INVESTIGATION, SIMULATION AND COMPARISON OF VARIOUS ROUTES FOR BIOETHANOL PRODUCTION

Bioethanol has proven its value as an alternative fuel to gasoline, in fact, more as an adding than a competitor. Bioethanol has attracted a lot of interest due to its biodegradable nature, low cost, low toxicity and safety. The present work is focused on process modelling and simulation of bioethanol production using biomass and / or CO2 and H2 as raw-materials. The first scenario investigated considers the biomass fermentation, the second scenario considers the thermo-catalytic hydrogenation of CO2 while the combination of the previously methods was assumed in the third scenario. The main advantages of these routes are the reduction of greenhouse gas emissions and the production of one valuable chemical, bioethanol. A productivity of 30,000 tones/year of bioethanol is set for all three cases. Purities, higher than 90% for the main product, are obtained. The technical comparison of the three scenarios leads to the conclusion that the best option to obtain bioethanol is from cellulosic biomass. In this first case, the energy consumption is 0.08 kW / kg bioethanol and the carbon dioxide emissions are 0.96 kg CO2 / kg bioethanol being much lower than in the other two considered cases

ASSESSMENT OF FLEXIBLE CARBON CAPTURE AND UTILIZATION OPTIONS APPLIED TO GASIFICATION PLANTS

The aim of this work is to assess the energy vector poly-generation capabilities of gasification plants equipped with carbon capture and utilization (CCU) features. As evaluated energy carriers, various total or partial decarbonized vectors were investigated (e.g., power, hydrogen, synthetic natural gas, methanol, Fischer-Tropsch fuel). As illustrative examples, the gasification concepts with 100 MW net energy output were considered having an overall plant decarbonization rate of 90%. As decarbonization technologies, the gas – liquid absorption based on chemical and physical scrubbing was assessed. A broad range of process system engineering tools were used (e.g., modeling and simulation, process integration, plant flexibility elements, technical and environmental evaluation). As results show, the application of carbon capture and utilization technologies for gasification-based poly-generation has promising results in term of increasing the overall energy efficiency (up to 68%), reducing CO2 emissions (down to 7 kg/MWh) and improving cycling capabilities

AN ENVIRONMENTAL ASSESSMENT OF ENERGY STORAGE USING THE RESTORE CONCEPT: ANALYSIS OF THE GMUNDEN CEMENT PLANT

The RESTORE initiative explores an innovative method of energy storage based on the thermochemical cycling of copper sulphate. During periods of surplus renewable electricity, such as for example solar-rich summer months, the system stores energy through the dehydration of copper sulphate. The stored energy is subsequently recovered during colder periods, such as winter, when energy demand increases and renewable availability declines, via the rehydration of the material. The current investigation focuses on the industrial RESTORE application at the Gmunden cement plant in Austria, proposing the integration of Thermochemical Energy Storage (TCES) with an Organic Rankine Cycle (ORC) and a Heat Pump (HP). The sustainability of the system was evaluated through a Life Cycle Assessment (LCA), conducted in accordance with the standard LCA framework, using version 10.8 of the LCA for Experts software. Environmental performance was quantified based on eleven key indicators derived from the ReCiPe 2016 assessment method. The functional unit for this study was set as the generation of 1 kWh of thermal energy, enabling a consistent comparison between the two construction alternatives of storage tanks, relevant to the industrial use case: carbon steel against high-density polyethylene (HDPE). The system boundaries were established to encompass the complete life cycle, segmented into three primary stages: i) Upstream activities; ii) Core operational processes; iii) Downstream operations. The use of HDPE outperformed carbon steel in key impact categories, cutting global warming potential (GWP) by over 55%, while significantly lowering other indicators. However, increased impacts in terms of fossil depletion and freshwater ecotoxicity potential are registered, likely due to the petroleum-based nature of HDPE. Several discussions and interpretations of the most relevant environmental key performance indicators are provided, underlining the effectiveness of the proposed concepts

MODELLING AND SIMULATION OF FUELS PRODUCTION FROM SYNGAS

Syngas is a very important product, with a variety of uses; it may even become a primary source of fuel, and replace natural gas. This is because syngas has the building blocks to create all the products and chemicals currently generated in the petrochemical industry. Fuels manufactured from synthesis gas offer special opportunities based both on environmental and energy performance. The aim of the present work is to design and compare different chemical production processes for fuels generation using syngas as raw material. ChemCAD process simulator software was used as the main tool for process modelling and simulation. The investigation was focused on the conversion of syngas to methanol, dimethyl ether and hydrogen at a large scale. For comparison reasons, the same amount of syngas (e.g. 10000 kmol/h) was used in all three cases under investigation. After comparison, syngas to hydrogen process seems to be the best option from thermal energy point of view and in terms of environmental impact

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

Comparison Of Membrane-Based Pre- And Post-Combustion CO2 Capture Options Applied In Energy-Intensive Industrial Applications

Deployment of decarbonization technologies in energy-intensive industrial applications (e.g., heat and power, metallurgy, cement, chemical sectors etc.) is of great importance for reducing CO2 emission and achieving global climate neutrality. Membrane CO2 removal systems gained relevant attention as possible energy and cost-efficient CO2 capture technology. This paper is evaluating membrane-based pre- and post-combustion CO2 capture to be applied in various industrial applications with high fossil CO2 emissions. The evaluation was geared mainly towards quantification of ancillary energy consumptions of membrane systems as well as the specification of captured CO2 in respect to its potential utilization and storage applications. As the assessment show, the membrane-based systems are promising CO2 capture technology for both pre- and post-combustion capture configurations.publishedVersio

Evaluation of Calcium Looping as Carbon Capture Option for Combustion and Gasification Power Plants

AbstractPower generation is one of the industrial sectors with major contribution to greenhouse gas emissions (especially CO2). For climate change mitigation, a special attention is given to the reduction of CO2 emissions by applying capture and storage techniques in which CO2 is captured from energy-intensive processes and then stored in suitable safe geologic locations. Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for curbing the greenhouse gas emissions and to ensure a sustainable development of power generation and other energy-intensive industrial sectors (e.g. cement, metallurgy, petro-chemical etc.). Among various carbon capture options, chemical looping systems are very promising options for intrinsically capture CO2 with lower cost and energy penalties.This paper evaluates calcium looping process as a promising carbon capture option to be applied in the most important coal- based power generation technologies. Combustion technology (Pulverized Fuel - PF) operated in both sub-critical and super- critical steam conditions were evaluated. Also, the gasification technology using an oxygen-blown entrained-flow gasifier was evaluated. As benchmark options, the same power generation technologies were evaluated without CCS. The power plant case studies investigated in the paper produces around 545 – 560 MW net power with at least 90% carbon capture rate. The modeling and simulation of the whole power generation schemes produced the input data for quantitative technical and environmental evaluations of power plants with carbon capture (similar power plant concept without CCS was used as reference for comparison). Mass and energy integration tools were used to assess the integration aspects of calcium looping unit into the whole power plant design, to optimize the overall efficiency and to evaluate the main sources of energy penalty for carbon capture

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)