The continuous increase in greenhouse gas emissions and the strengthening of environmental regulations have brought Carbon Capture, Utilization, and Storage (CCUS) technology into focus. Most liquefied carbon dioxide carriers (LCO2Cs) employ liquefied natural gas (LNG) propulsion, but they still emit significant greenhouse gases, highlighting the need for further reduction. While boil-off gas (BOG) handling is essential for long-distance LCO2C operations, no studies have examined onboard carbon capture systems (OCCS) integrated with BOG handling systems. This study evaluates five operational cases—BOG re-liquefaction (RLIQ), OCCS, purge gas recapture, and their combinations—to assess the greenhouse gas reduction and economic feasibility of LCO2Cs. Although standalone RLIQ and OCCS showed similar reduction rates (29% and 30%), the avoidance cost of OCCS alone was more than two times higher. Integrating BOG RLIQ, OCCS, and purge recirculation achieved up to 69% well-to-wake emission redu... [more]

To facilitate large-scale green hydrogen production, manufacturers are moving towards pressurized and strongly coupled topologies where multiple electrolyzers share the same processing equipment. This coupling increases the control challenges regarding temperature and safety-critical gas purity constraints. In this paper we develop two advanced regulatory control elements aimed at these constraints and embed them in a plantwide control structure for such systems. We show in dynamic simulations that our approach achieves nearly the same production efficiency as with an explicit optimization layer, while being inherently safer compared to reference control structures. We further show that it can extend the operating limits by up to 50% compared to simpler regulatory control layers, allowing for significant increases in flexibility and thereby profitability in the day-ahead electricity market.

CCS is a well investigated and fairly promising technology for reducing the emission of carbon dioxide (CO2) to the atmosphere. However, it is rarely implemented in the industry due to its high cost. Therefore, this work proposes a cost optimized CCS chain which can be operated flexibly and safely. For the capture process a post combustion chemical absorption technology is chosen due to its retrofitting possibility to already existing power plants and its low capture cost. In order to find a cost efficient absorption process for different scenarios, the five most promising process configurations from previous work are combined into a superstructure in a rigorous rate based reactive Aspen Plus model. This in turn is optimized by a two-stage stochastic programming approach in Matlab. The optimal supply chain network is identified by a tailor made transshipment model implemented in GAMS, which accounts for the most promising transportation units, storage sites as well as direct utilizatio... [more]

For this year’s EURECHA challenge we have made our report with two very different segments in mind. One is technical and is based on verifiable data, calculations and of course computer simulations, while the other segment is more illustrative, and serves only to give better representations. Of course bigger emphasis was put on the technical part. The computer simulations done for technical part of this report cover electrical provision from the light ends of the crude oil, fertilizer production using ammonia, which is produced taking heavy oil as a raw material. Furthermore, water recycling at the refinery and of course provision of potable water for the growing city is also considered. The simulation results showed that using suitable technologies and process integration it is possible to obtain a sustainable development of the Sheikhdom. The illustrative part is basically a city of 20,000 made in a computer game called “CITIES:Skylines”. The game allows the user to import real life... [more]

The escalating urgency to address climate change has driven carbon capture (CC) technologies into the spotlight, particularly for large-scale emitters, which benefit from economies of scale. However, small-scale emitters account for a significant share of CO2 emissions, yet such applications remain largely overlooked in the literature. While CC cost is often used as a key performance indicator (KPI) for CC technologies, the lack of standardized cost estimation methods leads to inconsistencies, complicating comparisons, and hindering the deployment of CC systems. This study addresses these challenges by developing flexible short-cut correlations for selected CC technologies, providing estimates of the total equipment cost (TEC) and energy consumption specific to small-scale applications across various CO2 inlet concentrations (mol%) and capture scales (10 – 100 kt/y). The flexibility of the correlations enables the integration of various cost estimation methods available in the literatu... [more]

Shipping is the backbone of global freight. However, due to its currently strong reliance on fossil fuels, it accounts for 3 % of global greenhouse gas emissions, highlighting both the need and challenge of achieving the required rapid decarbonization. Over the past decade, Onboard carbon capture and storage (OCCS) has gained interest as a potential mitigation strategy while alternative fuels continue to develop. However, several capture technologies could be considered to capture the resulting CO2. In order to identify the most promising ones, this study performs a screening of different capture technologies (including absorption, membrane-assisted liquefaction, adsorption-assisted liquefaction, calcium-looping) through the case of a combination carrier under retrofit and newbuilding scenarios.
Overall, the results indicate that retrofit installations can reduce CO2 emissions by at least 45 %, even when using the existing ship power system. Once the utility (heat and power) is assum... [more]

While he was trapped in a Shell oil refinery for weeks during a 1973 plant strike, Charles R. Cutler (1936-2020) used the opportunity to try out his untested theories on a new method for controlling chemical plants on the actual refinery. They worked spectacularly, and the resulting Dynamic Matrix Control method later became a standard part of control engineering practice. However, DMC was kept a trade secret at Shell until 1980 when it was first made available to the public. This book uncovers the history behind the theory by publishing Cutler’s writings and letters, including his 1969 thesis proposal letter to Prof. Huang at the University of Houston outlining his theories, and a more developed draft paper from 1975 that was never published. Science historians and control engineers alike can trace the development of the theory over time from its earliest origins.

This study introduces a novel and eco-efficient CO2 hydrogenation process design. Following an extensive literature review, Formic Acid (FA) emerged as a viable bulk chemical. A market analysis was performed to estimate feedstock availability. The plant, located in Ravenna, Italy, can produce 50 kta of 85 %wt. FA. The conversion of CO2 and green H2 into FA was meticulously analyzed to identify the best operating conditions and separation technologies, including COPureTM. A key innovation of the sustainable process, simulated in Aspen Plus, is the implementation of Dividing Wall Column (DWC) configuration, which along with heat integration, results in 64% electricity savings, 20% less stream requirements and 51% reduction in CO2 emissions compared to conventional processes. A 2030 economic assessment estimates capital investment and production costs at 73.8 M€ and 41.8 M€/yr respectively, with a profit of 9.5 M€/yr. A sensitivity analysis showed that profitability is heavily impacted by... [more]

Nitrogen-based fertilisers are pivotal for global food security, yet their production is a notable source of greenhouse gas emissions. Urea, a vital fertiliser with significant market presence—19% in Europe and 33% globally—is produced through an energy-demanding process reliant on fossil fuels. This study introduces a ’Green’ Urea plant concept, aimed for implementation in Ravenna, Italy, harnessing exclusively renewable energy sources to foster agricultural sustainability. With a production capacity of 1,300 tonnes per day, this facility neighbours Italy’s first carbon capture and storage (CCS) facility at Ravenna. The core of the proposed methodology is the synthesis of green ammonia. Seawater Reverse Osmosis-Polymer Electrolyte Membrane Electrolysis (SWRO-PEM) and Pressure Swing Adsorption (PSA) yield the necessary hydrogen and nitrogen feedstocks. An enhanced Haber-Bosch process utilising a Ru-based catalyst, facilitating lower operational conditions (500◦C and 100 bar) for the af... [more]

Nowadays, it is crucial to change daily habits to live in a more sustainable world. From an industrial point of view, the capture of CO2 is becoming more and more important in the chemical industry to reduce greenhouse gas emissions and its reuse can be an alternative to fossil resources. Another major challenge for future engineers is the significant increase in the use of renewable energy sources. In this perspective, a process allowing the synthesis of three different olefins from CO2 captured in industrial flue gases and using only wind energy is established. This process is separated into three major sections: water electrolysis, carbon dioxide reduction to produce methanol and methanol-to-olefins synthesis. The targeted production capacity is of 450 000 tonnes per year of olefins, which are considered to be ethylene, propylene and butylene. This process, which involves a complete flowsheet modelling is implemented with the Aspen Plus software. A heat integration is performed to i... [more]

To create useful products from carbon dioxide, electrochemical reduction is of the most promising approaches. Electrochemical reduction can use renewable energy to directly produce useful products such as formic acid, carbon monoxide, methanol or other C2 products. Specifically in Greece, methanol has been proven as a promising alternative for marine fuel, and it has been increasing in demand recently. As such, the proposed design is aimed to target this market. This paper will focus on the production of methanol using direct CO2 electro-reduction using Direct Air Capture (DAC) for the CO2 feed. A mathematical model of the electrolyser was created and implemented in Python. This model was then used alongside renewable energy production data from Open Power Systems [1] to optimise the total annualised cost with the constraint that the plant could only use renewable energy and must produce a minimum methanol flowrate. A combined stochastic search and derivative-free optimisation method w... [more]

The restructuring of the chemical industry towards the use of CO2 and intermittent, renewable energy sources poses a significant challenge for chemical engineers. Based on a systematic screening of current carbon-based chemical processes, we identify a promising combined reversible solid oxide cell (RSOC) and sorption-enhanced DME synthesis (SEDMES) process which produces dimethyl ether from captured CO2 and wind-generated electricity. Existing flowsheet alternatives are researched and a novel process design is proposed and simulated using Aspen Plus® and MATLAB®.
The optimization is divided into a design and a demand side management problem, solved by a genetic algorithm and the linear programming solver CPLEX, to determine the optimal operation and optimal production regime dependent on dynamic renewable electricity availability and price. The thermodynamic, economic, and ecological performance is assessed and compared to a selected fossil based state-of-the-art and biomass based st... [more]

The use of captured CO2 as a raw material is a quite old concept that has however received more and more attention recently. Indeed, carbon capture units are increasingly being developed as well as new technologies for the storage, the utilisation and the transformation of this captured CO2. This is driven by the increasing necessity to move towards more sustainable production processes and to mitigate greenhouse gases emissions.
The storage of CO2 in earth’s layers being a cost only technology, the alternative consisting in the production of novel chemical products or key substitutes to fossil-based chemicals seems attractive. In this perspective, two processes for dimethyl carbonate (DMC) production from captured CO2 are discussed. The selected pathways both differ from usual dimethyl carbonate units in the selected raw materials and in the choice of energy used. Both processes rely on the direct synthesis of DMC from methanol and carbon dioxide. Each implies the utilisation of a de... [more]

Vaccines are typically produced in large facilities to take advantage of economies of scale. However disease outbreaks are often local in nature and require flexible, small-scale production, especially in regions with poor infrastructure. In this work, mobile on-demand vaccine production is explored as a solution to future outbreaks. An mRNA vaccine process is scaled down to the size of two 20-foot shipping containers, so that 10,000 vaccine doses can be produced in one batch in less than 16 hours. The container is self-sufficient except for the regular resupply of water and electricity being able to produce 100 batches without resupply raw materials and consumables. The final cost per dose is estimated to be 25 e with a likely range between 4 to 45 e depending on dose size, raw material prices, and other underlying assumptions. The practicality of a container-based facility at the presented scale is demonstrated by two case studies.

Replacing fossil resources with green hydrogen in industrial production holds tremendous potential for greenhouse gas mitigation. The economic feasibility and greenhouse gas (GHG) mitigation of grid-based electrolytic hydrogen production is highly dependent on the time-variant price and carbon footprint of electricity. In the present contribution, we analyse the economic feasibility of transitioning key carbon-intensive industries, steelmaking, and ammonia production, to green electrolytic hydrogen. Also, we investigate the competitiveness of green electrolytic hydrogen with other environmentally sustainable hydrogen sources derived from biomethane, biogas, and natural gas (associated with carbon capture and storage). We perform process design for steelmaking, ammonia production, and biogas-based steam reforming in order to determine key performance indicators such as costs, conversion factors, and GHG emissions. In particular, we allow for dynamic operation of the industrial processes... [more]

In this work, a conceptual design is presented of a HVO/green diesel production unit with a processing capacity of 74 ton/h (500 000 ton/year) of vegetable oils and a production rate of 59 ton/h of diesel. Firstly, an extensive literature review has been conducted regarding the state-of-the-art techniques as well as process equipment, mechanisms of reaction and thermodynamical properties. A market analysis is also presented which estimates feedstock availability and target production rate. With this information, a preliminary Process Flow Diagram is proposed, along with explanations on the type of equipment used and its operating conditions. Process design and simulation has been performed using Aspen Plus®, while Aspen Custom Modeler® has been used to develop more accurate models where necessary. The present study concludes with an analysis of process flexibility, considerations for heat integration and an economic assessment.

This work proposes a conceptual process design of a production plant for hydrotreated vegetable oil (HVO). Palm oil is selected to be the most promising feedstock in terms of costs and chemical composition. Since UNIFAC is unable to correctly estimate the behavior of the liquid phase, an implementation of COSMO-RS is used as a more appropriate tool for the parameter estimation. As pre-treatment inorganic impurities in palm oil are removed with citric acid. A sulfur-free-Ni-catalyst embedded into a trickle bed reactor is applied for the conversion of palm oil to paraffinic fuel. Unit production costs of HVO of 0.85USD/kg (U.S.) and 0.91USD/kg (EU-27) are determined by using current palm oil prices. Those results are found to be marginally higher than costs for biodiesel production from palm oil. The blending capabilities of HVO with various diesel surrogates are calculated considering the DIN EN 590 standard.

Algal biomass production, mineralization, and chemical conversion as promising carbon dioxide utilization processes are compared with regard to economic as well as environmental factors. The production of the chemicals methanol, dimethyl ether, and dimethyl carbonate is selected as the most viable alternative among all options. The integrated production of the proposed chemicals is evaluated for a wide range of trade-offs between economic potential and environmental impact by applying multi-objective superstructure optimization. The results indicate that direct hydrogenation of CO2 to methanol with subsequent dehydration to dimethyl ether is on the verge of profitability (including capture cost) while achieving a positive net CO2 consumption of ca. 68% of supplied CO2 when direct and indirect emissions are accounted for; and 85% when only direct emissions are considered.

In this work, we propose a process to reduce CO2 emissions through its capture and utilization (CCU) as a raw material for producing valuable products in the chemical industry. As a case study, we design and evaluate the economic and environmental performances of a direct dimethyl ether (DME) synthesis from syngas plant reusing CO2 as a raw material. The decision making is carried out including all the design variables into a flowsheet superstructure, which is simulated and optimized to maximize the process profit. The optimum production of DME is 219.95 kt/year at 99.95% purity, with a profit of $51.01 million/year and emitting 0.784 kg CO2-eq/kg DME produced. After heat integration implementation, the profit is raised to $58.68 million/year and emissions are reduced to 0.510 kg CO2-eq/kg DME, being the latter a 61.4% lower than the one associated to the classic DME production. The financial risk associated with the post heat integration process is at 15.4%, while considering a 5% ris... [more]

This is the source code written in MATLAB for the stochastic, agent-based model for naive CD8+ T cell recirculation dynamics in mice. The model simulates the migration of naive CD8+ T cells between the blood and major lymphoid tissues in the body for 47 hours post i.v. transfer. It is also capable of predicting the effect of an immunosuppressant drug FTY720 on blocking naive CD8+ T cell egress from lymph nodes.

Ethylene is a key platform chemical in global manufacturing, yet its conventional production via steam cracking is highly energy-intensive and a major source of industrial CO2 emissions. This study proposes a sustainable alternative for ethylene synthesis through the electrochemical reduction of captured CO2 via alkaline electrolysis powered by intermittent offshore wind energy. A selective catalytic pathway for the CO2 reduction reaction is identified and modeled in ASPEN PLUS®, with full integration of reaction, separation, and recycle units. To address the variability in renewable energy supply, a time-variable process optimization framework is developed in Pyomo, enabling operational flexibility through integrated process planning and scheduling. Three electricity sourcing scenarios are analyzed, each representing different balances between grid and renewable power. A gate-to-gate life cycle assessment reveals a significant greenhouse gas emission reduction, with the most renewable... [more]

Contains the Aspen Plus flowsheet files and Python source code for the modelling, simulation, and optimization of a process which converts captured CO2 and electricity into ethylene, considering intermittent electricity.

A technical evaluation on the production of sustainable formaldehyde was presented in this report, including process design, advanced simulation, economic analysis, and environmental analysis. Three process configurations to produce formaldehyde were developed: a base-case with no capture of carbon, a post-combustion capture (PCC) process, which utilized 14 wt.% MEA solution-based process, and a direct air capture (DAC) route which used NaOH. Sequestered CO₂ was used as a major feedstock for methanol production via an electrocatalytic reactor (ECR), after which was converted into formaldehyde via a FORMOX process. Large-scale simulations were carried out, demonstrating a yearly methanol production capacity of approximately 62 million kilograms, with a fixed formaldehyde-to-methanol conversion ratio of 1.4 kg per kg of methanol. Economic models were developed using Aspen Process Economic Analyser, indicating that the base-case option (without capture) would involve a capital expenditure... [more]

Aspen Plus simulations for the conversion of CO2 into Formaldehyde and related processes.

GAMS models and supporting spreadsheets for Innovative Strategies in Sustainable Formaldehyde Production in Belgium: Integrating Process Optimisation, Carbon Capture, and a comprehensive Environmental Assessment.