption of CO2 into two nonaqueous CO2 -binding organic liquid (CO2 BOL) s... more The kinetics of the absorption of CO2 into two nonaqueous CO2 -binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model.
The results of the preliminary techno-economic assessment for integrating a process utilizing low... more The results of the preliminary techno-economic assessment for integrating a process utilizing low-energy solvents for carbon dioxide (CO2) capture enabled by a combination of enzymes and ultrasonics with a subcritical pulverized coal (PC) power plant are presented. Four cases utilizing the enzyme-activated solvent are compared using different methodologies of regeneration against the DOE/NETL reference MEA case. The results are shown comparing the energy demand for post-combustion CO2 capture and the net higher heating value (HHV) efficiency of the power plant integrated with the post-combustion capture (PCC) plant. A levelized cost of electricity (LCOE) assessment was performed showing the costs of the options presented in the study. The key factors contributing to the reduction of LCOE were identified as enzyme make-up rate and the capability of the ultrasonic regeneration process. The net efficiency of the integrated PC power plant with CO2 capture changes from 24.9% with the ref...
ABSTRACT The objective of this project is to demonstrate a post-combustion carbon dioxide capture... more ABSTRACT The objective of this project is to demonstrate a post-combustion carbon dioxide capture process with the goal of improved efficiency, economics and sustainability compared with existing CO2 scrubber technologies. Tests are being conducted in an integrated bench-scale system that pairs the bio-renewable enzyme catalyst carbonic anhydrase with a low-enthalpy aqueous potassium carbonate solvent, and uses low temperature vacuum regeneration in a recirculating solvent-based process. Rationale for use of carbonic anhydrase is to promote inter-conversion between dissolved CO2 and bicarbonate ion, which is the rate-limiting step for absorption and desorption in solutions that rely on ionic complexation of CO2. Rationale for low temperature vacuum regeneration is that preliminary simulations have shown the use of very low pressure steam as thermal energy input during regeneration could lead to 43% lower parasitic power from a coal-fired power plant compared to MEA reference technology, including accounting for the compression penalty that comes with application of vacuum, which is required to increase the overall driving force for solvent regeneration at moderate temperatures (70-80°C bulk liquid temperature). Testing on the bench-scale unit is being carried out to compare experimental findings to simulated values, and update the simulation accordingly to enable predictions for a full-scale system. The bench-scale absorber (ID=7.6 cm; Raschig ring packed height = 2 m) is sized to treat 30 SLPM of simulated flue gas containing ~15% CO2, and is well-instrumented to monitor system performance. System shakedown tests demonstrated > 90% CO2 capture upon enzyme addition, corresponding to >75% improvement in % CO2 capture and 36% reduction in regeneration energy demand relative to the no enzyme case. The lowest energy demand (a further 30% reduction) achieved during unit shakedown testing occurred during an initial test of the simulated very low pressure steam (85°C) condition, albeit with 70% CO2 capture, versus < 25% capture in absence of enzyme. Parametric testing is currently in progress to determine conditions for conducting a 500 hour test with 90% CO2 capture, as well as provide data for kinetic-based ASPEN simulation. Enzyme replenishment is controlled by adding dissolved enzyme to the working solvent, meaning the enzyme travels along with the solvent as it recirculates through the absorber and stripper, and enzyme longevity under CO2 scrubbing conditions is being monitored. A description of the bench-scale unit, operational considerations, and results of the evaluations will be presented. This project is supported by funding from the U.S. Department of Energy’s National Energy Technology Laboratory.
The kinetics of the absorption of CO2 into two nonaqueous CO2 -binding organic liquid (CO2 BOL) s... more The kinetics of the absorption of CO2 into two nonaqueous CO2 -binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model.
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