Post-combustion Carbon Capture Plant Research Articles

Hybrid Advanced Control Strategy for Post-Combustion Carbon Capture Plant by Integrating PI and Model-Based Approaches

Even though the energy penalties and solvent regeneration costs associated with amine-based absorption/stripping systems are important challenges, this technology remains highly recommended for post-combustion decarbonization systems given its proven capture efficacy and technical maturity. This study introduces a novel centralized and decentralized hybrid control strategy for the post-combustion carbon capture plant, aimed at mitigating main disturbances and sustaining high system performance. The strategy is rooted in a comprehensive mathematical model encompassing absorption and desorption columns, heat exchangers and a buffer tank, ensuring smooth operation and energy efficiency. The buffer tank is equipped with three control loops to finely regulate absorber inlet solvent solution parameters, preventing disturbance recirculation from the desorber. Additionally, a model-based controller, utilizing the model predictive control (MPC) algorithm, maintains a carbon capture yield of 90% and stabilizes the reboiler liquid temperature at 394.5 K by manipulating the influent flue gas to the lean solvent flowrates ratio and the heat duty of the reboiler. The hybrid MPC approach reveals efficiency in simultaneously managing targeted variables and handling complex input–output interactions. It consistently maintains the controlled variables at desired setpoints despite CO2 flue gas flow disturbances, achieving reduced settling time and low overshoot results. The hybrid control strategy, benefitting from the constraint handling ability of MPC, succeeds in keeping the carbon capture yield above the preset minimum value of 86% at all times, while the energy performance index remains below the favorable value of 3.1 MJ/kgCO2.

Use of artificial intelligence in reducing energy costs of a post-combustion carbon capture plant

Absorption-based carbon capture (ACC) is the most mature technology for abating CO2 among different post-combustion carbon capture technologies. ACC is, however, energy-intensive and requires large heating and cooling utility consumption, resulting in high operational costs. Reliable and fast estimation of these utility consumptions would be valuable for technical and financial feasibility assessment of different ACC process designs. The objective of this study is to develop an artificial intelligence (AI) based approach that predicts these utility consumptions of different ACC process designs. For prediction of specific reboiler duty, which is the most important energy consumption of the plant and the main source of operational costs in the ACC process, the error of the AI models is between 0.4% and 3.6% for different scenarios of utilizing either limited or extensive training data. Moreover, the contribution of each process parameter to energy consumption was identified using explainable artificial intelligence. The findings of this study facilitate the energy-efficient design of ACC plants and provide a prioritized list of parameters to adjust for reducing the energy consumption of an ACC process.

Design and multi-objective optimization of a CO2 capture plant using deep eutectic solvents

The United Nation’s 2030 Agenda for Sustainable Development has called for taking of urgent action to combat climate change and its impacts, where CO2 capture processes have gained relevance for achieving emission objectives. Traditionally, monoethanolamine (MEA) is used in post-combustion capture (PCC) as a solvent because of its high absorption capacity. However, the use of amines is related to several environmental problems. In this work a novel post-combustion carbon capture plant is designed in Aspen Plus, under a sustainable design scheme considering environmental and economic indexes, using novel green liquids: deep eutectic solvent (DES) choline chloride/urea (1:2). Four case studies are considered for the most used fossil fuels in the power plant: coal, natural gas, associated gas, and biogas. This work represents a base case for multi-objective optimization of the PCC process coupled with a power plant for combustion. An optimization problem was defined considering the following objective functions: minimization of the environmental impact (EcoIndicator 99), minimization of the total solvent recovery energy (TSRE) and greenhouse gas emissions (GHGE); the economic objectives were set to minimize the total annual cost of the plant (TAC) and maximize return over investment (ROI). A metaheuristic optimization method, differential evolution with tabu list was chosen, and Pareto fronts for the objective functions were obtained for all case studies. It was found that the PCC process for coal-based power generation exhibits the best overall performance among all evaluated fuels. A comparison with a similarly optimized MEA-based carbon capture process shows that the use of DES leads to a 171.8% reduction in environmental impact when treating flue gas from a coal-based power process. To showcase the feasibility of the DES as a green solvent, an energy consumption of 6.62 MJ/kgCO2 is needed, compared with 6.40 MJ/kgCO2 for the MEA-based process.

Dynamic Modeling and Control of a Simulated Carbon Capture Process for Sustainable Power-to-X

The goal of this study is to develop a dynamic model for a Carbon Capture (CC) process that can be integrated with a water electrolysis facility. The possibility of operating the post-combustion CC plant dynamically is investigated. The final model successfully tracks the parallel hydrogen production, providing the stoichiometric required CO2 stream for the subsequent methanol reactor. A dynamic model is used to configure controllers and to test the unit performance and stream conditions for various set points. Through the transient operation, the required feed gas is provided while optimizing the solvent and energy requirements. It is found that the slowest acting stage is the reboiler with a time constant of 3.8 h. Other process variables stabilize much quicker, requiring only a few minutes to reach steady-state conditions. The hydrogen-tracking scenario shows that the carbon capture plant can successfully operate under varying conditions with a maximum CO2 output increase of 7% of the minimum flowrate in the representative 24 h simulation time. The output CO2 stream is maintained at the desired >98% purity, 25 °C temperature, and 1.85 bar pressure, which allows to successfully perform hydrogen tracking operations.

Co2 Capture and Work Environmental Sampling - Lessons Learned

With almost a decade of operational experience from an amine-based post combustion carbon capture plant in Norway, Technology Centre Mongstad has under multiple occasions and operating scenarios monitored the work environment exposure risk for such facilities. Primary focus has been on concentrations of Nitrosodimethylamine in the work environmental atmosphere. This paper presents some findings from work environmental gas sapling collected between 2012 and 2020, where Thermosorb-N filters, impingers and PTR-MS were used for sampling. The main objective has been to investigate work environment exposure risk in a CO2 capture plant. The findings show that the median outdoor background concentration during the different test campaigns have been 0.2 ng/m3(Arithmetic Mean 5.8 ng/m3, range <0.01 - 39 ng/m3). The average and maximum concentration represents 3% and 20% of the given Occupational Exposure Limit Value of 200 ng/m3 for NDMA, respectively. Our results suggest that Nitrosodimethylamine can be present at an amine-based CO2-capture test plant, but at acceptable concentrations. In conclusion, the design and operational conditions at Technology Centre Mongstad maintain exposure background levels for the working atmosphere at a satisfactory level.

Energy Performance Analysis of Post-combustion Carbon Capture using Piperazine for Large-scale Natural Gas Combined Cycle Power Plants

Post-combustion carbon capture (PCC) via chemical absorption has the potential to reduce CO2 emission significantly. The main challenges to this technology include the high energy consumption and high capital and operating costs. Alternative process configurations and new solvents are being pursued to reduce the energy consumption process. In this study, the rate-based model of the PCC process using piperazine (PZ) was developed in Aspen Plus® V8.4. The model was validated at pilot scale with experimental data. The model correctly predicted the CO2 capture level, rich loading and reboiler duty measured in the pilot plants. The validated model was scaled up to a PCC plant capable of processing flue gas from a 250 MWe natural gas combined cycle (NGCC) power plant. Three different configurations of the large-scale PCC process using 30-40 wt% PZ were simulated and the energy consumption was evaluated to determine which combination of configuration and solvent gives the best energy performance. The energy performance of the PCC process using PZ was also compared to the standard process using 30 wt% monoethanolamine (MEA) solvent. A regeneration energy of 4.97 GJ/tonneCO2 was obtained for the PCC process with 30 wt% MEA. Compared to the lowest regeneration energy obtained using the standard PCC process with PZ, the regeneration energy reduces by 35%, 41%, and 45% respectively for 30, 35 and 40 wt% PZ concentrations. The minimum regeneration energy of 2.41 GJ/tCO2 was achieved with the advanced flash stripper (AFS) process using 40 wt% PZ.

Cost Reduction Study for MEA based CCGT Post-Combustion CO &lt;sub&gt;2&lt;/sub&gt; Capture at Technology Center Mongstad

A campaign was carried out by Technology Center Mongstad (TCM) and its owners in the amine capture plant to study various cost saving operating options relevant for combined cycle gas turbine plants. The owners chose MEA as solvent for this test because it is a well-studied solvent system with no commercial constraints regarding sharing of data. Learnings obtained from MEA studies are also expected to be of relevance for other solvent systems. During this campaign the main focus was on thermal energy optimization at different flue gas flow rates through the absorber column and MEA emissions, with target for reduced CAPEX and OPEX. During the campaign, new options such as a rich solvent bypass to stripper overhead and higher concentration of MEA (up to 38wt%) were tested. Tests were carried out to identify plant configurations and process parameters with the potential for CAPEX and OPEX reduction in a post-combustion carbon capture plant. Significant cost of CO2 avoided reductions were achieved compared to the previous TCM campaigns for MEA.

Best practices for the measurement of 2-amino-2-methyl-1-propanol, piperazine and their degradation products in amine plant emissions

We herein present the chemical-analytical setup used to measure atmospheric emissions of amines and amine degradation products from an amine-based post-combustion carbon capture plant. The emission measurements were carried out at the Technology Centre Mongstad (TCM) in Norway, in the frame of the ALIGN-CCUS campaign from September 2019 to January 2020, when the amine plant was operated with the CESAR 1 solvent. This advanced solvent is an aqueous solution of 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ). Four chemical-analytical techniques were deployed for characterizing emission of AMP, PZ and their degradation products: online Fourier Transform Infrared (FTIR) Spectroscopy, online Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS), online Proton-Transfer-Reaction Quadrupole Mass Spectrometry (PTR-QMS), as well as manual impinger sampling followed by offline Ion Chromatography Mass Spectrometry (IC-MS) analysis. AMP was detected by all four methods, with the results being in reasonably good agreement. PZ was detected by PTR-TOF-MS, PTR-QMS and IC-MS, but because of the low emission levels (single-digit ppb) the latter two methods suffered from a positive bias (due to an interfering compound) and a large measurement uncertainty, respectively. 17 amine degradation products were only detected by the PTR-ToF-MS analyzer. We present exemplary results from the emission measurements carried out during the ALIGN-CCUS 2019-2020 campaign and share some of the lessons learned from this exercise.

Theoretical comparison between post-combustion carbon capture technology and the use of blue and green H2 in existing natural gas combined cycles as CO2 mitigation strategies: A study under the context of mexican clean energy regulation

The objective of this work is to compare the theoretical implementation of three strategies for reducing CO2 emissions in existing natural gas combined cycles (NGCC) under the context of the Mexican clean energy regulation, namely: NGCC with post-combustion carbon capture plant (CCS); NGCC fueled with blends of natural gas and blue H2 (bH2) or green H2 (gH2). These options were analysed from the point of view of the end users in meeting the National goals in clean electricity generation during the period of 2020–2050. A techno-economic analysis was performed by considering different variables, such as clean energy certificate price, fuel costs, capital expenditure, operating cost and capacity factor plant. In general, the CCS shows a better economic performance than bH2 and gH2 cases for reducing carbon emissions in existing NGCCs. In a low natural gas price scenario ($1/MMBTU), the gH2 case is economically attractive from gH2 cost equal to or less than $ 0.9 per kg. Finally, it is found that under the current Mexican regulatory framework is not possible the incorporation of any of the technologies mentioned above, in which case, this regulation needs to be deeply amended in order to define new technical and administrative criteria for promoting the market entry of these technologies in the country.

Techno-economic analysis of solar-assisted post-combustion carbon capture to a pilot cogeneration system in Mexico

This research evaluates the integration of solar-assisted post-combustion carbon capture into an experimental cogeneration system. A cogeneration system modelled in Thermoflex 25® that includes a 200 kW Capstone microturbine coupled with a thermal oil recovery system was installed at the National Institute of Electricity and Clean Energies (INEEL). Three optimized systems were considered for the economic analysis, namely: a microturbine cogeneration system (COGEN), a microturbine cogeneration system with post-combustion carbon capture plant (COGEN-CCS) and a microturbine cogeneration system with solar-assisted post-combustion carbon capture (COGEN-CCS + SOLAR). The cogeneration system was modelled using Natural Gas (NG) as fuel, applying characteristics typical of Mexico, to obtain the composition of exhaust gas (EG), and thus simulate the CO2 capture system in Aspen Hysys V8.6® using monoethanolamine (MEA) as solvent. Results show that the implementation of CCS results in a sizeable increase in the Levelized Cost Of Electricity (LCOE) (approximately 86%) with near-zero emissions and without the possibility of supplying energy to the process. In addition COGEN-CCS + SOLAR improves overall system performance. CO2 emissions per kilowatt increased by 0.2% with regard to COGEN-CCS, while the LCOE increased by 230% compared to the COGEN case, with near-zero emissions. The use of solar energy would help increase the cogeneration efficiency when coupled with CO2 capture.

A compact and easy-to-use mass spectrometer for online monitoring of amines in the flue gas of a post-combustion carbon capture plant

We herein report on the adaptation and deployment of a compact and easy-to-use mass spectrometer for online monitoring of amines in industrial flue gas at ppb to ppm levels. The use of ammonia as a source gas in proton-transfer-reaction mass spectrometry (PTR-MS) greatly simplifies the detection of amines, making it possible to use a low-end commercial instrument version (PTR-QMS 300) for the measurements. We characterized the analytical performance of the instrument (sensitivity, limit of detection, precision, matrix effects) for nine solvent amines (monoethanolamine, dimethylaminoethanol, aminomethylpropanol, methyldiethanolamine, diglycolamine, piperazine, aminoethylpiperazine, methylpiperazine, N-(2-hydroxyethyl)piperazine) and three degradation amines (methylamine, dimethylamine, trimethylamine). The new analyzer was tested and validated in side-by-side measurements with established emission monitoring techniques at the Technology Centre Mongstad (TCM) in Norway. After validation, the instrument was permanently installed on top of the absorber tower to deliver real-time amine emission data to the plant information management system.

Application of piece-wise linear system identification to solvent-based post-combustion carbon capture

Solvent-based post-combustion carbon capture (PCC) is currently the most promising method to reduce CO2 emission. To achieve a plant-wide controller for flexible operation, it is necessary to develop a data-driven model to understand the dynamic characteristics of PCC plant. This paper aims to: (i) carry out system identification to develop a data-driven model and (ii) provide insights into the nonlinear dynamics among the key variables from the PCC process in a wide operating range. These key variables include: CO2 capture rate, reboiler temperature, condenser temperature and lean solvent temperature. Pilot-scale PCC process implemented in gCCS was used to generate simulation data for system identification and model comparison. Linear single-input-single-output (SISO) transfer function models were firstly developed at different capture rates. Open loop step tests on identified models were then introduced to report the dynamics of key variables in various operating conditions and to indicate the level of system nonlinearity graphically. The nonlinearity analysis was carried out to investigate the system nonlinearity distribution in a quantitative manner. Based on the nonlinearity analysis, a multi-input-multi-output (MIMO) piece-wise model was proposed to simulate the nonlinear characteristics of PCC plant. The piece-wise model shows a satisfactory agreement with gCCS simulation data. Results of this study successfully demonstrate the nonlinear behavior of the solvent-based PCC process, which can be applied in the design of flexible plant-wide controllers.

Integrating geothermal into coal-fired power plant with carbon capture: A comparative study with solar energy

A new system integrating geothermal energy into post-combustion carbon capture is proposed in this paper. Geothermal energy at medium temperatures is used to provide the required thermal heat for solvent regeneration. The performance of this system is compared with solar assisted carbon capture plant via technical and economic evaluation. A 300 MWe coal-fired power plant is selected as the reference case, and two different locations based on the local climatic conditions and geothermal resources are chosen for the comparison. The results show that the geothermal assisted post-combustion carbon capture plant has better performances than the solar assisted one in term of the net power output and annual electricity generation. The net plant average efficiency based on lower heating value can be increased by 2.75% with a thermal load fraction of about 41%. Results of economic assessment show that the proposed geothermal assisted post-combustion carbon capture system has lower levelized costs of electricity and cost of carbon dioxide avoidance compared to the solar assisted post-combustion carbon capture plant. In order to achieve comparative advantages over the reference post-combustion carbon capture plant in both locations, the price of solar collector has to be lower than 70 USD/m2, and the drilling depth of the geothermal well shall be less than 2.1km.

Analysis of di-methyl ether production routes: Process performance evaluations at various syngas compositions

This paper investigates direct di-methyl ether (DME) production based on dry methane reforming (DMR-to-DME) and on bireforming (BiR-to-DME). Technically, DMR-to-DME is preferred to BiR-to-DME because the former produces synthesis gas (syngas) with a hydrogen to carbon monoxide molar ratio (H2/CO) of 1 which is the ideal ratio for DME synthesis. Whereas the latter produces a H2/CO close to 2 and consequently suffers from two apparent drawbacks: (1) lack of the so-called ‘synergy effect’ – a feature that enhances DME yield when operating at H2/CO close to 1, and (2) generation of a high heat capacity by-product (H2O) which makes DME recovery energy intensive. In this paper, we find that those two disadvantages actually enhance the performance of BiR compared to DMR across a range of performance metrics. Although the presence of water increases the cooling/heating duty and the distillation columns’ reboiler duty in the BiR route, more heat released from DME synthesis reactor can be utilized in the reboilers to make BiR techno-economically compatible. To assess the sustainability of DMR and BiR, evaluations are carried out against an existing industrial scale DME production route (auto-thermal-reforming (ATR)). By utilizing the carbon in the CO2 from an attached post-combustion carbon capture plant, DMR and BiR can save 22.3% methane feed uptake on average compared to the ATR process, which results in the DMR and BiR reducing CO2 emissions by at least 6.5% on average.

Highly integrated post-combustion carbon capture process in a coal-fired power plant with solar repowering

While post-combustion carbon capture (PCC) technology has been considered as the ready-to-retrofit carbon capture solution, the implementation of the technology remains hampered by high costs associated with the large energy penalty incurred by solvent regeneration. This paper presents a highly integrated PCC process for a coal-fired power plant with solar repowering that features significantly enhanced energy efficiency. Validated process models are developed for the power, capture, and solar thermal plants and simulated in a model superstructure to evaluate the possible improvements in power plant energy efficiency and power output penalty reductions. A 660-MW power plant is taken as the case study. Three cases are used in this simulation analysis: (a) base case consisting of 660-MW power plant integrated with a PCC plant, (b) the base case extended to incorporate solar repowering, and (c) a highly integrated case that extends on the previous case to include CO2 gas compression unit heat integration. This study also highlights and discusses the role and interaction of various PCC and solar plant variables (e.g., solar field size, steam extraction flow rate, and twin LP turbine pressures) in the integration with power plant parameters. In particular, the power plant deaerator conditions play an important role in determining the total solar thermal energy required from the solar plant, thus dictating the solar field size. Copyright © 2015 John Wiley & Sons, Ltd.

Flexible dynamic operation of solar-integrated power plant with solvent based post-combustion carbon capture (PCC) process

This paper examines flexible operation of solvent-based post-combustion carbon capture (PCC) for the reduction of power plant carbon emissions while minimizing revenue loss due to the reduced power plant electricity output. The study is conducted using a model superstructure enveloping three plants; a power plant, a PCC plant and a solar thermal field where the power plant and PCC plant are operated flexibly under the influence of hourly electricity market and weather conditions. Reduced (surrogate) models for the reboiler duty and auxiliary power requirement for the carbon capture plant are generated and applied to simulate and compare four cases, (A) power plant with PCC, (B) power plant with solar assisted PCC, (C) power plant with PCC and solar repowering – variable net electricity output and (D) power plant with PCC and solar repowering – fixed net electricity output. Such analyses are conducted under dynamic conditions including power plant part-load operation while varying the capture rate to optimize the revenue of the power plant. Each case was simulated with a lower carbon price of $25/tonne-CO2 and a higher price of $50/tonne-CO2. The comparison of cases B–D found that optimal revenue generation for case C can be up to 42% higher than that of solar-assisted PCC (case B). Case C is found to be the most profitable with the lowest carbon emissions intensity and is found to exhibit a constant capture rate for both carbon prices. The optimal revenue for case D is slightly lower than case C for the lower carbon price ($25/tonne-CO2) while it is considerably lower in the higher carbon price ($50/tonne-CO2) scenario. The highest revenue to electricity ratio is found to be for the case where solar repowering is used for power boosting. This study highlights the significant potential of dynamic flexible operation toward deeper reductions in carbon capture costs. This analysis is based on the presence of a carbon pricing scheme currently not present in the Australian market, but which could be realised in the future.

Integration of solar energy in coal-fired power plants retrofitted with carbon capture: A review

This paper reviews the utilization of solar thermal energy technology in assisting coal-fired power plants retrofitted with post-combustion carbon capture (PCC). The focus is on compensating the so-called ‘energy penalty’ imposed on the power plant output by the introduction of PCC plant operations. The integration of solar thermal energy can offset the power plant output reduction due to the PCC installation by totally, or partially providing the energy requirement of the carbon capture plant. The main process integration approaches proposed in this regard are reviewed; their advantages and drawbacks are discussed considering technical and climatic factors. The paper also discusses the merits of this hybridization of power, capture and solar plants as a transition solution for future low-carbon power generation.

Potential for solar-assisted post-combustion carbon capture in Australia

A techno-economic analysis has been performed for a coal-fired power plant retrofitted with Solvent-based Post-combustion Carbon Capture (PCC) technology which is partially supplied with thermal energy by solar thermal collectors. The plant is compared with a generic PCC plant where all the thermal energy is provided by steam bled from the steam cycle. The individual merits of a suite of solar collector technologies which includes Flat Plate Collectors (FPCs), Compound Parabolic Collectors (CPCs), Linear Fresnel Collectors (LFCs), Evacuated Tube Collectors (ETCs) and Parabolic Trough Collectors (PTCs) to supply thermal energy for the PCC plant have been studied. The plant has been simulated for three different locations in Australia: Sydney, Townsville and Melbourne. The overall system consists of three subsystems: power plant, PCC plant and solar collector field. A base case scenario is studied in which there is no heat integration between the three subsystems and is compared to a system with heat integration. Additionally incentives such as Renewable Energy Certificates (RECs), carbon tax/credits and government subsidies have been added to the economic model and a sensitivity analysis performed for each scenario of incentives for all five solar collector technologies at the three locations. The ETC case performs best amongst solar collectors when the three subsystems have heat integration while PTCs perform best in the case with no heat integration. The best location for the solar-assisted PCC (SPCC) plant is Townsville. It was found that the addition of the solar field reduces the carbon tax in order to make carbon capture and storage viable in comparison with a conventional non-capturing coal fired plant.

Optimal Operation of Solvent-based Post-combustion Carbon Capture Processes with Reduced Models

This paper addresses the development of a methodology for optimal operation of solvent-based post-combustion carbon capture (PCC) with respect to techno-economical objectives. One of the main limitations in techno- economical analyses of PCC process is the unavailability of simple models for ease of use in PCC process optimization. Such mathematical models, even in reduced form, could facilitate performing efficient techno- economical studies without dealing with the complex physico-chemical models. In this study, a flowsheet PCC process model is developed and a sensitivity analysis is carried out around 1700 case studies. The resulting data were then modeled with Response Surface Methodology (RSM) to develop an explicit nonlinear reduced model. Optimal operating conditions were then found through the reduced model. Such optimal values are proposed as control set points in the PCC plant.

On-line monitoring and controlling emissions in amine post combustion carbon capture: A field test

The study presents pioneering on-line emission data from a PCCC (post combustion carbon capture) pilot plant of both inorganic and organic components measured using an extractive FTIR (Fourier Transform Infra Red) system. A comparison with other emission measurements allowed concluding that the system is suitable as research tool for investigating the effect of PCCC operational settings on amine emissions. However, it also showed that sampling and analysing single organic components in flue gases is difficult and more research is needed on this topic. Linking the operational data of the plant with the on-line emission data identified two important operational settings that control the amine emissions from a PCCC plant to a large extent: (i) flue gas temperature at the top of the absorber (downstream of the washing section) and (ii) flue gas temperature difference over the washing section. A positive correlation between NH3 emission and the O2 content entering the pilot plant suggests that oxidative degradation occurs. The study emphasizes the importance of a well-designed washing section (if necessary, multi stage) which will be able to reduce emissions to very low levels keeping in mind the lessons learned in this study with respect to its operational settings. Therefore, the knowledge obtained within this research project will be of great use for the future post combustion carbon capture demo and full-scale installations.