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Carbon Capture Utilization or Storage (CCUS) has gained widespread attention as an option for reducing CO 2 emissions from power plants but specific developments are still needed for the application to cement plants. More precisely, the post-combustion CO 2 capture process by absorption-regeneration is the more mature technology but its cost reduction is still necessary. The present study is focusing on Aspen Hysys™ simulations of different CO 2 capture process configurations (namely “Rich Solvent Recycle” (RSR), “Solvent Split Flow” (SSF), “Lean/Rich Vapor Compression” (L/RVC)) applied to the flue gas coming from the Norcem Brevik cement plant (taken as case study) and using three different solvents, namely: monoethanolamine (MEA), piperazine (PZ) and piperazine-methyldiethanolamine (MDEA) blend. For each configuration and solvent, different parametric studies were carried out in order to identify the operating conditions ((L/G) vol. , split fraction, flash pressure variation, etc.) minimizing the solvent regeneration energy. Total equivalent thermodynamic works and utilities costs were also analyzed. It was shown that the configurations studied allow regeneration energy savings in the range 4–18%, LVC and RVC leading to the higher ones. As perspectives, other configurations and combination of configurations will be considered in order to further reduce the energy consumption of the process. [ABSTRACT FROM AUTHOR]

• Process modeling and conceptual design are implemented using Aspen Plus. • Techno-economic and environmental analyses are conducted for performances evaluation. • Thermal energy self-sufficiency is achieved through an optimized integrated process. • Overall energy efficiency reaches 89.5 % on a LHV basis. • Drastic reductions in terms of net CO 2 emissions and fossil depletion are observed. Carbon Capture Utilization and Storage (CCUS) technologies are receiving increasing interest and its implementation at world scale appears to be crucial to reduce CO 2 emissions. In this context, Power-to-Gas technologies (PtG) are very promising, allowing to store renewable electricity and valorize captured CO 2 to produce Synthetic Natural Gas (SNG), among other. The present work simulates an integrated CO 2 capture and conversion process to SNG, and investigates its techno-economic and environmental performances. Different scenarios are defined considering the application to a cement plant flue gas and the production of renewable hydrogen. An advanced CO 2 capture unit is implemented, considering a configuration (Rich Vapor Compression and Inter Cooling) and a solvent (MDEA + PZ) allowing to minimize its specific energy consumption (35 % regeneration energy savings in comparison with a conventional amine-based CO 2 capture system). The excess heat released by the catalytic conversion is recovered for the solvent regeneration maximizing the amount of captured CO 2. From the scenarios analyses, it is shown that integrating the CO 2 capture and conversion steps is beneficial for reducing both the net CO 2 emission to the atmosphere, by 45 %, and the contribution to fossil depletion, by 81 %, in comparison with the non-integrated one, as the production of fossil-based natural gas is replaced by renewable SNG. The proposed process leads to a cost of 2.39 € per kg Raw-SNG, with expected revenues of 0.87 € per kg Raw-SNG. Significant subsidies and incentives would thus be needed to compete with conventional energy prices for natural gas (0.55 € per kg). [ABSTRACT FROM AUTHOR]

• High CO 2 contents flue gases. • Both simple and activated solutions investigated in partial oxy-fuel conditions. • Simulation of absorption-regeneration CO 2 capture process. • Aspen Hysys™ simulations validated thanks to micro-pilot experimental results. • Significant energy savings. The present study is focusing on the investigation, for the cement industry, of the post-combustion CO 2 capture process using amine(s)-based solvents. The novel aspect of the work is the flue gas considered, namely the high CO 2 contents (between 20 and 60 vol.%), representative of flue gases coming from oxygen-enriched air combustion process (also called partial oxy-fuel combustion). Using the results of preliminary solvents screening tests at laboratory scale, absorption-regeneration micro-pilot experiments were carried out for the best solvents in order to characterize their respective absorption and regeneration performances. The use of the activated solution of DEA (diethanolamine) 30 wt.% with PZ (piperazine) 5 wt.% led to particularly high absorption performances in all CO 2 concentration range. Besides the experimental measurements, Aspen Hysys™ simulations of the micro-pilot tests were performed for three solvents (monoethanolamine (MEA) as the reference case, then PZ and DEA + PZ) to validate the models implemented. Finally, the validated models were used to perform industrial scale simulations. These simulations confirmed that both the regeneration energy, the equivalent work and the operating costs are reduced when the absorption-regeneration process is implemented to flue gases with high CO 2 contents. [ABSTRACT FROM AUTHOR]

The carbon capture, utilisation and storage (CCUS) process chain is subject to increasing interest, and its overwhelming implementation on the industrial scale appears to be one of the main ways to reduce CO 2 emissions. In this context, the optimisation of a CO 2 purification process for oxy-combustion cement plant flue gases is proposed. This optimisation is based on a multidimensional study on the energy, exergy, economy, and environmental impacts of the process. The results of the optimisations carried out show that it is more favourable to increase the CO 2 recovery above 90%, from an energy, exergy and economic point of view. The analysis of the evolution of the capture cost as a function of the CO 2 recovery shows that for a given carbon tax, there is a minimum for the total cost which includes the sum of the carbon tax contributions for the uncaptured CO 2 and the capture cost. As the unit uses only electrical energy, the cost and the electricity generation will directly impact the capture cost as well as the overall balance in terms of CO 2 avoided. As the electricity price increases from 50 to 250 €/MWh, the CO 2 capture cost increases by almost 250%. An analysis of the parameter uncertainties allows to observe their impacts on the results, and to define a standard deviation from the optimised points and show the robustness of these. Considering the technical parametric uncertainties, the standard deviation on the electrical consumption (3.65 kWh/t CO2), CO 2 recovery (0.09%) and exergy efficiency (0.92%) is limited. • Study of hybrid CO 2 capture system combining cryogenic and membrane technologies. • 4E analyses considering recovery, energy consumption, exergy yield and capture cost. • Maximum exergy efficiency for the cases where the CO 2 recovery is above 90%. • High sensitivity of the electricity price on the CO 2 capture cost. • Uncertainty quantification of modelling assumptions and impact on 4E analyses. [ABSTRACT FROM AUTHOR]

• Study of hybrid CO 2 capture system combining VPSA and CPU technologies. • Optimization of integrated capture CO 2 process and purification unit. • High CO 2 recovery (90–99 %) and high CO 2 purity (>99.99 %) • Complete analyses considering recovery, energy consumption, and capture cost. • Impact of the electricity source on the total CO 2 recovery. The imperative challenge posed by climate change requires urgent actions to counteract the harmful effects of greenhouse gas emissions, particularly CO 2 , which contributes to approximately 80 % of emissions responsible for global warming. A hybrid system combining Vacuum Pressure Swing Adsorption (VPSA) unit with a Cryogenic Carbon Purification Unit (CPU) is evaluated to enhance recovery and purity of CO 2 captured from flue gas containing CO 2 concentration ranging from 5 % to 20 %. VPSA preconcentrates the CO 2 and CPU completes the separation and purifies the CO 2. The study uses surrogate models for multi-objective optimization, considering energy consumption, cost, and CO 2 recovery, providing a time-efficient approach for investigating computationally demanding processes. Results from the study indicate that the hybrid system achieves over 90 % recovery for flue gas concentration range considered, while ensuring the production of high-purity CO 2 (>99.99 %) suitable for transportation. A trade-off analysis reveals the balance between recovery, electricity consumption, and economic viability. A sensitivity analysis identifies parameters influencing recovery and energy consumption, providing guidance for future optimization efforts. The techno-economic analysis highlights the impact of electricity prices and carbon taxes on total costs, identifying an optimum towards higher recovery values under rising carbon taxes. Furthermore, the research underscores concentration-dependent economic feasibility, emphasizing the attractiveness of concentrations above 10 % compared with other technologies, which require higher concentrations. For an electricity price of 75 €.MWh−1, the total cost of the CO 2 capture hydride system considering CO 2 emissions with carbon tax of 100 €.t CO2 −1 for concentrations ranging from 10 % to 20 % is from 123 to 80 €.t CO2 −1, respectively. The analysis of the electricity source shows the importance of a low-carbon emission energy mix for optimal carbon emission reduction. [ABSTRACT FROM AUTHOR]

Direct Air Capture (DAC) technologies are gaining interest in the concept of carbon utilization and Power-to-Gas (PtG), as the economic valorization of the CO 2 into methane provides a viable pathway to allow DAC systems to mature. However, research on DAC mainly focuses on isolated systems, and the system performance depends on parameters that are highly uncertain. To study the integration of DAC in PtG, we developed a DAC-PtG model, performed an Energy, Exergy, Economic and Environmental (4E) analysis and implemented uncertainty quantification to consider the uncertain environment. The results illustrate that the DAC-PtG system is autothermal when introducing a two-stage mechanical vapor recompression unit at the DAC outlet. The exergy efficiency ranges between 51.3% and 52.6% within 3 standard deviations, for which the uncertainty is driven by the ambient conditions and the uncertain heat of desorption. The methane issued from DAC-PtG has a lower carbon footprint than fossil methane when the carbon footprint of the electricity supply is below or equal to 0.12 kg˙CO˙2-eq /kWh. The Levelized Cost of Synthetic Natural Gas (LCSNG) ranges between 130 €/ MWh and 744 €/ MWh, following an uncertain electricity price and uncertain expenses related to DAC and electrolysis. Therefore, bulk manufacturing, further maturing of these technologies and more demonstration projects are required to reduce the uncertainty of the LCSNG. Future works will consider intermittent renewable energy sources to supply power. • Integrated direct air capture and CO 2 methanation are investigated. • Exergy efficiency ranges between 51.3% and 52.6% within three standard deviations. • The levelized cost of synthetic natural gas ranges between 130 €/MWh and 744 €/MWh. • Electricity emission intensity below 0.12 kg CO2-eq /kWh results in carbon reduction. • To reduce uncertainty, bulk manufacturing and more pilot projects are needed. [ABSTRACT FROM AUTHOR]