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The aviation sector needs to reduce its environmental impacts, like climate change and air pollution. New hybrid-electric aircraft concepts may contribute to abating part of these impacts. But to what extent and under which conditions? This study addresses these questions in the context of regional aviation and identifies technologies and concrete actions required for more environmentally sustainable aviation. The environmental impacts of emerging hybrid-electric aircraft configurations deployed in 2030, 2040, and 2050 have been comprehensively quantified using prospective life cycle assessment. The entire life cycle of the conventional and hybrid-electric aircraft configurations was encompassed, covering various technologies and systems like batteries, fuel cells, hydrogen, and selected alternative aviation fuel (AAF) systems. For these elements, detailed life cycle inventories stemming from primary data, literature, and prospective environmental databases were used, and uncertainty was evaluated. Results showed that hybrid-electric aircraft with Li-ion batteries appear as a promising transition technology in the short-term while aircraft propelled by fuel cells using hydrogen from electrolysis yield important environmental benefits relative to conventional aircraft in longer time horizons. In contrast, the studied AAFs present little or no environmental benefits when considering environmental impacts holistically, demonstrating the need to revise existing AAF frameworks and incentives globally. Environmental burden-shifting from flight emissions in conventional aircraft systems to airport operations and aircraft manufacturing in hybrid-electric aircraft is also observed in the results, thus calling for strengthened support to airports in their sustainability management and increased integration of ecodesign practices in future aircraft design and development.

This study investigates the effect of three key firm characteristics (diversification, size, and age) on road freight companies’ early adoption of alternative fuel vehicles (AFVs). While previous studies have identified the determinants of the adoption intention of AFVs, a gap in the literature is research into firm characteristics and the early adopters of AFVs. Because early adopters play an important role in the diffusion of innovation, it is imperative to fill this gap. Based on a survey of 156 Swedish road freight companies and logistic regression analyses, we report that firm size and diversification affect the early adoption of AFVs. In addition, the partial impact of the importance of driver comfort and payload capacity on early adoption of AFVs has been reported. Other factors, including purchase price, fuel cost, and truck refueling efficiency, were not found to discriminate early adopters of AFVs from those who had not yet adopted AFVs. These findings imply to policymakers that the current instruments in use in Sweden, including the greenhouse gas mandate and the relatively high taxation on diesel fuel, have led to the adoption of AFVs by larger road freight companies. For vehicle producers aiming to scale up the production and sales of AFV, the findings suggest the benefit of targeting diversified and larger road freight companies in the first place. © 2024 The Author(s)

This study investigates the effect of three key firm characteristics (diversification, size, and age) on road freight companies’ early adoption of alternative fuel vehicles (AFVs). While previous studies have identified the determinants of the adoption intention of AFVs, a gap in the literature is research into firm characteristics and the early adopters of AFVs. Because early adopters play an important role in the diffusion of innovation, it is imperative to fill this gap. Based on a survey of 156 Swedish road freight companies and logistic regression analyses, we report that firm size and diversification affect the early adoption of AFVs. In addition, the partial impact of the importance of driver comfort and payload capacity on early adoption of AFVs has been reported. Other factors, including purchase price, fuel cost, and truck refueling efficiency, were not found to discriminate early adopters of AFVs from those who had not yet adopted AFVs. These findings imply to policymakers that the current instruments in use in Sweden, including the greenhouse gas mandate and the relatively high taxation on diesel fuel, have led to the adoption of AFVs by larger road freight companies. For vehicle producers aiming to scale up the production and sales of AFV, the findings suggest the benefit of targeting diversified and larger road freight companies in the first place. © 2024 The Author(s)

This study investigates the effect of three key firm characteristics (diversification, size, and age) on road freight companies’ early adoption of alternative fuel vehicles (AFVs). While previous studies have identified the determinants of the adoption intention of AFVs, a gap in the literature is research into firm characteristics and the early adopters of AFVs. Because early adopters play an important role in the diffusion of innovation, it is imperative to fill this gap. Based on a survey of 156 Swedish road freight companies and logistic regression analyses, we report that firm size and diversification affect the early adoption of AFVs. In addition, the partial impact of the importance of driver comfort and payload capacity on early adoption of AFVs has been reported. Other factors, including purchase price, fuel cost, and truck refueling efficiency, were not found to discriminate early adopters of AFVs from those who had not yet adopted AFVs. These findings imply to policymakers that the current instruments in use in Sweden, including the greenhouse gas mandate and the relatively high taxation on diesel fuel, have led to the adoption of AFVs by larger road freight companies. For vehicle producers aiming to scale up the production and sales of AFV, the findings suggest the benefit of targeting diversified and larger road freight companies in the first place. © 2024 The Author(s)

This study investigates the effect of three key firm characteristics (diversification, size, and age) on road freight companies’ early adoption of alternative fuel vehicles (AFVs). While previous studies have identified the determinants of the adoption intention of AFVs, a gap in the literature is research into firm characteristics and the early adopters of AFVs. Because early adopters play an important role in the diffusion of innovation, it is imperative to fill this gap. Based on a survey of 156 Swedish road freight companies and logistic regression analyses, we report that firm size and diversification affect the early adoption of AFVs. In addition, the partial impact of the importance of driver comfort and payload capacity on early adoption of AFVs has been reported. Other factors, including purchase price, fuel cost, and truck refueling efficiency, were not found to discriminate early adopters of AFVs from those who had not yet adopted AFVs. These findings imply to policymakers that the current instruments in use in Sweden, including the greenhouse gas mandate and the relatively high taxation on diesel fuel, have led to the adoption of AFVs by larger road freight companies. For vehicle producers aiming to scale up the production and sales of AFV, the findings suggest the benefit of targeting diversified and larger road freight companies in the first place. © 2024 The Author(s)

Denna studie har kartlagt vilka drivmedel som användes av svenska handelsflottans fartyg från 2016 och hur stor andel som inte var petroleumbaserad. Fokus riktades mot Linnéuniversitetets sjöingenjörsprogram där en analys av kursplaners mål samt innehåll belyste om alternativa drivmedel fanns inkluderat i utbildningen. Respondenterna på sjöingenjörsprogrammet var delaktiga i en intervjustudie som klargjorde om framtidsutsikter för realisering av alternativa drivmedel var möjlig. Resultaten visade att det fanns tre alternativa drivmedel inom svenska sjöfarten, där inga kurser hade direkt koppling men genom ledord fanns tre kurser med relevans till alternativa drivmedel. Det fanns ett gemensamt mål inom respondenterna på Linnéuniversitetet om alternativa drivmedel men vägen till förverkligande var inte klarsynt., A few years ago, marine diesel and heavy fuel oil were the fuels that drove shipsforward. But with new legal requirements and climate goals, other potential fuelshave seen the light of day. These alternative fuels have resulted in an increase in thesystems you need knowledge of on board. The purpose of the study is to focus onhow the education to become a marine engineer keeps up with the rapidtechnological development that is taking place today.The study was carried out in several stages where document studies were compiledand became the basis for an interview study. The first document study resulted inwhat fuel the Swedish merchant fleet's newer ships use. In addition to marine dieseland heavy oil, alternative fuels such as liquid natural gas, methanol and batteryoperation are also used. These alternative fuels are used or can be used on about athird of the surveyed ships today.The second document study was done against the marine engineering program tosee if there was any connection to alternative fuels in the education's syllabuses. Nodirect connection was found, but by using key words for alternative fuels, threecourses were found with content that could be associated with the alternative fuels.The results of the document studies formed the basis for an interview study in whichpersonnel linked to the marine engineering education at the Linnaeus Universitywere interviewed. The result of the interview study was that all respondents agreedthat education is needed in the alternative fuels that have arrived. However, therespondents did not agree on what the training should look like, as there were manydifferent education proposals. Since there were also expressions from respondentsabout time, knowledge, and resource shortages, they need to reach an agreementwith a way forward to be able to secure the educational efforts towards a commongoal.

This report examines the possibilities of decarbonising operation & maintenance vessels for a prospective floating offshore wind power park at the Utsira Nord site in Norway, through self-sufficient energy carrier production utilizing power-to-X-solutions. Possible alternative fuels are identified as compressed hydrogen, batteries, liquid hydrogen, ammonia, methanol, and biofuels, out of which the former two are the subject for thorough investigation in this report. The effects of an in-park electric charging buoy are also investigated. A literature study is conducted and projected technical properties for production, storage, and drivetrain for the year 2030 are compiled. Nine cases comprising drive trains for two vessel types – crew transfer vessels (CTV) and service operation vessels (SOV) -, production, and storage are constructed (including three base cases). Past and future electricity costs in Norway are analysed. Net present costs, levelized cost of energy (LCOE) of hydrogen, and fuel cost per MWh vessel output are determined. The global warming potential on a life cycle basis for components and energy use are determined. For CTVs, hydrogen is viable for short transits and battery solutions are not viable, as vessel mass and volume capacities are too low. For SOVs, battery systems are viable when combined with a charging buoy, hydrogen systems are viable regardless but also benefits from implementation of a charging buoy. Hydrogen solutions are 2.9 to 4.0 times more costly than the base cases, and battery-electric solutions are 7.0 times more costly. Global warming potential is reduced to 0.17 to 0.05 of the base cases, with hydrogen solutions performing the best. The inclusion of a charging buoy has potential to be a cost effective GWP abatement method.

This thesis explores the choice of alternative fuels in Gotland from a quantitative and qualitative perspective, the complex factors that influence Gotland residents' decisions to adopt alternative motor fuels, in order to better understand how private transport on Gotland is transitioning from conventional energy fuels to sustainable energy systems. In addition, this paper explores the issue of consistency between actions and intentions to adapt and the factors that lead to inconsistency. The paper also seeks to provide meaningful insights for academics and administrators seeking to explore the opportunities and address the challenges of transitioning to sustainable energy options. in order to better understand how private transport on Gotland is transitioning from conventional energy fuels to a sustainable energy system. In this thesis, 57 people aged 18 years and older who live in Gotland for more than 6 months per year were surveyed. The survey and data collection were done in the form of a questionnaire. The data was analysed by means of visual graphs as well as thematic analysis. The results of the study show a positive intention towards sustainability among Gotland residents. However, individuals prefer petrol and diesel fuels for convenience.

Denna studie har kartlagt vilka drivmedel som användes av svenska handelsflottans fartyg från 2016 och hur stor andel som inte var petroleumbaserad. Fokus riktades mot Linnéuniversitetets sjöingenjörsprogram där en analys av kursplaners mål samt innehåll belyste om alternativa drivmedel fanns inkluderat i utbildningen. Respondenterna på sjöingenjörsprogrammet var delaktiga i en intervjustudie som klargjorde om framtidsutsikter för realisering av alternativa drivmedel var möjlig. Resultaten visade att det fanns tre alternativa drivmedel inom svenska sjöfarten, där inga kurser hade direkt koppling men genom ledord fanns tre kurser med relevans till alternativa drivmedel. Det fanns ett gemensamt mål inom respondenterna på Linnéuniversitetet om alternativa drivmedel men vägen till förverkligande var inte klarsynt., A few years ago, marine diesel and heavy fuel oil were the fuels that drove shipsforward. But with new legal requirements and climate goals, other potential fuelshave seen the light of day. These alternative fuels have resulted in an increase in thesystems you need knowledge of on board. The purpose of the study is to focus onhow the education to become a marine engineer keeps up with the rapidtechnological development that is taking place today.The study was carried out in several stages where document studies were compiledand became the basis for an interview study. The first document study resulted inwhat fuel the Swedish merchant fleet's newer ships use. In addition to marine dieseland heavy oil, alternative fuels such as liquid natural gas, methanol and batteryoperation are also used. These alternative fuels are used or can be used on about athird of the surveyed ships today.The second document study was done against the marine engineering program tosee if there was any connection to alternative fuels in the education's syllabuses. Nodirect connection was found, but by using key words for alternative fuels, threecourses were found with content that could be associated with the alternative fuels.The results of the document studies formed the basis for an interview study in whichpersonnel linked to the marine engineering education at the Linnaeus Universitywere interviewed. The result of the interview study was that all respondents agreedthat education is needed in the alternative fuels that have arrived. However, therespondents did not agree on what the training should look like, as there were manydifferent education proposals. Since there were also expressions from respondentsabout time, knowledge, and resource shortages, they need to reach an agreementwith a way forward to be able to secure the educational efforts towards a commongoal.

In order for the aviation industry to meet the targets of the Paris agreement and reach net-zero by 2050, significant amounts of greenhouse-gas emissions are to be reduced. However, as the industry is essentially dependent on conventional jet fuel, it becomes necessary for alternative technologies to develop and phase out fossil-based fuels. The thesis aims to provide valuable insights into the challenges and potentials of alternative technologies, which include sustainable aviation fuel (SAF), hydrogen, and electric-powered aviation. Additionally, the thesis investigated the Science-Based Targets initiative, and challenged the interim 1.5oC aviation pathway. The findings emphasize the crucial role of stakeholder cooperation in achieving net-zero emissions by 2050. Moreover, the thesis underscores the need for significant investments in alternative technologies, in order to enable growth and make the solutions increasingly attractive compared to conventional jet fuel. Collaboration and innovation are essential for attaining environmental targets while balancing economic growth. The thesis also highlights the urgency of policies and regulations to promote additional SAF production investments in order to vastly increase the supply. Furthermore, while the Science-Based Targets initiative (SBTi) is an effective means of securing airlines' commitment to the Paris Agreement, the thesis concludes that the SBTi 1.5oC interim pathway for airlines is overly optimistic. While the SBTi 1.5oC interim pathway’s SAF estimates for 2050 could be achieved, the thesis suggests around 2 to 4 times lower SAF supply for 2030 compared to the SBTi’s estimates. This further emphasizes the airlines' difficulties in following the 1.5oC pathway and the need for the industry to accelerate its transformation and make space for alternative solutions in order to meet the environmental targets., För att flygindustrin ska nå målen i Parisavtalet och uppnå netto-nollutsläpp år 2050 måste betydande mängder växthusgasutsläpp minskas. Eftersom branschen är i grunden beroende av konventionellt flygbränsle blir det nödvändigt att utveckla alternativa teknologier för att fasas ut fossilbaserade bränslen. Avhandlingens syfte är att ge värdefulla insikter i utmaningarna samt möjligheterna med alternativa teknologier, vilket inkluderar hållbart flygbränsle (SAF), väte och elektriskt driven flygning. Dessutom undersökte avhandlingen Science-Based Targets-initiativet och utmanade det interimistiska 1.5°C-målet för flygindustrin. Resultaten betonar den avgörande rollen som samarbetande intressenter spelar för att uppnå netto-nollutsläpp år 2050. Dessutom understryker avhandlingen behovet av betydande investeringar i alternativa teknologier för att möjliggöra tillväxt och göra lösningarna allt mer attraktiva jämfört med konventionellt flygbränsle. Samarbetet och innovationen är nödvändiga för att uppnå miljömålen samtidigt som ekonomisk tillväxt möjliggörs. Avhandlingen betonar också brådskan med att införa policys och regleringar för att främja ytterligare produktion av hållbart flygbränsle (SAF) för att drastiskt öka tillgången. Medan Science-Based Targets-initiativet (SBTi) är ett effektivt sätt att säkerställa flygbolagens åtagande att uppfylla Parisavtalet, drar avhandlingen slutsatsen att SBTi:s interimistiska 1.5°C-mål för flygindustrin är alltför optimistiskt. Medan SBTi:s SAF-estimat för 2050 skulle kunna uppnås, föreslår avhandlingen en SAF-tillgång som är ungefär 2-4 gånger lägre för 2030 jämfört med SBTi:suppskattningar. Detta understryker ytterligare svårigheterna för flygbolag att hålla sig till 1.5oC målet samt nödvändigheten för flygindustrin att accelerera omställningen och skapa utrymme för alternativa lösningar för att uppnå miljömålen.

In order for the aviation industry to meet the targets of the Paris agreement and reach net-zero by 2050, significant amounts of greenhouse-gas emissions are to be reduced. However, as the industry is essentially dependent on conventional jet fuel, it becomes necessary for alternative technologies to develop and phase out fossil-based fuels. The thesis aims to provide valuable insights into the challenges and potentials of alternative technologies, which include sustainable aviation fuel (SAF), hydrogen, and electric-powered aviation. Additionally, the thesis investigated the Science-Based Targets initiative, and challenged the interim 1.5oC aviation pathway. The findings emphasize the crucial role of stakeholder cooperation in achieving net-zero emissions by 2050. Moreover, the thesis underscores the need for significant investments in alternative technologies, in order to enable growth and make the solutions increasingly attractive compared to conventional jet fuel. Collaboration and innovation are essential for attaining environmental targets while balancing economic growth. The thesis also highlights the urgency of policies and regulations to promote additional SAF production investments in order to vastly increase the supply. Furthermore, while the Science-Based Targets initiative (SBTi) is an effective means of securing airlines' commitment to the Paris Agreement, the thesis concludes that the SBTi 1.5oC interim pathway for airlines is overly optimistic. While the SBTi 1.5oC interim pathway’s SAF estimates for 2050 could be achieved, the thesis suggests around 2 to 4 times lower SAF supply for 2030 compared to the SBTi’s estimates. This further emphasizes the airlines' difficulties in following the 1.5oC pathway and the need for the industry to accelerate its transformation and make space for alternative solutions in order to meet the environmental targets., För att flygindustrin ska nå målen i Parisavtalet och uppnå netto-nollutsläpp år 2050 måste betydande mängder växthusgasutsläpp minskas. Eftersom branschen är i grunden beroende av konventionellt flygbränsle blir det nödvändigt att utveckla alternativa teknologier för att fasas ut fossilbaserade bränslen. Avhandlingens syfte är att ge värdefulla insikter i utmaningarna samt möjligheterna med alternativa teknologier, vilket inkluderar hållbart flygbränsle (SAF), väte och elektriskt driven flygning. Dessutom undersökte avhandlingen Science-Based Targets-initiativet och utmanade det interimistiska 1.5°C-målet för flygindustrin. Resultaten betonar den avgörande rollen som samarbetande intressenter spelar för att uppnå netto-nollutsläpp år 2050. Dessutom understryker avhandlingen behovet av betydande investeringar i alternativa teknologier för att möjliggöra tillväxt och göra lösningarna allt mer attraktiva jämfört med konventionellt flygbränsle. Samarbetet och innovationen är nödvändiga för att uppnå miljömålen samtidigt som ekonomisk tillväxt möjliggörs. Avhandlingen betonar också brådskan med att införa policys och regleringar för att främja ytterligare produktion av hållbart flygbränsle (SAF) för att drastiskt öka tillgången. Medan Science-Based Targets-initiativet (SBTi) är ett effektivt sätt att säkerställa flygbolagens åtagande att uppfylla Parisavtalet, drar avhandlingen slutsatsen att SBTi:s interimistiska 1.5°C-mål för flygindustrin är alltför optimistiskt. Medan SBTi:s SAF-estimat för 2050 skulle kunna uppnås, föreslår avhandlingen en SAF-tillgång som är ungefär 2-4 gånger lägre för 2030 jämfört med SBTi:suppskattningar. Detta understryker ytterligare svårigheterna för flygbolag att hålla sig till 1.5oC målet samt nödvändigheten för flygindustrin att accelerera omställningen och skapa utrymme för alternativa lösningar för att uppnå miljömålen.

It is essential to use alternative fuels if we are to reach the emission reduction targets set by the IMO. Hydrogen carriers are classified as zero-emission, while having a higher energy density (including packing factor) than pure hydrogen. They are often considered as safe alternative fuels. The exact definition of what safety entails is often lacking, both for hydrogen carriers as well as for ship safety. The aim of this study is to review the safety of hydrogen carriers from two perspectives, investigating potential connections between the chemical and maritime approaches to safety. This enables a reasoned consideration between safety aspects and other design drivers in ship design and operation. The hydrogen carriers AB, NaBH4, KBH4 and two LOHCs (NEC and DBT) are taken into consideration, together with a couple reference fuels (ammonia, methanol and MDO). After the evaluation of chemical properties related to safety and the scope of the current IMO safety framework, it can be concluded that safety remains a vague and non-explicit concept from both perspectives. Therefore, further research is required to prove the safe application of hydrogen carriers onboard ships., Ship Design, Production and Operations

Green hydrogen combined with PEM fuel cell systems is a viable option to meet the demand for alternative maritime fuels. However, hydrogen storage faces challenges, including low volumetric density, fire and explosion risks and transport challenges. We assessed over fifteen hydrogen carriers based on their maritime performance characteristics to determine their suitability for shipboard use. Evaluation criteria included energy density, locally zero-emission, circularity of process, safety, dehydrogenation process, logistic availability and handling. Thus, excluding ammonia and methanol because of these constraints, we found that borohydrides, liquid organic hydrogen carriers and ammoniaborane are the most promising hydrogen carriers to use on ships with PEM fuel cells. Borohydrides, specifically sodium borohydride, have high energy densities but face regeneration issues. The liquid organic hydrogen carrier dibenzyltoluene has a lower energy density but exhibits easy hydrogenation and good handling. Given varying operational demands, we developed a framework to assess the suitability of hydrogen carriers for use in different ship categories. Evaluating the three types of hydrogen carriers, using our framework and considering current practices, shows that these are viable options for almost all ship types. Thus, we have identified three types of hydrogen carriers, which should be the focus of future research., Ship Design, Production and Operations, Complex Fluid Processing

Biomasa biljaka je najveći obnovljivi izvor energije. Republika Srpska i Republika Srbija spadaju u vrh evropskih zemalja po količini raspoložive a neiskorišćene biomase. Biogas je proizvod koji se dobija anaerobnom razgradnjom organske supstance uz pomoć kompleksa mikroorganizama u biogasnim elektranama. Za dobijanje biogasa mogu poslužiti svi tipovi biomase, koja sadrži ugljene hidrate, proteine, masti, celulozu i hemicelulozu. U teoretskom smislu, biogas se može proizvesti iz bilo kog supstrata organskog porijekla. Takođe, postoje mogućnosti da se razne vrste supstrata kombinuju u jednom biogas postrojenju., Plant biomass is the largest renewable energy source. Republic of Srpska and the Republic of Serbia are among the top European countries in terms of the amount of available and unused biomass. Biogas is a product obtained by anaerobic decomposition of organic matter with the help of a complex of microorganisms in biogas power plants. All types of biomass which contains carbohydrates, proteins, fats, cellulose and hemicellulose can be used to obtain biogas. In theoretical terms, biogas can be produced from any substrate of organic origin. Also, there are possibilities to combine different types of substrates in one biogas plant.

This paper explores the design and feasibility of a 200-passenger, 30- to 40-knot emission-free ferry as a potential variant of the traditionally powered Coastal Cruiser 200 ferry currently operating in the Chinese Pearl River Delta. The Pearl River Delta is one of China’s most densely urbanized regions and faces numerous social, health, and economic issues due to air pollution. In addition, globally, there are no currently-operating zero-emission ferries that, at minimum, sail at 30 knots and carry 200 passengers. To assess the feasibility of the new ferry, a two step approach was followed. First, an evaluation of efficiency improving measures, energy carriers, and propulsion systems was performed to assess the tradeoffs and identify early design choices. Second, to quantify the most technically feasible design, a technical parametric model was developed specifically for this case study. Results showed that the ferry is technically feasible using batteries, compressed hydrogen fuel cells, or liquid hydrogen fuel cells; however, each has its distinct advantages and disadvantages which influence the potential final viability. Despite the regional focus of the case study, results are applicable to all ferries with similar design requirements., Ship Design, Production and Operations

Climate change due to greenhouse gas emissions is prompting the IMO to reduce emissions by 80% by 2050. This thesis focuses on designing modular propulsion systems for mid-speed sailing vessels to meet these regulations. It designs a framework to generate and swiftly evaluate propulsion system designs on the basis of five performance indicators: Weight, Volume, Life Cycle Costing, Modularity and Emissions. Additionally, the framework is proven on the basis of a case study, which results in a modular concept., Marine Technology | Marine Engineering

This study observes the characteristics of the flame of biogas combustion in micro/meso-scale (MSC) combustion technology, namely in a cylindrical MSC with fuel variations and combustor variations with backward-facing step size (bfs) as the flame holder in the combustor as a comparison. The bfs are varied by changing the combustor's length of the inlet diameter. In contrast, the size of the outlet diameter of the combustor is always constant to obtain a continuous combustion reaction zone. Biogas, butane gas (C4H10), and a mixture of biogas-butane are used as fuel, with air as the oxidizing agent. The results showed that the type of fuel, reactant flow velocity, and equivalent ratio that occurred in the fuel variation and the bfs variation of the cylindrical MSC influenced the flame characterization. Stable flame forms in the stoichiometric to rich equal ratio area and medium to high reactant velocity area. The best characterization of biogas combustion is formed in the variation of biogas treatment by mixing butane gas (biogas-butane). One of the methods used is called with a wider flame stability limit area, more varied flame visualization variations with a more widely distributed flame mode map, and flame and combustor wall temperature higher than the characterization of biogas combustion without mixing butane gas for the possible test ranges.

Ship designers face increasing pressure to comply with global emission reduction ambitions. Alternative fuels, potentially derived from bio-feedstock or renewable electricity, provide promising solutions to this problem. The main challenge is to identify a suitable ship power system, given not only uncertain emission requirements but also uncertain fuel and carbon emission prices. We develop a two-stage stochastic optimization model that explicitly considers uncertain fuel and carbon emission prices, as well as potential retrofits along the lifetime. The bi-objective setup of the model shows how the choice of optimal power system changes with reduced emission levels. Methanol and LNG configurations appear to be relatively robust initial choices due to their ability to run on fuel derived from different feedstocks, and their better retrofittability towards ammonia or hydrogen. From a policy perspective, our model provides insight into the effect of the different types of carbon pricing mechanisms on a shipowner's decisions.

In this work, the low-temperature pyrolysis of a real plastic mixture sample collected at a WEEE-authorised recycling facility has been investigated. The sample was pyrolysed in a batch reactor in different temperature and residence time conditions and auto-generated pressure by following a factorial design, with the objective of maximising the liquid (oil) fraction. Furthermore, the main polymers constituting the real sample were also pyrolysed in order to understand their role in the generation of oil. The pyrolysis oils were characterised and compared with commercial fuel oil number 6. The results showed that in comparison to commercial fuel oil, pyrolysis oils coming from WEEE plastic waste had similar heating values, were lighter and less viscous and presented similar toxicity profiles in fumes of combustion.

International and local legislation on emission reduction urge the Dutch beam trawler fleet to reduce the use of fossil fuels. In 2015 the United Nations Paris Agreement was signed and as a result IMO and EU set the objective to reduce the GHG or CO2 emissions of the shipping industry. The Dutch beam trawler has been confronted with many developments within the last decade that reduced the profitability. Two developments that stand out are: (1) Brexit: the Brexit resulted in a significant reduction in available fishing grounds, (2) Ban on pulse fishing: this method of fishing reduced the operational expenses with 30% to 40%, but is banned by the EU. Al a result to these developments in combination with upcoming (inter)national legislation, the Dutch government introduced a plan ”Noordzee visie” to help vessel owners to reduce their environmental impact. To continue fishing a Dutch beam trawler therefor has to take measurements to comply with these regulations. It will be inevitable to implement the use of sustainable fuels together with energy saving technologies. Vessel owners want to implement these, but without sacrificing operational effectiveness. Therefor it is required to find how different propulsion configuration which are able to reduce CO2 will influence the technical and economical performance of a Dutch trawler. This research consists of two parts: (1) Literature study and (2) Result processing. Within the literature study the current state of a Dutch beam trawler is defined. Secondly potential converters, energy carriers and energy reduction methods are identified which show potential. At last an assessment model is build to find the influence of available propulsion configurations. The technical feasibility is determined by the configuration being able to comply with: operational effectiveness requirements, maximum added draught, maximum added length, and being able to reduce the CO2 emission with at least 40%. The economical performa, Marine Technology

The maritime sector is actively investigating new solutions for zero emissions in response to climate change. One of the promising options is hydrogen-based propulsion, but there are currently no prescriptive rules or legislation to approve the design of such innovative, unproven technology. The International Maritime Organization (IMO) requires a quantitative risk assessment to demonstrate that the safety level of hydrogen-fueled vessels is equivalent to that of conventional-fueled vessels. To address this challenge, a risk-based design approach is needed, and the quantitative risk assessment process plays a crucial role in the early design stage. This research contributes to the technical understanding and potential of zero-emission maritime hydrogen propulsion solutions, by designing a quantitative risk assessment system for analyzing and evaluating risks associated with this innovative technology. The developed risk-analysis system could be a useful tool for future development. While compressed hydrogen design has matured and undergone relevant risk studies, its low volumetric energy density limits its sailing distance. Liquid hydrogen provides a more energy-dense solution, enabling longer-distance sea-going missions, but its application in the maritime industry lacks related risk studies. Therefore, this study aims to design a quantitative risk assessment system for maritime liquid hydrogen propulsion that can analyze and evaluate risks adequately. The methodology of this study includes a conceptual design of a liquid hydrogen-fueled vessel, followed by hazard identification and scenario selection. The Bayesian theory was used to assess the leak frequencies of components operating with liquid and gaseous hydrogen from published literature, with adjustments made for the harsh maritime environment and mechanical systems. Ignition probability models were proposed, and validated consequence models were used to simulate hazards. Risks are prese, Marine Technology | Marine Engineering

This paper investigates the spatial requirements of alternative marine energy carriers and their impact on ship design and powering for constant operational requirements. A parametric design tool for bulk carriers, tankers, and container ships has been developed for the predicted future marine energy carriers to determine the main engine brake power increase. The results indicate that all ship type and energy carrier combinations require a higher total installed engine power and consequently a higher energy carrier consumption. The results are intended to support the determination on the total environmental impact of marine energy carriers while taking the increased energy consumption into account., http://resolver.tudelft.nl/uuid:cc64addb-aeb4-42ca-b4a8-746151306174 link to graduation project 'Alternative marine energy carrier impact on ship powering and the environment', Marine Technology | Maritime Operations and Management, Marine Technology | Ship Design

PIANC provides guidance and technical advice for sustainable waterborne transport infrastructure. To address the challenge of making inland navigation infrastructure sustainable, a Task Group “Infrastructure for the decarbonisation of Inland Water Transport” (TG234) was set up in January2021. The objective of the TG was to identify knowledge gaps and major challenges that need to be urgently addressed and advise PIANC on further actions, such as setting up a working group. A report was to be delivered in early2022. The TG involved a range of international experts who met every three months on-line. They jointly participated in the following activities: sharing experiences in their area of expertise; gathering, organising, and discussing literature; discussing the perspective to be taken while reporting; contributing an overview of the developments either in their country or organisations and of course in the various discussions. A final report was produced that took the perspective of the waterway manager, highlighting a number of key questions that need to be answered in the transition to reduced/zero emissions. With the state-of-art knowledge gathered by the group, it became possible to identify the existing knowledge gaps and the major challenges that need to be addressed. The report can guide PIANC in evaluating the best way forward to address the decarbonisation of IWT infrastructure., Rivers, Ports, Waterways and Dredging Engineering

Many fuels are currently considered for reducing the emissions in shipping; Methanol, LNG, Ammonia, Nuclear, Biodiesel, etc. However, Bio-ethanol is not considered at all.This research looked into all aspects of ethanol in a comparison with its most closely related alternative methanol. Using a similar approach as found in earlier comparisons. Though updating the data as well as the application ot vessels relevant for the Dutch ship owners. This research identified that 2nd generation bio-ethanol would in price be close to 2nd generation bio-methanol, but with several technical advantages. Furthermore the bio-ethanol production capacity is far larger than that of any of the other alternative fuels for shipping and with the ongoing electrification of cars, this capacity will most likely be looking for a new market in the future, putting pressure on the price. Hence the report calls for further investigations and reconsiderations of bio-ethanol as a marine fuel., Ship Design, Production and Operations

An increasing demand in the marine industry to reduce emissions led to investigations into more efficient power conversion using fuels with sustainable production pathways. Solid Oxide Fuel Cells (SOFCs) are under consideration for long-range shipping, because of its high efficiency, low pollutant emissions, and fuel flexibility. SOFC systems also have great potential to cater for the heat demand in ships, but the heat integration is not often considered when assessing its feasibility. This study evaluates the electrical and heat efficiency of a 100 kW SOFC system for marine applications fuelled with methane, methanol, diesel, ammonia, or hydrogen. In addition, cathode off-gas recirculation (COGR) is investigated to tackle low oxygen utilisation and thus improve heat regeneration. The software Cycle Tempo is used to simulate the power plant, which uses a 1D model for the SOFCs. At nominal conditions, the highest net electrical efficiency (LHV) was found for methane (58.1%), followed by diesel (57.6%), and ammonia (55.1%). The highest heat efficiency was found for ammonia (27.4%), followed by hydrogen (25.6%). COGR resulted in similar electrical efficiencies, but increased the heat efficiency by 11.9% to 105.0% for the different fuels. The model was verified with a sensitivity analysis and validated by comparison with similar studies. It is concluded that COGR is a promising method to increase the heat efficiency of marine SOFC systems., Ship Design, Production and Operations

Using vehicles and other mobile systems to transport passengers and goods, approximately 25% of Europe's greenhouse gases are generated. At the same time, many research papers, published by researchers and students, promote the use of electric vehicles as zero-emission vehicles. Given that, more broadly, the emission of electric vehicles is higher, especially in countries where electricity is obtained by burning coal, the use of internal-combustion engines is still dominant. There are other reasons for using an internal-combustion engine, such as already developed pumping station infrastructure, which is not the case when recharging electric vehicles. Improvements in engine design contribute to meet the regulations relating to the fuel consumption and toxic gas emissions. This refers to the use of alternative fuels, improving the combustion process, and increasing efficiency (efficiency coefficient) by reducing losses. The research is focused on the problem of friction and wear in internal combustion engines and reciprocating air compressors, as auxiliary devices on engines. For that purpose, construction of the reciprocating air compressor in motor vehicles was redesigned. The paper presents the characteristic test results of material used to strengthen liner of the aluminum cylinder. Specifically, a method for testing the performance characteristics of a single-cylinder reciprocating compressor inside of an experimental installation for compressed air supply has also been proposed.

This thesis investigates the total environmental impact of various alternative marine energy carriers while taking the powering increase into account due to their disadvantageous spatial requirements compared to conventional fuel. A parametric design tool for bulk carriers, tankers, container ships, and trailing suction hopper dredgers has been developed for the future marine energy carriers to determine the total installed engine power increase. A more environmentally friendly energy carrier can be overturned because the total installed engine power increase is proportionate to the energy consumption increase. A comparative life cycle assessment (LCA) has been performed on fuel oil, methanol, LNG, liquid hydrogen, ammonia, and batteries for the conventional and a bio/renewable version of their well-to-wake pathway. The powering impact results indicate that all ship type and energy carrier combinations require a higher total installed main engine power and consequently a higher energy carrier consumption. The total environmental impact results indicate that only renewable liquid hydrogen and renewable ammonia have less adverse effects on global warming, and cause less damage to human health, ecosystems, and natural resource availability., Marine Technology | Maritime Operations and Management, Marine Technology | Ship Design

[ES] Las emisiones de CO2 en el sector transporte se han incrementado considerablemente durante los últimos años debido al desarrollo económico mundial. El crecimiento de las flotas de transporte, junto con otros factores, ha contribuido al desequilibrio del ciclo de carbono del planeta. Es por ello que el CO2 se considera un gas de efecto invernadero de origen antropogénico que debe ser reducido para evitar el calentamiento global. Las estrategias para reducir el CO2 en el sector transporte están enfocadas a la electrificación y al uso de combustibles neutros o de bajo impacto al ambiente. Sin embargo, una efectiva implementación de esta última requiere un profundo entendimiento de la combustión con tales combustibles. En la presente tesis doctoral, se ha caracterizado experimentalmente la combustión de diferentes tipos de combustibles, entre ellos, algunos de bajo impacto en emisiones de CO2 como lo son el Aceite Vegetal Hidrotratado (HVO) y dos éteres de oximetileno (OME1 y OMEx).Además, por su potencial en la reducción de contaminantes se han evaluado mezclas de diésel y gasolina y de HVO y Gas Licuado de Petróleo (LPG), lo que requirió adecuar el sistema de inyección para evitar la evaporación a lo largo de la línea. Todos estos combustibles y mezclas han sido inyectados con una tobera mono-orificio y han sido evaluados mediante técnicas de visualización a alta velocidad bajo diferentes condiciones termodinámicas típicas de un motor de encendido por compresión operando en condiciones de combustión a baja temperatura, en instalaciones con accesos ópticos. Se ha analizado el efecto de las propiedades físico químicas de estos combustibles y mezclas sobre los parámetros característicos de un chorro como lo son la longitud líquida y la penetración de vapor. La combustión ha sido evaluada mediante la caracterización del tiempo de retraso, de la liberación de calor y la longitud del despegue de la llama, que viene condicionada por el proceso de mezcla. Igualmente, el, [CA] Les emissions de CO2 en el sector transport s'han incrementat considerablement durant els últims anys a causa del desenvolupament econòmic mundial. El creixement de les flotes de transport, juntament amb altres factors, ha contribuït al desequilibri del cicle de carboni del planeta. És per això, que el CO2 es considera un gas d'efecte hivernacle d'origen antropogènic que ha de ser reduït per evitar l'escalfament global. Les estratègies per reduir el CO2 dins el sector transport, estan enfocades a l'electrificació i a l'ús de combustibles neutres o de baix impacte ambiental. No obstant això, una efectiva implementació d'aquesta última, requereix un profund coneixement del procés de combustió d'aquests combustibles. En la present tesi doctoral, s'ha caracteritzat experimentalment la combustió de diferents tipus de combustibles, entre ells, alguns de baix impacte en emissions de CO2 com són l'Oli Vegetal Hidrotratat (HVO) i dos èters de oximetileno (OME1 i OMEx) .A més , degut al seu alt potencial en la reducció de contaminants, s'han avaluat mescles de dièsel i gasolina, i de HVO i Gas Liquat de Petroli (LPG), el que va requerir adequar el sistema d'injecció per evitar l'evaporació al llarg de la línia. Tots aquests combustibles i mescles han estat injectats amb una tovera mono-orifici i han estat avaluats mitjançant tècniques de visualització a alta velocitat a través dels accessos òptics del que disposa la instal·lació. Les diferents condicions termodinàmiques utilitzades son típiques d'un motor d'encesa per compressió operant en condicions de combustió a baixa temperatura. S'ha analitzat l'efecte de les propietats fisicoquímiques d'aquests combustibles i de les mescles sobre els paràmetres característics d'un raig com són la longitud líquida i la penetració de vapor. La combustió ha estat avaluada mitjançant la caracterització del temps de retard, de l'alliberació de calor i de la longitud de l'enlairament de la flama que ve condicionada pel procés de mescla., [EN] CO2 emissions in the transport sector have increased considerably in recent years due to global economic development. The growth of transport fleets, along with other factors, has contributed to the imbalance of the planet's carbon cycle. For that, CO2 is considered a greenhouse gas from anthropogenic origin that must be reduced to avoid global warming. Strategies to reduce CO2 in the transport sector are focused on electrification and the use of neutral fuels or those with a low impact on the environment. However, an effective implementation of the latter requires a deep understanding of the combustion with those fuels. In this doctoral thesis, the combustion of different types of fuels has been experimentally characterized, including some with low impact on CO2 emissions such as Hydrotreated Vegetable Oil (HVO) and two oxymethylene ethers (OME1 and OMEx). Furthermore, due to their potential in reducing pollutants, blends of diesel and gasoline and HVO and Liquefied Petroleum Gas (LPG) have also been evaluated, which required adapting the injection system to avoid evaporation along the injection line. All these fuels and blends have been injected with a single-hole nozzle and they have been evaluated using high speed visualization techniques under different thermodynamic conditions typical of a compression ignition engine operating under low-temperature combustion conditions in installations with optical accesses. The effect of the physical-chemical properties of these fuels and blends on the characteristic parameters of a jet, such as the liquid length and the vapor penetration, has been analyzed. Combustion has been evaluated by characterizing the ignition delay, the heat release and the flame Lift-off length that is conditioned by the mixing process. Furthermore, the study of soot formation based on the fuel properties and the characteristics of the mixing process represents an important contribution of this thesis, showing that in addition to the benefits

[ES] Las emisiones de CO2 en el sector transporte se han incrementado considerablemente durante los últimos años debido al desarrollo económico mundial. El crecimiento de las flotas de transporte, junto con otros factores, ha contribuido al desequilibrio del ciclo de carbono del planeta. Es por ello que el CO2 se considera un gas de efecto invernadero de origen antropogénico que debe ser reducido para evitar el calentamiento global. Las estrategias para reducir el CO2 en el sector transporte están enfocadas a la electrificación y al uso de combustibles neutros o de bajo impacto al ambiente. Sin embargo, una efectiva implementación de esta última requiere un profundo entendimiento de la combustión con tales combustibles. En la presente tesis doctoral, se ha caracterizado experimentalmente la combustión de diferentes tipos de combustibles, entre ellos, algunos de bajo impacto en emisiones de CO2 como lo son el Aceite Vegetal Hidrotratado (HVO) y dos éteres de oximetileno (OME1 y OMEx).Además, por su potencial en la reducción de contaminantes se han evaluado mezclas de diésel y gasolina y de HVO y Gas Licuado de Petróleo (LPG), lo que requirió adecuar el sistema de inyección para evitar la evaporación a lo largo de la línea. Todos estos combustibles y mezclas han sido inyectados con una tobera mono-orificio y han sido evaluados mediante técnicas de visualización a alta velocidad bajo diferentes condiciones termodinámicas típicas de un motor de encendido por compresión operando en condiciones de combustión a baja temperatura, en instalaciones con accesos ópticos. Se ha analizado el efecto de las propiedades físico químicas de estos combustibles y mezclas sobre los parámetros característicos de un chorro como lo son la longitud líquida y la penetración de vapor. La combustión ha sido evaluada mediante la caracterización del tiempo de retraso, de la liberación de calor y la longitud del despegue de la llama, que viene condicionada por el proceso de mezcla. Igualmente, el, [CA] Les emissions de CO2 en el sector transport s'han incrementat considerablement durant els últims anys a causa del desenvolupament econòmic mundial. El creixement de les flotes de transport, juntament amb altres factors, ha contribuït al desequilibri del cicle de carboni del planeta. És per això, que el CO2 es considera un gas d'efecte hivernacle d'origen antropogènic que ha de ser reduït per evitar l'escalfament global. Les estratègies per reduir el CO2 dins el sector transport, estan enfocades a l'electrificació i a l'ús de combustibles neutres o de baix impacte ambiental. No obstant això, una efectiva implementació d'aquesta última, requereix un profund coneixement del procés de combustió d'aquests combustibles. En la present tesi doctoral, s'ha caracteritzat experimentalment la combustió de diferents tipus de combustibles, entre ells, alguns de baix impacte en emissions de CO2 com són l'Oli Vegetal Hidrotratat (HVO) i dos èters de oximetileno (OME1 i OMEx) .A més , degut al seu alt potencial en la reducció de contaminants, s'han avaluat mescles de dièsel i gasolina, i de HVO i Gas Liquat de Petroli (LPG), el que va requerir adequar el sistema d'injecció per evitar l'evaporació al llarg de la línia. Tots aquests combustibles i mescles han estat injectats amb una tovera mono-orifici i han estat avaluats mitjançant tècniques de visualització a alta velocitat a través dels accessos òptics del que disposa la instal·lació. Les diferents condicions termodinàmiques utilitzades son típiques d'un motor d'encesa per compressió operant en condicions de combustió a baixa temperatura. S'ha analitzat l'efecte de les propietats fisicoquímiques d'aquests combustibles i de les mescles sobre els paràmetres característics d'un raig com són la longitud líquida i la penetració de vapor. La combustió ha estat avaluada mitjançant la caracterització del temps de retard, de l'alliberació de calor i de la longitud de l'enlairament de la flama que ve condicionada pel procés de mescla., [EN] CO2 emissions in the transport sector have increased considerably in recent years due to global economic development. The growth of transport fleets, along with other factors, has contributed to the imbalance of the planet's carbon cycle. For that, CO2 is considered a greenhouse gas from anthropogenic origin that must be reduced to avoid global warming. Strategies to reduce CO2 in the transport sector are focused on electrification and the use of neutral fuels or those with a low impact on the environment. However, an effective implementation of the latter requires a deep understanding of the combustion with those fuels. In this doctoral thesis, the combustion of different types of fuels has been experimentally characterized, including some with low impact on CO2 emissions such as Hydrotreated Vegetable Oil (HVO) and two oxymethylene ethers (OME1 and OMEx). Furthermore, due to their potential in reducing pollutants, blends of diesel and gasoline and HVO and Liquefied Petroleum Gas (LPG) have also been evaluated, which required adapting the injection system to avoid evaporation along the injection line. All these fuels and blends have been injected with a single-hole nozzle and they have been evaluated using high speed visualization techniques under different thermodynamic conditions typical of a compression ignition engine operating under low-temperature combustion conditions in installations with optical accesses. The effect of the physical-chemical properties of these fuels and blends on the characteristic parameters of a jet, such as the liquid length and the vapor penetration, has been analyzed. Combustion has been evaluated by characterizing the ignition delay, the heat release and the flame Lift-off length that is conditioned by the mixing process. Furthermore, the study of soot formation based on the fuel properties and the characteristics of the mixing process represents an important contribution of this thesis, showing that in addition to the benefits

The aim of this paper is for the production of oils processed in refineries to come from the pyrolysis of real waste from the high plastic content rejected by the recycling industry of the Basque Country (Spain). Concretely, the rejected waste streams were collected from (1) a light packaging waste sorting plant, (2) the paper recycling industry, and (3) a waste treatment plant of electrical and electronic equipment (WEEE). The influence of pre-treatments (mechanical separation operations) and temperature on the yield and quality of the liquid fraction were evaluated. In order to study the pre-treatment effect, the samples were pyrolyzed at 460 °C for 1 h. As pre-treatments concentrate on the suitable fraction for pyrolysis and reduce the undesirable materials (metals, PVC, PET, inorganics, cellulosic materials), they improve the yield to liquid products and considerably reduce the halogen content. The sample with the highest polyolefin content achieved the highest liquid yield (70.6 wt.% at 460 °C) and the lowest chlorine content (160 ppm) among the investigated samples and, therefore, was the most suitable liquid to use as refinery feedstock. The effect of temperature on the pyrolysis of this sample was studied in the range of 430–490 °C. As the temperature increased the liquid yield increased and solid yield decreased, indicating that the conversion was maximized. At 490 °C, the pyrolysis oil with the highest calorific value (44.3 MJ kg−1) and paraffinic content (65% area), the lowest chlorine content (128 ppm) and more than 50 wt.% of diesel was obtained.

Reactivity controlled compression ignition (RCCI) is a highly efficient and clean combustion concept, which enables the use of a wide range of renewable fuels. Consequently, this promising dual fuel combustion concept is of great interest for realizing climate neutral future transport. RCCI is very sensitive for operating conditions and requires advanced control strategies to guarantee stable and safe operation. For real-world RCCI implementation, we face control challenges related to transients and varying ambient conditions. Currently, a multivariable air–fuel path controller that can guarantee robust RCCI engine operation is lacking. In this work, we present a RCCI engine controller, which combines static decoupling and a diagonal MIMO feedback controller. For control design, a frequency domain-based approach is presented, which explicitly deals with cylinder-to-cylinder variations using data-driven, cylinder-individual combustion models. This approach enables a systematic trade-off between fast and robust performance and gives clear design criteria for stable operation. The performance of the developed multivariable engine controller is demonstrated on a six-cylinder diesel-E85 RCCI engine. From experimental results, it is concluded that the RCCI engine controller accurately tracks the five desired combustion and air path parameters, simultaneously. For the studied transient cycle, this results in 12.8% reduction in NOx emissions and peak in-cylinder pressure rise rates are reduced by 3.8 bar/deg CA. Compared to open-loop control, the stable and safe operating range is increased from 25 ∘C up to 35 ∘C intake manifold temperature and maximal load range is increased by 14.7% up to BMEP = 14.8 bar

The aim of this paper is for the production of oils processed in refineries to come from the pyrolysis of real waste from the high plastic content rejected by the recycling industry of the Basque Country (Spain). Concretely, the rejected waste streams were collected from (1) a light packaging waste sorting plant, (2) the paper recycling industry, and (3) a waste treatment plant of electrical and electronic equipment (WEEE). The influence of pre-treatments (mechanical separation operations) and temperature on the yield and quality of the liquid fraction were evaluated. In order to study the pre-treatment effect, the samples were pyrolyzed at 460 °C for 1 h. As pre-treatments concentrate on the suitable fraction for pyrolysis and reduce the undesirable materials (metals, PVC, PET, inorganics, cellulosic materials), they improve the yield to liquid products and considerably reduce the halogen content. The sample with the highest polyolefin content achieved the highest liquid yield (70.6 wt.% at 460 °C) and the lowest chlorine content (160 ppm) among the investigated samples and, therefore, was the most suitable liquid to use as refinery feedstock. The effect of temperature on the pyrolysis of this sample was studied in the range of 430–490 °C. As the temperature increased the liquid yield increased and solid yield decreased, indicating that the conversion was maximized. At 490 °C, the pyrolysis oil with the highest calorific value (44.3 MJ kg−1) and paraffinic content (65% area), the lowest chlorine content (128 ppm) and more than 50 wt.% of diesel was obtained.

Carbon emissions are one of the primary drivers of climate change and the transport sector accounts for 24% of the global carbon emissions. A shift within the automobile industry towards more eco-friendly modes of transportation is hence needed. Vehicles powered by hydrogen are a carbon emissions-free mode of transportation and have been identified as a viable approach to de-carbonize the transport sector, yet, the number of hydrogen-powered vehicles on the roads in Sweden as of 2022 is relatively low compared to the rest of the world. The aim of this study was both to identify factors that are important for actors to invest in hydrogen technology within the transport sector, and to identify how the collaboration between different actors was formed during the adoption process. The study uses a multiple-case study research design where the five cases of Storuman, Mariestad, Sandviken, Trelleborg and Ljungby were selected. Data was collected through eleven semi-structured interviews over video calls. The study has examined the diffusion process of hydrogen technology within the transport sector of each case according to the diffusion of innovations theory. An analysis of the diffusion of hydrogen technology has not, to the best of my knowledge, been conducted in the examined cases. Gaining an understanding of these processes can provide guidance for other municipalities or actors who aims to reduce their emissions and can play an important role in achieving Sweden´s objective of becoming the world´s first fossil-free welfare nation. The findings of the study were that investments in hydrogen technology within the transport sector are currently not economically profitable. However, investments in the innovation were still motivated in terms of a relative environmental advantage, reception of financial funding, the will to take a leading role in the energy transition, geographical location, long-term economic benefits and indirect economic benefits which mainly include

The use of alternative fuels for engine applications has attracted a lot of attention due to increased concerns over the CO2 emissions generated by the combustion of fossil fuels. One promising example of such fuels is biodiesels for use in internal combustion engines, such as the Karanja Methyl Ester (KME). In this work, we report on numerical studies of spray combustion of a surrogate of KME via Large-Eddy Simulation. The surrogate fuel considered herein is a blend of n-dodecane (64.32%) and methyl butanoate (35.68%), which replicates the main characteristics of the actual gaseous KME biodiesel. The main objectives of this study is to investigate the properties of spray combustion of this surrogate and to compare them with those of standard diesel fuels. The computational setup follows closely the conditions of the reactive “Spray A” baseline defined by the Engine Combustion Network. Concerning the numerical methodology, we employ the Eulerian approach for the gaseous phase, coupled with Langrangian Particle Tracking for the motion of the liquid fuel droplets. For the breakup of the droplets we employ a modified version of the Taylor Analogy Breakup model that we presented recently1. Further, with regard to combustion modelling and turbulence-chemistry interaction, we employ the Flamelet-Generated Manifold (FGM) which is based on tabulated chemistry and in which the advancement of the reaction process and composition of the mixture is described in terms of certain control variables. Herein, we employ a new implementation of the FGM approach according to which the energy equation is cast in terms of the sensible enthalpy2. This allows the direct computation of the temperature and the temperature-dependent properties of the mixture, which results in significant computational savings. In this presentation we discuss our numerical predictions for key characteristics of the combustion process, such as ignition delay time, flame lift-off length and flame temperature, an

In a fast-moving world with high demand for deliveries of various goods, the need for high performing transportation systems and networks has grown rapidly. As a reaction, the number of trucks has increased, which together with other transport solutions to cover the need has caused a growth of CO2e emissions. Sustainability awareness has pushed companies to consider and implement more sustainable transportation solutions to reduce the environmental impact from transport. The purpose of this study is to analyze and identify the root causes of CO2e emissions in a transport, delivery network. An understanding of the common characteristics of transports causing the highest levels of emissions is provided with an analysis of distances, modalities and fuel types. Additionally, alternatives are simulated to compare the current network to a system with different solutions implemented. The study was performed by analyzing available literature of intermodal transportation systems, alternative fuel types and different modalities. Data for a full year was collected from Scania AB, cleaned and analyzed to identify the type of transport to study further. The characteristics were identified by forming geographical regions based on location and available infrastructure, divide the transports by legs and distances, and sort the transports by fuel types and modalities. As a result, several flows were identified as examples representing the network where the effects of making changes could be most accurately identified.Simulations were performed for exemplary flows providing results for four out of seven regions in the network. Available infrastructure for different modalities was considered for each region and alternative fuel types researched. Considering the possibilities within the regions, each flow was simulated with the available solutions in the region. Additionally, infrastructure potentially developing in the near future, was considered as an alternative in cases where curre, I en snabbföränderlig omvärld med en hög efterfrågan av olika varor har behovet av högpresternade transportsystem ökat drastiskt. Som en reaktion på detta har antalet lastbilar ökat signifikant vilket i sin tur, tillsammans med andra transportlösningar som ska täcka det växande behovet, har lett till ökande CO2-utsläpp. En ökad medvetenhet inom hållbarhet har tvingat företag att överväga och implementera mer hållbara transportlösningar för att minska miljöpåverkan inom transport. Syftet med denna studie är att analysera och identifiera grundläggande orsaker för CO2-utsläpp inom ett transport- och leveransnätverk.En förståelse för de gemensamma egenskaperna inom transport som orsakar de högsta nivåerna av utsläpp anges genom en analys av avstånd, modaliteter och typ av bränsle. Dessutom är alternativa lösningar simulerade för att jämföra det nuvarande nätverket mot ett system med andra implementationer.Studien genomfördes genom att analysera tillgänglig litteratur om intermodala transportsystem, alternativa sorter av bränsle och olika modaliteter. Data för ett helt år samlades in från Scania AB, rensades och analyserades för att identifiera vilken form av transport som skulle studeras vidare. Egenskaperna identifierades genom att bilda geografiska regioner utifrån läge och tillgänglig infrastruktur, uppdelade i längre och kortare sträckor, samt genom att sortera transporterna efter bränsletyp och modaliteter. Som ett resultat identifierades en grupp av flöden som exempel, vilka representerade nätverket och där effekterna av att göra förändringar kunde anses mest exakta. Simuleringar för exempelflöden utfördes och gav resultat till fyra av sju regioner inom nätverket. Tillgänglig infrastruktur för olika modaliteter övervägdes för varje region och olika bränsletyper undersöktes. Med tanke på de olika möjligheterna inom regionen simulerades varje flöde med de tillgängliga lösningarna i regionen. Dessutom ansågs infrastruktur som skulle kunna utvecklas inom snar framtid

In a fast-moving world with high demand for deliveries of various goods, the need for high performing transportation systems and networks has grown rapidly. As a reaction, the number of trucks has increased, which together with other transport solutions to cover the need has caused a growth of CO2e emissions. Sustainability awareness has pushed companies to consider and implement more sustainable transportation solutions to reduce the environmental impact from transport. The purpose of this study is to analyze and identify the root causes of CO2e emissions in a transport, delivery network. An understanding of the common characteristics of transports causing the highest levels of emissions is provided with an analysis of distances, modalities and fuel types. Additionally, alternatives are simulated to compare the current network to a system with different solutions implemented. The study was performed by analyzing available literature of intermodal transportation systems, alternative fuel types and different modalities. Data for a full year was collected from Scania AB, cleaned and analyzed to identify the type of transport to study further. The characteristics were identified by forming geographical regions based on location and available infrastructure, divide the transports by legs and distances, and sort the transports by fuel types and modalities. As a result, several flows were identified as examples representing the network where the effects of making changes could be most accurately identified.Simulations were performed for exemplary flows providing results for four out of seven regions in the network. Available infrastructure for different modalities was considered for each region and alternative fuel types researched. Considering the possibilities within the regions, each flow was simulated with the available solutions in the region. Additionally, infrastructure potentially developing in the near future, was considered as an alternative in cases where curre, I en snabbföränderlig omvärld med en hög efterfrågan av olika varor har behovet av högpresternade transportsystem ökat drastiskt. Som en reaktion på detta har antalet lastbilar ökat signifikant vilket i sin tur, tillsammans med andra transportlösningar som ska täcka det växande behovet, har lett till ökande CO2-utsläpp. En ökad medvetenhet inom hållbarhet har tvingat företag att överväga och implementera mer hållbara transportlösningar för att minska miljöpåverkan inom transport. Syftet med denna studie är att analysera och identifiera grundläggande orsaker för CO2-utsläpp inom ett transport- och leveransnätverk.En förståelse för de gemensamma egenskaperna inom transport som orsakar de högsta nivåerna av utsläpp anges genom en analys av avstånd, modaliteter och typ av bränsle. Dessutom är alternativa lösningar simulerade för att jämföra det nuvarande nätverket mot ett system med andra implementationer.Studien genomfördes genom att analysera tillgänglig litteratur om intermodala transportsystem, alternativa sorter av bränsle och olika modaliteter. Data för ett helt år samlades in från Scania AB, rensades och analyserades för att identifiera vilken form av transport som skulle studeras vidare. Egenskaperna identifierades genom att bilda geografiska regioner utifrån läge och tillgänglig infrastruktur, uppdelade i längre och kortare sträckor, samt genom att sortera transporterna efter bränsletyp och modaliteter. Som ett resultat identifierades en grupp av flöden som exempel, vilka representerade nätverket och där effekterna av att göra förändringar kunde anses mest exakta. Simuleringar för exempelflöden utfördes och gav resultat till fyra av sju regioner inom nätverket. Tillgänglig infrastruktur för olika modaliteter övervägdes för varje region och olika bränsletyper undersöktes. Med tanke på de olika möjligheterna inom regionen simulerades varje flöde med de tillgängliga lösningarna i regionen. Dessutom ansågs infrastruktur som skulle kunna utvecklas inom snar framtid

Optimization transportation cargo and passengers between ports and regions are very important, because industrial regions are located some distance from ports. The demand for energy request for the movement of transport is a necessity in the modern world. Transport and activity called transportation are used daily, everywhere, and a lot of energy is needed to power the various transport modes. Today different transport modes are being used to transport passengers and cargo. It is quite common to use road transport, which can transport passengers and cargo from door to door. Considering alternative possibilities (road, railway and/or inland waterway transport), it is important, based on theoretical and experimentation, to identify optimal solutions. In finding transport modes that are either most technically or economically effective, we could unearth possible solutions which would require minimal energy use. Unfortunately, with increased transportation, this often leads to traffic congestion on the roads, which requires additional energy (fuel). This situation generates requirements from many stakeholders in terms of finding ways to decrease the transportation time and energy (fuel) consumed by transport modes. A theoretical method evaluation is conducted on the optimal transportation possibility that minimizes transportation time and energy (fuel) use by employing graph theory, which is presented in this paper. The scientific contribution is the development of a transport modes comparative index, which is then used for evaluations. This paper presents possible alternative transportation conditions based on a multi-criteria evaluation system, proposes a theoretical basis for the optimal solutions from an eco-economic perspective that considers energy, and provides for experimental testing during a specific case study. The final results from the case study provide recommendations and conclusions. © 2022 by the authors., open access

Optimization transportation cargo and passengers between ports and regions are very important, because industrial regions are located some distance from ports. The demand for energy request for the movement of transport is a necessity in the modern world. Transport and activity called transportation are used daily, everywhere, and a lot of energy is needed to power the various transport modes. Today different transport modes are being used to transport passengers and cargo. It is quite common to use road transport, which can transport passengers and cargo from door to door. Considering alternative possibilities (road, railway and/or inland waterway transport), it is important, based on theoretical and experimentation, to identify optimal solutions. In finding transport modes that are either most technically or economically effective, we could unearth possible solutions which would require minimal energy use. Unfortunately, with increased transportation, this often leads to traffic congestion on the roads, which requires additional energy (fuel). This situation generates requirements from many stakeholders in terms of finding ways to decrease the transportation time and energy (fuel) consumed by transport modes. A theoretical method evaluation is conducted on the optimal transportation possibility that minimizes transportation time and energy (fuel) use by employing graph theory, which is presented in this paper. The scientific contribution is the development of a transport modes comparative index, which is then used for evaluations. This paper presents possible alternative transportation conditions based on a multi-criteria evaluation system, proposes a theoretical basis for the optimal solutions from an eco-economic perspective that considers energy, and provides for experimental testing during a specific case study. The final results from the case study provide recommendations and conclusions. © 2022 by the authors., open access

Optimization transportation cargo and passengers between ports and regions are very important, because industrial regions are located some distance from ports. The demand for energy request for the movement of transport is a necessity in the modern world. Transport and activity called transportation are used daily, everywhere, and a lot of energy is needed to power the various transport modes. Today different transport modes are being used to transport passengers and cargo. It is quite common to use road transport, which can transport passengers and cargo from door to door. Considering alternative possibilities (road, railway and/or inland waterway transport), it is important, based on theoretical and experimentation, to identify optimal solutions. In finding transport modes that are either most technically or economically effective, we could unearth possible solutions which would require minimal energy use. Unfortunately, with increased transportation, this often leads to traffic congestion on the roads, which requires additional energy (fuel). This situation generates requirements from many stakeholders in terms of finding ways to decrease the transportation time and energy (fuel) consumed by transport modes. A theoretical method evaluation is conducted on the optimal transportation possibility that minimizes transportation time and energy (fuel) use by employing graph theory, which is presented in this paper. The scientific contribution is the development of a transport modes comparative index, which is then used for evaluations. This paper presents possible alternative transportation conditions based on a multi-criteria evaluation system, proposes a theoretical basis for the optimal solutions from an eco-economic perspective that considers energy, and provides for experimental testing during a specific case study. The final results from the case study provide recommendations and conclusions. © 2022 by the authors., open access

Optimization transportation cargo and passengers between ports and regions are very important, because industrial regions are located some distance from ports. The demand for energy request for the movement of transport is a necessity in the modern world. Transport and activity called transportation are used daily, everywhere, and a lot of energy is needed to power the various transport modes. Today different transport modes are being used to transport passengers and cargo. It is quite common to use road transport, which can transport passengers and cargo from door to door. Considering alternative possibilities (road, railway and/or inland waterway transport), it is important, based on theoretical and experimentation, to identify optimal solutions. In finding transport modes that are either most technically or economically effective, we could unearth possible solutions which would require minimal energy use. Unfortunately, with increased transportation, this often leads to traffic congestion on the roads, which requires additional energy (fuel). This situation generates requirements from many stakeholders in terms of finding ways to decrease the transportation time and energy (fuel) consumed by transport modes. A theoretical method evaluation is conducted on the optimal transportation possibility that minimizes transportation time and energy (fuel) use by employing graph theory, which is presented in this paper. The scientific contribution is the development of a transport modes comparative index, which is then used for evaluations. This paper presents possible alternative transportation conditions based on a multi-criteria evaluation system, proposes a theoretical basis for the optimal solutions from an eco-economic perspective that considers energy, and provides for experimental testing during a specific case study. The final results from the case study provide recommendations and conclusions. © 2022 by the authors., open access

Optimization transportation cargo and passengers between ports and regions are very important, because industrial regions are located some distance from ports. The demand for energy request for the movement of transport is a necessity in the modern world. Transport and activity called transportation are used daily, everywhere, and a lot of energy is needed to power the various transport modes. Today different transport modes are being used to transport passengers and cargo. It is quite common to use road transport, which can transport passengers and cargo from door to door. Considering alternative possibilities (road, railway and/or inland waterway transport), it is important, based on theoretical and experimentation, to identify optimal solutions. In finding transport modes that are either most technically or economically effective, we could unearth possible solutions which would require minimal energy use. Unfortunately, with increased transportation, this often leads to traffic congestion on the roads, which requires additional energy (fuel). This situation generates requirements from many stakeholders in terms of finding ways to decrease the transportation time and energy (fuel) consumed by transport modes. A theoretical method evaluation is conducted on the optimal transportation possibility that minimizes transportation time and energy (fuel) use by employing graph theory, which is presented in this paper. The scientific contribution is the development of a transport modes comparative index, which is then used for evaluations. This paper presents possible alternative transportation conditions based on a multi-criteria evaluation system, proposes a theoretical basis for the optimal solutions from an eco-economic perspective that considers energy, and provides for experimental testing during a specific case study. The final results from the case study provide recommendations and conclusions. © 2022 by the authors., open access

The aim of this paper is for the production of oils processed in refineries to come from the pyrolysis of real waste from the high plastic content rejected by the recycling industry of the Basque Country (Spain). Concretely, the rejected waste streams were collected from (1) a light packaging waste sorting plant, (2) the paper recycling industry, and (3) a waste treatment plant of electrical and electronic equipment (WEEE). The influence of pre-treatments (mechanical separation operations) and temperature on the yield and quality of the liquid fraction were evaluated. In order to study the pre-treatment effect, the samples were pyrolyzed at 460 °C for 1 h. As pre-treatments concentrate on the suitable fraction for pyrolysis and reduce the undesirable materials (metals, PVC, PET, inorganics, cellulosic materials), they improve the yield to liquid products and considerably reduce the halogen content. The sample with the highest polyolefin content achieved the highest liquid yield (70.6 wt.% at 460 °C) and the lowest chlorine content (160 ppm) among the investigated samples and, therefore, was the most suitable liquid to use as refinery feedstock. The effect of temperature on the pyrolysis of this sample was studied in the range of 430–490 °C. As the temperature increased the liquid yield increased and solid yield decreased, indicating that the conversion was maximized. At 490 °C, the pyrolysis oil with the highest calorific value (44.3 MJ kg−1) and paraffinic content (65% area), the lowest chlorine content (128 ppm) and more than 50 wt.% of diesel was obtained.

Carbon emissions are one of the primary drivers of climate change and the transport sector accounts for 24% of the global carbon emissions. A shift within the automobile industry towards more eco-friendly modes of transportation is hence needed. Vehicles powered by hydrogen are a carbon emissions-free mode of transportation and have been identified as a viable approach to de-carbonize the transport sector, yet, the number of hydrogen-powered vehicles on the roads in Sweden as of 2022 is relatively low compared to the rest of the world. The aim of this study was both to identify factors that are important for actors to invest in hydrogen technology within the transport sector, and to identify how the collaboration between different actors was formed during the adoption process. The study uses a multiple-case study research design where the five cases of Storuman, Mariestad, Sandviken, Trelleborg and Ljungby were selected. Data was collected through eleven semi-structured interviews over video calls. The study has examined the diffusion process of hydrogen technology within the transport sector of each case according to the diffusion of innovations theory. An analysis of the diffusion of hydrogen technology has not, to the best of my knowledge, been conducted in the examined cases. Gaining an understanding of these processes can provide guidance for other municipalities or actors who aims to reduce their emissions and can play an important role in achieving Sweden´s objective of becoming the world´s first fossil-free welfare nation. The findings of the study were that investments in hydrogen technology within the transport sector are currently not economically profitable. However, investments in the innovation were still motivated in terms of a relative environmental advantage, reception of financial funding, the will to take a leading role in the energy transition, geographical location, long-term economic benefits and indirect economic benefits which mainly include

Reactivity controlled compression ignition (RCCI) is a highly efficient and clean combustion concept, which enables the use of a wide range of renewable fuels. Consequently, this promising dual fuel combustion concept is of great interest for realizing climate neutral future transport. RCCI is very sensitive for operating conditions and requires advanced control strategies to guarantee stable and safe operation. For real-world RCCI implementation, we face control challenges related to transients and varying ambient conditions. Currently, a multivariable air–fuel path controller that can guarantee robust RCCI engine operation is lacking. In this work, we present a RCCI engine controller, which combines static decoupling and a diagonal MIMO feedback controller. For control design, a frequency domain-based approach is presented, which explicitly deals with cylinder-to-cylinder variations using data-driven, cylinder-individual combustion models. This approach enables a systematic trade-off between fast and robust performance and gives clear design criteria for stable operation. The performance of the developed multivariable engine controller is demonstrated on a six-cylinder diesel-E85 RCCI engine. From experimental results, it is concluded that the RCCI engine controller accurately tracks the five desired combustion and air path parameters, simultaneously. For the studied transient cycle, this results in 12.8% reduction in NOx emissions and peak in-cylinder pressure rise rates are reduced by 3.8 bar/deg CA. Compared to open-loop control, the stable and safe operating range is increased from 25 ∘C up to 35 ∘C intake manifold temperature and maximal load range is increased by 14.7% up to BMEP = 14.8 bar

In order to reduce fossil fuel consumption of the Royal Netherlands Navy (RNLN) by 70% in 2050, the use of alternative fuels on the large naval surface vessels is examined. This paper examines the implications for the design and operational effectiveness of these vessels by performing two case studies of the Zeven Provinci¨en air defence and command frigate (LCF) and the Johan de Witt landing platform dock (LPD). In the case studies an operational analysis, a parametric design study, and an effectiveness assessment are performed on multiple proposed designs. Results showed that it is possible to reduce the fossil fuel consumption of the RNLN by almost 70%. This does affect the design of the vessels, however. It was also concluded that the LPD is more suitable for the application of low-energy-density fuels than the LCF, due to its missions requirements. Both the LPD and the LCF show a significant increase in displacement and fuel cost, but it is possible to reduce effects on the operational effectiveness to a minimum., Ship Design, Production and Operations

The offshore wind market is growing rapidly, and new offshore wind projects are being launched more than ever. To keep up with demand, parts for these wind turbines are being produced all over the world. To get all the parts needed to their destination on time, they must be transported on heavy transport vessels (HTVs). Today, business cases focused on maximizing profits dictate the design of these vessels. Despite the upcoming energy transition, the environmental impact of these vessels is usually neglected. Therefore, there is a need for a method to evaluate the economic and environmental performance of HTVs. One basis for such a method is Blended Design. This method is able to cope with market uncertainties in the early stages of ship design by expanding knowledge when design freedom is still high by combining market forecasts for offshore wind farms with multiple vessel designs. An uncertainty model then evaluates the financial performance of the vessels in the market, allowing designers to explore the performance on basic main dimensions of an offshore wind installation vessel. The main limitations of this method are that it is not able to optimize on environmental performance and evaluate the financial impact of alternative fuels. Due to growing concerns about climate change, Ulstein has seen an increase in requests for the use of alternative fuels in ship designs. For this research, methanol, ammonia and liquid hydrogen are being investigated as these alternative fuels are considered future-proof. The use of alternative fuels in ship design involves some adjustments to the Blended Design method. Due to the different gravimetric and volumetric densities of these alternative fuels, this has implications for the endurance of the ship design and the amount of cargo the ship can carry. Changing system and installation requirements and varying fuel costs also drastically alter the financial performance of alternative fuels on, Marine Technology

The current global fleet is still dependent on conventional fuels as energy source to transport goods to various places in the world. These conventional fuels, such as MGO or HFO, emit large amounts of greenhouse gasses and other pollutant emissions. Regulation concerning these emissions becomes stricter every day, therefore institutions and governments have established reduction targets. To accomplish these reductions, net zero alternative fuels are serious candidates to investigate. As a result of these developments, Thecla Bodewes Shipyards is interested in solutions to reduce these emissions for their general cargo vessel series. Therefore, the objective of this research is to select the most suitable alternative fuel power- and energy system for a 7000 DWT general cargo vessel. In order to accomplish this objective, a literature review concerning potential alternative fuels is performed. After the selection of methanol as alternative fuel, the object of study is defined with specific boundaries and assumptions of the model. For the comparison of the current power- and energy system with future power- and energy systems, performance indicators are established and calculated. Subsequently, a case study is performed in which three concept designs for storage of methanol and two power plant configurations are proposed based on suitable energy converters on methanol and electrical load balance of the vessel. This research concludes that the fuel consumption of the vessel increased by a factor 2.1-2.4, range decreased by respectively 35% and 45% and payload decreased by 70 tonnes. Concerning the application of a methanol power- and energy system on board of a 7000 DWT general cargo vessel, a SI-ICE power plant with methanol as main fuel seemed most feasible., Marine Technology | Maritime Operations and Management

Optimization transportation cargo and passengers between ports and regions are very important, because industrial regions are located some distance from ports. The demand for energy request for the movement of transport is a necessity in the modern world. Transport and activity called transportation are used daily, everywhere, and a lot of energy is needed to power the various transport modes. Today different transport modes are being used to transport passengers and cargo. It is quite common to use road transport, which can transport passengers and cargo from door to door. Considering alternative possibilities (road, railway and/or inland waterway transport), it is important, based on theoretical and experimentation, to identify optimal solutions. In finding transport modes that are either most technically or economically effective, we could unearth possible solutions which would require minimal energy use. Unfortunately, with increased transportation, this often leads to traffic congestion on the roads, which requires additional energy (fuel). This situation generates requirements from many stakeholders in terms of finding ways to decrease the transportation time and energy (fuel) consumed by transport modes. A theoretical method evaluation is conducted on the optimal transportation possibility that minimizes transportation time and energy (fuel) use by employing graph theory, which is presented in this paper. The scientific contribution is the development of a transport modes comparative index, which is then used for evaluations. This paper presents possible alternative transportation conditions based on a multi-criteria evaluation system, proposes a theoretical basis for the optimal solutions from an eco-economic perspective that considers energy, and provides for experimental testing during a specific case study. The final results from the case study provide recommendations and conclusions. © 2022 by the authors., open access

Sustainable aviation fuel is the primary tool through which the aviation sector can reduce greenhouse gas emissions in the next few decades.  Its ability to penetrate the jet fuel market is currently constrained by high prices, policy barriers and supply challenges. A federal tax credit is politically viable and has the potential to drastically increase sustainable aviation fuel production in the United States.  San Diego International Airport has the opportunity to become an early adopter of this fuel due to favorable California policies and proximity to sustainable aviation fuel suppliers.  Airport engagement with airlines and fuel suppliers will be necessary to promote San Diego as a welcome destination and partner in a sustainable aviation future.