Browsing by Author "Nyári, Judit"
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- Awareness increases acceptance and willingness to pay for low-carbon fuels amongst marine passengers
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2024-02-15) Nyári, Judit; Toldy, Árpád I.; Järvinen, Mika; Santasalo-Aarnio, AnnukkaOne of the main applications discussed in decarbonising the marine sector is via alternative fuels, such as methanol and ammonia, produced from renewable hydrogen. These alternative, low-carbon fuels often come with increased prices and operational expenses for the vessel operators, which are ultimately reflected in the passengers' costs. Therefore, it is important to assess passengers' familiarity with expressions linked to decarbonisation and their willingness to pay this ‘green premium’ for alternative fuels. To assess these, we ran a survey-based study and collected close to 2000 answers through different channels from marine passengers, specifically from those travelling in the Northern European region on roll-on/roll-off passenger (RoPax) vessels. We found that most of the passengers prioritise environmental friendliness in marine fuels and are concerned about environmental issues. However, there seems to be a lack of knowledge about fuels and fuel technologies. Familiarity with certain alternative fuel-related expressions results in a more positive view of them. The observed willingness to pay is affected by the level of education, income, and place of residence, in addition to the level of concern about environmental issues, frequency of travel and spending on trips. Close to 80% of passengers are willing to increase their spending if the vessel is powered by a low-carbon, alternative fuel. As the results indicate that the more passengers know about alternative fuels and their benefits, the more willing they are to pay for them, it is recommended that RoPax operators invest in educating them. - Carbon Capture, Utilisation and Storage (CCUS)
Insinööritieteiden korkeakoulu | Bachelor's thesis(2020-05-03) Saarikoski, Aleksandra - Choice of the kinetic model significantly affects the outcome of techno-economic assessments of CO2-based methanol synthesis
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-11-01) Nyári, Judit; Izbassarov, Daulet; Toldy, Árpád I.; Vuorinen, Ville; Santasalo-Aarnio, AnnukkaCarbon dioxide hydrogenation to methanol is a cornerstone of the CO2 utilization toolkit, and its comparison to fossil-based methanol through techno-economic assessments (TEAs) has helped establish barriers to its commercial feasibility. TEAs are often performed in process simulation software that relies on kinetic models (KMs). The choice of KM could influence the outcome of the TEA, however, their effect has not been quantified earlier. This study quantifies this effect through TEAs performed using three different KMs in Aspen Plus™. Three KMs are selected for comparison: two of them are commonly used in TEAs while also a third, a recently published model, will be studied herein. The models are first validated in Aspen Plus™ and then compared in a series of sensitivity analyses in a one-pass reactor. Finally, a TEA study is conducted for a large-scale methanol plant to investigate the effects of the KM choice. It was found that the choice of the kinetic model significantly influences the results of TEAs as it can result in a 10% difference in the levelized cost of methanol. This can be mainly attributed to differences in one-pass yield. As CO2 utilization approaches economic viability, understanding such uncertainties will be crucial for successful project planning. Hence, these results suggest that extending a TEA's sensitivity analysis to cover the KM's contribution could increase confidence in the robustness of the TEA. - Methane cracking for clean hydrogen production
Insinööritieteiden korkeakoulu | Bachelor's thesis(2022-12-04) Alopaeus, Jan - Methanol production via carbon dioxide hydrogenation for the maritime sector - Techno-economic assessment and social acceptance
School of Engineering | Doctoral dissertation (article-based)(2023) Nyári, JuditInterest in Power-to-X technologies, where X stands for various chemical molecules produced from renewable electricity via water electrolysis, has recently accelerated. Methanol is one of these X molecules, where, in addition to hydrogen, captured carbon dioxide also participates in the synthesis. Methanol is an excellent alternative fuel for the maritime industry due to its high energy density, ease of storage and distribution thanks to its liquid state at ambient conditions, biodegradability, and water miscibility. This research has investigated the utilisation of synthetic methanol and the techno-economics of its production. The techno-economics part has focused on assessing large-scale synthetic methanol plants, while the utilisation part investigated methanol usage as an alternative marine fuel from the social acceptance point of view. Aspen Plus® was utilised for the process modelling environment in the techno-economic part. The developed plants ranged from industrial-scale comparable in output to fossil methanol plants to smaller but still large-scale plants. The energy efficiency of these plants was around 80%, and the differences can be attributed mainly to the varying targets of the heat integration. Furthermore, a new parameter was introduced to the process simulation environment, the implemented kinetic model describing methanol synthesis. The selected three kinetic models were first compared in a simple one-pass reactor and later in full-scale synthetic methanol plants. The most recent model has outperformed the other two in all technical key performance indicators. The most recent kinetic model also predicts the lowest levelised cost of methanol, which was 801 €/tonne, 10% below the worst-performing model. Overall, the levelised cost of methanol was calculated to be around 700-900 €/tonne, which is around 75% higher than the current fossil methanol price at 395 €/tonne. Moreover, a series of sensitivity analyses were also conducted, which found that synthetic methanol's production cost is significantly influenced by the cost of electricity and the potential co-sale of the oxygen by-product from the electrolyser. In this research, the developed one-pass reactor model in Aspen Plus® was also used to verify a mathematical model in computational fluid dynamics describing synthetic methanol synthesis and the process conditions' effect. In the utilisation part of this research, passengers of roll-on/roll-off passenger vessels were questioned about their knowledge and preferences of alternative marine fuels and other emission mitigation tools. The research found that most passengers are willing to accept increased fare prices when the vessel runs on alternative marine fuels. Furthermore, passengers prefer lower-emitting fuels and fuel production technologies; however, they lack the knowledge to decide consciously. - A numerical performance study of a fixed-bed reactor for methanol synthesis by CO2 hydrogenation
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-04-26) Izbassarov, Daulet; Nyári, Judit; Tekgül, Bulut; Laurila, Erkki; Kallio, Tanja; Santasalo-Aarnio, Annukka; Kaario, Ossi; Vuorinen, VilleSynthetic fuels are needed to replace their fossil counterparts for clean transport. Presently, their production is still inefficient and costly. To enhance the process of methanol production from CO2 and H2 and reduce its cost, a particle-resolved numerical simulation tool is presented. A global surface reaction model based on the Langmuir-Hinshelwood-Hougen-Watson kinetics is utilized. The approach is first validated against standard benchmark problems for non-reacting and reacting cases. Next, the method is applied to study the performance of methanol production in a 2D fixed-bed reactor under a range of parameters. It is found that methanol yield enhances with pressure, catalyst loading, reactant ratio, and packing density. The yield diminishes with temperature at adiabatic conditions, while it shows non-monotonic change for the studied isothermal cases. Overall, the staggered and the random catalyst configurations are found to outperform the in-line system. - Power-to-X: Modelling of Fischer-Tropsch synthesis in Aspen Plus
Sähkötekniikan korkeakoulu | Master's thesis(2022-01-24) Sayed Ahmed, HassanGlobal warming is the most challenging problem we are facing nowadays. Simultaneously, the energy sector is responsible for about three-quarters of the global greenhouse gas emissions. Electrification has been the main solution for defossilizing the energy sector in the last years, to tackle the emissions problem. In spite of that, many parts of the energy sector are hard to electrify, such as industry, aviation, marine, and heavy transport vehicles. Power-to-X (PtX) can contribute to tackling this problem. When using renewable electricity to produce hydrogen and capture carbon dioxide, different near carbon-neutral fuels can be produced via different PtX technologies, such as methanol, kerosene, diesel, gasoline, and natural gas. In this thesis, more focus will be given to producing diesel via Fischer-Tropsch (FT) synthesis. In this thesis, first, a summary of some PtX technologies is given, where their contribution in defossilizing the energy sector is investigated. Then, a techno-economic analysis of carbon-neutral FT synthesis is conducted, where Aspen Plus is used to model the process with having hydrogen and carbon dioxide as feedstock. Moreover, Carbon-neutral FT synthesis readiness for large-scale production is investigated, and the overall efficiency of carbon-neutral FT synthesis and the Levelized cost of FT fuels (LCOF) are calculated. It was found that PtX technologies can produce fuels that directly replace fossil ones with using the same infrastructure or with little modifications. Moreover, it can add more flexibility and reliability to the electricity sector, which enables more dependence on solar and wind energies. Besides, it was found that carbon-neutral FT synthesis is not yet ready for large scale production, mainly because of reverse water gas shift reaction which has TRL 6, and it was found that the overall efficiency of carbon-neutral FT synthesis is about 39%, so more work needs to be done to increase the efficiency of the process and its readiness for large scale production. On the other hand, FT fuels were found to be from 2.5 to 5 times more expensive than their equivalent fossil fuels. Hydrogen price was found to be the main contributor to this high cost, as it accounted for about 80% of the LCOF. If green hydrogen prices reached 0.5 €/kg, FT hydrocarbons will start to be economically competitive with their fossil equivalent hydrocarbons. Therefore, more efforts have to be given to reduce the cost of green hydrogen production to make FT fuels as economically competitive as possible with their fossil counterparts. - A Review of the Recast Renewable Energy Directive Provisions on Renewable Fuels Used in the Transport Sector
Insinööritieteiden korkeakoulu | Bachelor's thesis(2020-05-02) Irrmann, Lionel - Techno-economic barriers of an industrial-scale methanol CCU-plant
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-07) Nyári, Judit; Magdeldin, Mohamed; Larmi, Martti; Järvinen, Mika; Santasalo-Aarnio, AnnukkaGlobal anthropogenic CO2 emissions are expected to peak to 40Gt in 2020. If these emissions are not mitigated climate change and global warming will further aggregate. Meanwhile, demand for products and fuels produced from fossil raw materials are increasing. CO2, however, can be considered as feedstock for certain materials and processes. If CO2 is catalytically synthesised with H2 it can form a variety of hydrocarbons, such as methane, methanol (MeOH), higher alcohols, and liquid fuels. In this paper, a simulation model of a MeOH plant using CO2 and H2 as feedstock was developed in Aspen Plus™. This is the first plant studied at an industrial-scale comparable with fossil MeOH plant units. The plant produces 5kt chemical-grade MeOH daily that can be used as raw material for the chemical industry or as a fuel. The kinetic model, considering both CO and CO2 as the source of carbon, accomplished high overall CO2 conversion rate and close to stoichiometric raw material utilisation. Under the current market conditions, the MeOH plant is not feasible even at this scale. The most significant cost parameter making the plant non-viable is attributed to the high cost of H2 produced by water electrolysis. A series of sensitivity analyses revealed that co-selling of O2 by-product from the electrolyser and lowering the H2 cost price have a significant factor in achieving a more competitive levelised cost of MeOH. These economic results are analysed in-depth with previous studies to reveal the effect of different economic assumptions. - Techno-economic feasibility study of a methanol plant using carbon dioxide and hydrogen
Insinööritieteiden korkeakoulu | Master's thesis(2018-10-29) Nyári, JuditIn 2015, more than 80% of energy consumption was based on fossil resources. Growing population especially in developing countries fuel the trend in global energy consumption. This constant increase however leads to climate change caused by anthropogenic greenhouse gas (GHG) emissions. GHG, especially CO2 mitigation is one of the top priority challenges in the EU. Amongst the solutions to mitigate future emissions, carbon capture and utilization (CCU) is gaining interest. CO2 is a valuable, abundant and renewable carbon source that can be converted into fuels and chemicals. Methanol (MeOH) is one of the chemicals that can be produced from CO2. It is considered a basic compound in chemical industry as it can be utilised in a versatility of processes. These arguments make methanol and its production from CO2 a current, intriguing topic in climate change mitigation. In this master’s thesis first the applications, production, global demand and market price of methanol were investigated. In the second part of the thesis, a methanol plant producing chemical grade methanol was simulated in Aspen Plus. The studied plants have three different annual capacities: 10 kt/a, 50 kt/a and 250 kt/a. They were compared with the option of buying the CO2 or capturing it directly from flue gases through a carbon capture (CC) unit attached to the methanol plant. The kinetic model considering both CO and CO2 as sources of carbon for methanol formation was described thoroughly, and the main considerations and parameters were introduced for the simulation. The simulation successfully achieved chemical grade methanol production, with a high overall CO2 conversion rate and close to stoichiometric raw material utilization. Heat exchanger network was optimized in Aspen Energy Analyzer which achieved a total of 75% heat duty saving. The estimated levelised cost of methanol (LCOMeOH) ranges between 1130 and 630 €/t which is significantly higher than the current listed market price for fossil methanol at 419 €/t. This high LCOMeOH is mostly due to the high production cost of hydrogen, which corresponds to 72% of LCOMeOH. It was revealed that selling the oxygen by-product from water electrolysis had the most significant effect, reducing the LCOMeOH to 475 €/t. Cost of electricity also has a significant influence on the LCOMeOH, and for a 10 €/MWh change the LCOMeOH changed by 110 €/t. Finally, the estimated LCOMeOH was least sensitive for the change in cost of CO2. When comparing owning a CC plant with purchasing CO2, it was revealed that purchasing option is only beneficial for smaller plants. - A three-dimensional conjugate heat transfer model for methanol synthesis in a modular millireactor
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-08-31) Izbassarov, Daulet; Nyári, Judit; Laitinen, Alpo; Laari, Arto; Santasalo-Aarnio, Annukka; Vuorinen, VilleIn this work, a modular millireactor (MMR) is designed and modeled using the computational fluid dynamics (CFD) tool OpenFOAM. First, the method is validated against a conventional packed bed reactor (PBR) model (1D) with Aspen Plus. Next, the method is applied to study the effects of pressure (2–6 MPa) and temperature (483–533 K) on the performance of the MMR. Conjugate heat transfer (CHT) CFD results for the MMR are compared against a corresponding PBR at isothermal conditions. For the MMR, the methanol yield is shown to vary between 9–23 % within the studied parameter range. Overall, the MMR outperforms the PBR at conditions studied in this work. The maximum difference in methanol yield between MMR and the PBR is noted to be a factor of 1.71 at 533 K and 5 MPa. Such a large discrepancy advocates the usage of 3D CHT/CFD.