Carbon Dioxide Capture in the Iron and Steel Industry: Thermodynamic Analysis, Process Simulation, and Life Cycle Assessment

The iron and steel sector is one of the dominant drivers behind economic and social progress, but it is also very energy-intensive and hard-to-abate, making it a major cause of global warming. Improving energy efficiency, introducing hydrogen for direct reduction, and utilising CCS technologies are the three most viable options for reducing CO2 emissions from steel mills. This investigation deals with a life cycle comparison of three different carbon capture processes, the inventory data of which have been obtained using process simulation based on rigorous phase and chemical equilibrium equations. In-silico models for the absorption of carbon dioxide employing MDEA, membranes, or sodium hydroxide to produce sodium bicarbonate have been developed and compared from a life cycle viewpoint. The research findings showed a variable amount of CO2 removal in the three cases, where membranes achieved the best performance (95 % CO2 removal). Since NaOH absorption produces a valuable by-product (sodium bicarbonate, which is commonly produced by Solvay process), the other two technologies were modified to integrate the utilisation of CO2 for the synthesis of sodium bicarbonate with NaOH rather than transporting and storing the carbon dioxide. As a result, this production pathway for sodium bicarbonate generates lower environmental burdens than traditional Solvay process. The environmental performances of the alternatives are nearly equal, even though the environmental impacts associated with capturing the CO2 and subsequently reacting with NaOH are always slightly higher than those involved with reacting directly during absorption. Among the evaluated alternatives, the direct conversion to sodium bicarbonate appears to be the most promising approach for converting CO2 emissions in the steel sector

Comparative study on certain parameters of the skull of some cats species grown in captivity in Romania

In Romania, 5 of the 6 species covered by this study - tiger (Panthera tigris), lion (Panthera leo), jaguar (Panthera onca), cheetah (Acinonyx jubatus) and puma (Puma / Felis concolor) - are present only in circuses or zoos, and the sixth species - the European wildcat (Felis silvestris silvestris) is present in our country in wild. The studied specimens were born and bred in captivity and have slightly smaller dimensions than wild specimens. The skulls come from the Anatomy museum, Faculty of Veterinary Medicine in Bucharest. There are not known the subspecies of tiger, lion, jaguar, cheetah or cougar from which the skulls belonged. The bodies of these cats that died of natural causes (old age) were donated by Bucharest-Baneasa Zoo and Circus N & Variete Globus Bucharest (cheetah and one tiger). Our measurements are based on studies conducted on wild cat skulls by Clara Stefen D. Heidecke (2012) and skulls of several species of mammals from archaeological sites by Angela von den Driesch (1976). Based on the measurements, the facial index, the cranial index, the skull volume, and the cranial cavity volume were calculated. It was observed that only the tiger and the wild cat facial and cranial indexes are close, while for the other species the facial index is higher than the head one. The biggest difference between the volume of the skull and cranial cavity volume is observed in tiger, and the smallest difference at the wildcat. Even if they are part of different kinds of cats, the cheetah (big cats category) and the puma (small cats category) presented similar values for the cranial cavity and cranial volume area

Classical and Process Intensification Methods for Acetic Acid Concentration: Technical and Environmental Assessment

This study aims to investigate, from a technical and an environmental perspective, various alternatives for acetic acid concentration for maximizing acetic acid production, its purity, and in the meantime, minimizing the energy usage and the environmental impact. Liquid–liquid extraction followed by azeotropic distillation using different solvents such as: (i) ethyl acetate, (ii) isopropyl acetate, and (iii) a mixture containing isopropyl acetate and isopropanol were first explored, using process flow modeling software. The three cases were compared considering various technical key performance indicators (i.e., acetic acid flow-rate, acetic acid purity, acetic acid recovery, power consumption, thermal energy used, and number of equipment units involved) leading to the conclusion that the usage of the isopropyl acetate—isopropanol mixture leads to better technical results. The isopropanol-isopropyl acetate mixture was furthermore investigated in other two cases where process intensification methods, based on thermally coupled respectively the double-effect distillation process, are proposed. The highest quantity of pure acetic acid (e.g., 136 kmol/h) and the highest recovery rate (e.g., 97.74%) were obtained using the double-effect method. A cradle-to-gate life cycle assessment, involving ReCiPe method, was used to calculate and compare various environmental impact indicators (i.e., climate change, freshwater toxicity potential, human toxicity, etc.). Several steam sources (i.e., hard coal, heavy fuel oil, light fuel oil, natural gas, and biomass) were considered in the environmental evaluation. The results of the life cycle assessment show a reduction, by almost half, in all the environmental impact indicators when the double effect method is compared to the thermally coupled process. The usage of biomass for steam generation lead to lower impacts compared to steam generation using fossil fuels (i.e., hard coal, heavy fuel oil, light fuel oil, natural gas)

Life Cycle Assessment for supercritical pulverized coal power plants with post-combustion carbon capture and storage

Environmental and technical aspects of four supercritical (SC) pulverized-coal processes with post-combustion carbon capture and storage (CCS) are evaluated in the present work. The post-combustion CCS technologies (e.g. MDEA, aqueous ammonia and Calcium Looping (CaL) are compared to the benchmark case represented by the SC pulverized coal without CCS). Some important key performance indicators (e.g. net electrical power, energy conversion efficiency, carbon capture rate, specific CO2 emissions, SPECCA) are calculated based on process modeling and simulation data. The focus of the present work lies in the environmental evaluation, using the Life Cycle Analysis (LCA) methodology, of the processes considered. The system boundaries include: i) power production from coal coupled to energy efficient CCS technologies based on post-combustion capture; ii) upstream processes such as extraction and processing of coal, limestone, solvents used post-combustion CCS, as well as power plant, coal mine, CO2 pipelines construction and commissioning and iii) downstream processes: CO2 compression, transport and storage (for the CCS case) as well as power plant, CCS units, coal mine and CO2 pipelines decommissioning. GaBi6 software was used to perform a “cradle-to-grave” LCA study, to calculate and compare different impact categories, according to CML 2001 impact assessment method. All results are reported to one MWh of net energy produced in the power plant. Discussions about the most significant environmental impact categories are reported leading to the conclusions that the introduction of the CCS technologies decreases the global warming potential (GWP) indicator, but all the other environmental categories increase with respect to the benchmark case. There is also a competition between the aqueous ammonia adsorption and CaL for some impact categories (other than GWP). The implementation of these new CCS technologies is more favorable than the traditional amine-based CO2 capture

Life Cycle Assessment of Natural Gas-based Chemical Looping for Hydrogen Production

AbstractHydrogen production from natural gas, combined with advanced CO2 capture technologies, such as iron-based chemical looping (CL), is considered in the present work. The processes are compared to the conventional base case, i.e. hydrogen production via natural gas steam reforming (SR) without CO2 capture. The processes are simulated using commercial software (ChemCAD) and evaluated from a technical point of view considering important key performance indicators such as hydrogen thermal output, net electric power, carbon capture rate and specific CO2 emissions. The environmental evaluation is performed using Life Cycle Analysis (LCA) with the following system boundaries considered: i) hydrogen production from natural gas coupled to CO2 capture technologies based on CL, ii) upstream processes such as: extraction and processing of natural gas, ilmenite and catalyst production and iii) downstream processes such as: H2 and CO2 compression, transport and storage. The LCA assessment was carried out using the GaBi6 software. Different environmental impact categories, following here the CML 2001 impact assessment method, were calculated and used to determine the most suitable technology. Sensitivity analyses of the CO2 compression, transport and storage stages were performed in order to examine their effect on the environmental impact categories

Techno-Economic and Environmental Evaluations of Decarbonized Fossil-Intensive Industrial Processes by Reactive Absorption & Adsorption CO2 Capture Systems

Decarbonization of energy-intensive systems (e.g., heat and power generation, iron, and steel production, petrochemical processes, cement production, etc.) is an important task for the development of a low carbon economy. In this respect, carbon capture technologies will play an important role in the decarbonization of fossil-based industrial processes. The most significant techno-economic and environmental performance indicators of various fossil-based industrial applications decarbonized by two reactive gas-liquid (chemical scrubbing) and gas-solid CO2 capture systems are calculated, compared, and discussed in the present work. As decarbonization technologies, the gas-liquid chemical absorption and more innovative calcium looping systems were employed. The integrated assessment uses various elements, e.g., conceptual design of decarbonized plants, computer-aided tools for process design and integration, evaluation of main plant performance indexes based on industrial and simulation results, etc. The overall decarbonization rate for various assessed applications (e.g., power generation, steel, and cement production, chemicals) was set to 90% in line with the current state of the art in the field. Similar non-carbon capture plants are also assessed to quantify the various penalties imposed by decarbonization (e.g., increasing energy consumption, reducing efficiency, economic impact, etc.). The integrated evaluations exhibit that the integration of decarbonization technologies (especially chemical looping systems) into key energy-intensive industrial processes have significant advantages for cutting the carbon footprint (60–90% specific CO2 emission reduction), improving the energy conversion yields and reducing CO2 capture penalties

Life Cycle Assessment of SEWGS Technology Applied to Integrated Steel Plants

The environmental evaluation of the sorption-enhanced water–gas shift (SEWGS) process to be used for the decarbonization of an integrated steel mill through life cycle assessment (LCA) is the subject of the present paper. This work is carried out within the STEPWISE H2020 project (grant agreement No. 640769). LCA calculations were based on material and energy balances derived from experimental activities, modeling activities, and literature data. Wide system boundaries containing various upstream and downstream processes as well as the main integrated steel mill are drawn for the system under study. The environmental indicators of the SEWGS process are compared to another carbon capture and storage (CCS) technology applied to the iron and steel industry (e.g., gas–liquid absorption using MEA). The reduction of greenhouse gas emissions for SEWGS technology is about 40%. For the other impact indicators, there is an increase in the SEWGS technology (in the range of 7.23% to 72.77%), which is mainly due to the sorbent production and transportation processes. Nevertheless, when compared with the post-combustion capture technology, based on gas–liquid absorption, from an environmental point of view, SEWGS performs significantly better, having impact factor values closer to the no-capture integrated steel mill