Search Results (15)

To address greenhouse gas (GHG) emissions from the maritime sector, the European Union (EU) has introduced the FuelEU Maritime regulation to incentivize ships to adopt diversified compliance pathways and energy solutions. This study aims to determine the optimal alternative fuel configurations for dual-fuel ships of different types under environmental, economic, and regulatory constraints. An integrated environmental and cost assessment model from a well-to-wake (WtW) perspective to systematically evaluate the environmental benefits and economic feasibility of fossil-based, bio-based, and renewable electricity-based alternative fuels applied in dual-fuel ships. By incorporating the PROMETHEE II method within a multi-criteria decision analysis (MCDA) framework, together with the CRITIC objective weighting method, the study enables a robust ranking of alternative fuel configurations across three key dimensions: environmental performance, cost feasibility, and regulatory compliance. The results indicate that, regardless of ship type, the very low sulfur fuel oil (VLSFO) + marine gas oil (MGO) and VLSFO + methanol (MEOH) combinations fail to meet the GHG intensity targets for 2025–2050. Only the VLSFO + electrolytic liquid hydrogen (E-LH₂) and VLSFO + electrolytic ammonia (E-NH₃) configurations are compliant. Although e-fuels incur the highest annual costs, the EU compliance penalty associated with fossil fuels increases exponentially. In contrast, e-fuels retain long-term cost advantages, ultimately driving a sector-wide transition toward e-fuel-dominated energy structures by 2050. Their superior environmental performance and regulatory compatibility emerge as the core drivers of the maritime energy transition. Full article

This study investigates the environmental and economic performance of integrating a proton exchange membrane fuel cell, battery systems, and an organic Rankine cycle-based waste heat recovery system for ship electrification. The analysis examines an onboard ammonia decomposition system for hydrogen production and ammonia production pathways. Additionally, the study benchmarks the effectiveness of onboard ammonia decomposition against green hydrogen bunkering scenarios (H₂-BS). The analysis is based on data collected over two years from a bulk carrier provided by Laskaridis Shipping Co., Ltd. The environmental analysis includes well-to-wake emissions calculations. At the same time, economic performance is assessed through levelised cost of energy (LCOE) computations for 2025 and 2040, factoring in different fuel and carbon price scenarios. Consequently, the analysis utilises the Complex Proportional Assessment method to compare configurations featuring various ammonia production pathways across economic cases. The results indicate that green and pink ammonia feedstocks achieve maximum equivalent carbon dioxide reductions in the electrification plant of up to 47.28% and 48.47%, respectively, compared to H₂-BS and 95.56% and 95.66% compared to the base scenario. Ammonia decomposition systems prove more economically viable than H₂-BS due to lower storage and fuel costs, leading to competitive LCOE values that improve under higher carbon pricing scenarios. Full article

Driven by dual-carbon targets, marine engines are accelerating their transition towards low-carbon and zero-carbon. Ammonium–hydrogen fusion fuel is considered to be one of the most promising fuels for ship decarbonization. Using non-thermal plasma (NTP) catalytic ammonia on-line hydrogen production technology to achieve hydrogen supply is one of the most important means to guarantee the safety and effectiveness of hydrogen energy in the storage and transportation process. However, the efficiency of ammonia catalytic hydrogen production can be influenced to some extent by the presence of several factors, and the reaction mechanism is complex under the conditions of ship engine temperature emissions. This makes it difficult to realize the precise control of plasma catalytic hydrogen production from ammonia technology under temperature emission conditions, thus restricting an improvement in the ammonia conversion rate. In this study, a kinetic model of hydrogen production from ammonia catalyzed by NTP was established. The influencing factors (reaction temperature, pressure, N₂/NH₃ ratio in the feed gas) and mechanism path of hydrogen production from ammonia decomposition were explored. The results show that the increase in reaction temperature will lead to an increase in the ammonia conversion rate, while the ammonia conversion rate will decrease with the increase in reaction pressure and N₂/NH₃ ratio. When the reaction temperature is 300 K, the pressure is 1 bar, the feed gas is 98%N₂/2%NH₃, and the ammonia conversion rate is 16.7%. The reason why the addition of N₂ is conducive to the hydrogen production from NH₃ decomposition is that the reaction N₂(A3) + NH₃ => N₂ + NH₂ + H, triggered by the electron excited-state N₂(A3), is the main reaction for NH₃ decomposition. Full article

Ammonia has attracted much interest as a potential green and renewable hydrogen carrier or energy vector. Compared to hydrogen, ammonia offers several advantages. For example, ammonia has a significantly higher energy density and can be liquefied at room temperature at a moderate pressure of 8 bars. While ammonia can be cracked to supply hydrogen, it is also possible to convert it directly into high-temperature solid oxide fuel cells (SOFCs) to generate electricity. The Ship-FC project aims to install an ammonia-fed 2MW SOFC system on board the vessel Viking energy to demonstrate the feasibility of zero CO₂ emission shipping. For this NH₃ SOFC system, a catalytic afterburner is required to remove the hydrogen and ammonia present in the SOFC off-gas and to recover heat. The current study analysed the effects of different catalyst supports, with a focus on NO_X formation through the combustion of an SOFC off-gas surrogate. The study investigated the performance of catalysts based on the active metals, platinum and iridium, as well as the catalyst supports, Al₂O₃, SiO₂, and TiO₂. The results were correlated with catalyst characterisation data and ammonia TPD results. The investigations showed that the formation of NO_X was clearly affected by the nature of the catalyst support. The highest selectivity towards NO_X was observed for Al₂O₃, followed by SiO₂, and the lowest selectivity was observed for TiO₂. This trend was evident for the supported platinum and iridium catalysts and for the samples exclusively containing the support. The trend for N₂O formation was opposite to that of NO_X formation (TiO₂ > SiO₂ > Al₂O₃) in both the presence and absence of platinum or iridium. Full article

Decarbonizing maritime transport hinges on transitioning oil-fueled ships (98.4% of the fleet) to renewable and low-carbon fuel types. This shift is crucial for meeting the greenhouse gas (GHG) reduction targets set by the IMO and the EU, with the aim of achieving climate neutrality by 2050. Ammonia, which does not contain carbon atoms that generate CO₂, is considered one of the effective solutions for decarbonization in the medium and long term. However, the concurrent increase in nitrogen oxide (NO_x) emissions during the ammonia combustion cycle, subject to strict regulation by the MARPOL 73/78 convention, necessitates implementing solutions to reduce them through optimizing the combustion cycle. This publication presents a numerical study on the optimization of diesel and ammonia injection phases in a ship’s medium-speed engine, Wartsila 6L46. The study investigates the exhaust gas emissions and combustion cycle parameters through a high-pressure injection strategy. At an identified 7° CAD injection phase distance between diesel and ammonia, along with an optimal dual-fuel start of injection 10° CAD before TDC, a reduction of 47% in greenhouse gas emissions (GHG = CO₂ + CH₄ + N₂O) was achieved compared to the diesel combustion cycle. This result aligns with the GHG reduction target set by both the IMO and the EU for 2030. Additionally, during the investigation of the thermodynamic combustion characteristics of the cycle, a comparative reduction in NO_x of 4.6% was realized. This reduction is linked to the DeNO_x process, where the decrease in NO_x is offset by an increase in N₂O. However, the optimized ammonia combustion cycle results in significant emissions of unburnt NH₃, reaching 1.5 g/kWh. In summary, optimizing the combustion cycle of dual ammonia and diesel fuel is essential for achieving efficient and reliable engine performance. Balancing combustion efficiency with emission levels of greenhouse gases, unburned NH₃, and NO_x is crucial. For the Wartsila 6L46 marine diesel engine, the recommended injection phasing is A710/D717, with a 7° CAD between injection phases. Full article

The maritime industry needs sustainable, low-emission fuels to reduce the environmental impact. Ammonia is one of the most promising alternative fuels because it can be produced from renewable energy, such as wind and solar. Furthermore, ammonia combustion does not emit carbon. This review article covers the advantages and disadvantages of using ammonia as a sustainable marine fuel. We start by discussing the regulations and environmental concerns of the shipping sector, which is responsible for around 2% to 3% of global energy-related CO₂ emissions. These emissions may increase as the maritime industry grows at a compound annual growth rate of 4.33%. Next, we analyze the use of ammonia as a fuel in detail, which presents several challenges. These challenges include the high price of ammonia compared to other fossil fuels, the low reactivity and high toxicity of ammonia, NOx, and N₂O emissions resulting from incomplete combustion, an inefficient process, and NH₃ slipping. However, we emphasize how to overcome these challenges. We discuss techniques to reduce NOx and N₂O emissions, co-combustion to improve reactivity, waste heat recovery strategies, the regulatory framework, and safety conditions. Finally, we address the market trends and challenges of using ammonia as a sustainable marine fuel. Full article

This study proposes a feasible solution for boil-off gas (BOG) treatment to facilitate NH₃ fuel use by ocean-going ships, which is currently considered an alternative fuel for ships. Two systems were designed and analyzed for BOG in IMO Type-A NH₃ fuel storage tanks for 14,000 TEU container ships. First, BOG lost inside the storage tank minimized economic losses through the onboard re-liquefaction system. The total energy consumed by the system to process NH₃ gas generated in the fuel tank at 232.4 kg/h was 51.9 kW, and the specific energy consumption (SEC) was 0.223 kWh/kg. Second, NH₃ was supplied to the direct Low-Pressure Selective Catalytic Reduction (LP-SCR) system to treat marine pollutants generated by combustion engines. The feasible design point was determined by calculating the NH₃ feed flow rate using three methodologies. The energy consumed by the direct LP-SCR system was 3.89 and 2.39 kW, and the SEC was 0.0144 at 0.0167 kWh/kg at 100% and 25% load, respectively. The feasibility was indicated via economic analysis. Depending on the life cycle cost, the competitiveness of the re-liquefaction system depends on the price of NH₃, where a higher price yields a more economical solution. In conclusion, the direct LP-SCR system has a low overall cost because of its low energy consumption when supplying NH₃ and its reduced amount of core equipment. Full article

This study performed a technical–economic analysis for ship-based ammonia transportation to investigate the feasibility of international ammonia transportation. Ammonia is considered to be a vital hydrogen carrier, so the international trade in ammonia by ship will considerably increase in the future. This study proposed three scenarios for transporting ammonia from the USA, Saudi Arabia, and Australia to South Korea and employed an 84,000 m³ class ammonia carrier. Not only traditional very low sulfur fuel oil (VLSFO)/marine diesel oil (MDO) but also LNG and ammonia fuels were considered as propulsion and power generation fuels in the carrier. A life-cycle cost (LCC) model consisting of capital expenditure (CAPEX) and operational expenditure (OPEX) was employed for the cost estimation. The results showed that the transportation costs depend on the distance. The unit transportation cost from the USA to South Korea was approximately three times higher than that of Australia to South Korea. Ammonia fuel yielded the highest costs among the fuels investigated (VLSFO/MGO, LNG, and ammonia). When using ammonia fuel, the unit transportation cost was approximately twice that when using VLSFO/MDO. The fuel costs occupied the largest portion of the LCC. The unit transportation costs from Australia to South Korea were 23.6 USD/ton-NH3 for the LVSFO/MDO fuel case, 31.6 USD/ton-NH3 for the LNG fuel case, and 42.9 USD/ton-NH3 for the ammonia fuel case. This study also conducted a sensitivity analysis to investigate the influence of assumptions, including assumed parameters. Full article

Current efforts by the International Maritime Organization (IMO) to decarbonize the shipping sector have gained momentum, although the exact path to achieve this goal is currently unclear. However, it can be safely assumed that alternative cleaner and zero-carbon fuels will be key components in the strategy. In this work, three ship emission scenarios for 2025, 2040, and 2050 were developed that cover the area of the North and Baltic Seas. They aim at a fundamental transition in the usage of marine fuels towards ammonia as the mainly used fuel in 2050, via an intermediate step in 2040 with liquefied natural gas as the main fuel. Additionally, expected trends and developments for the shipping sector were implemented, i.e., a fleet growth by vessel size and number. Efficiency improvements were included that are in accordance with the Energy Efficiency Design Index of the IMO. The scenarios were created using a novel method based on modifications to a virtual shipping fleet. The vessels in this fleet were subject to decommission and renewal cycles that adapt them to the scenario’s target year. Emissions for this renewed shipping fleet were calculated with the Modular Ship Emission Modeling System (MoSES). With respect to ammonia engine technology, two cases were considered. The first case deals with compression ignition engines and marine gas oil as pilot fuel, while the second case treats spark ignition engines and hydrogen as the pilot fuel. The first case is considered more feasible until 2050. Reductions with the first case in 2050 compared to 2015 were 40% for ${\mathrm{CO}}_2$ emissions. However, ${\mathrm{CO}}_2$ equivalents were only reduced by 22%, with the difference mainly resulting from increased ${\mathrm{N}}_2\mathrm{O}$ emissions. ${\mathrm{NO}}_{\mathrm{X}}$ emissions were reduced by 39%, and different $\mathrm{PM}$ components and ${\mathrm{SO}}_2$ were between 73% and 84% for the same target year. The estimated ${\mathrm{NH}}_3$ slip from ammonia-fueled ships in the North and Baltic Seas was calculated to be 930 $\mathrm{Gg}$ in 2050. For the second ammonia engine technology that is considered more advanced, emission reductions were generally stronger and ammonia emissions smaller. Full article

There exists no single optimal way for transporting hydrogen and other hydrogen carriers from one port to the other globally. Its delivery depends on several factors such as the quantity, distance, economics, and the availability of the required infrastructure for its transportation. Europe has a strategy to invest in the production of green hydrogen in Africa to meet its needs. This study assessed the economic viability of shipping liquefied hydrogen (LH₂) and hydrogen carriers to Germany from six African countries that have been identified as countries with great potential in the production of hydrogen. The results obtained suggest that the shipping of LH₂ to Europe (Germany) will cost between 0.47 and 1.55 USD/kg H₂ depending on the distance of travel for the ship. Similarly, the transportation of hydrogen carriers could range from 0.19 to 0.55 USD/kg H₂ for ammonia, 0.25 to 0.77 USD/kg H₂ for LNG, 0.24 to 0.73 USD/kg H₂ for methanol, and 0.43 to 1.28 USD/kg H₂ for liquid organic hydrogen carriers (LOHCs). Ammonia was found to be the ideal hydrogen carrier since it recorded the least transportation cost. A sensitivity analysis conducted indicates that an increase in the economic life by 5 years could averagely decrease the cost of LNG by some 13.9%, NH₃ by 13.2%, methanol by 7.9%, LOHC by 8.03%, and LH₂ by 12.41% under a constant distance of 6470 nautical miles. The study concludes with a suggestion that if both foreign and local participation in the development of the hydrogen market is increased in Africa, the continent could supply LH₂ and other hydrogen carriers to Europe at a cheaper price using clean fuel. Full article

One of the consequences of the conflict in Ukraine relates to the growing shortfall in global ammonia production. There are additional negative global impacts on the availability of fertilizers and prices of ammonia (NH₃). The shortage in ammonia production does not only influence the agroindustry but also the global shipping industry, as ammonia is positioned as a promising zero-carbon fuel and as a storage and transport medium for hydrogen. There are plans underway to start ammonia production in Estonia to minimize the consequences of the import stop of Russian ammonia in the context of the Ukrainian crisis. This study investigated the Baltic Sea Region (BSR) ammonia market and analyzed the economic implications of building an ammonia plant within the BSR. Using fuzzy real options models as the conceptual framework, together with secondary data analysis, case studies and expert interviews, the authors chart possible courses for the construction of ammonia production facilities within the region. Based on the case of the NH₃ production plant, as well as the underlying distribution system, the study provides new economic perspectives for lower carbonization for the shipping industry, an attempt at creating a model for other European regions toward climate change mitigation. Full article

This study proposed the integrated design of an NH₃ fuel supply system and a re-liquefaction system for an ocean-going NH₃-fueled ship. The target ship was a 14,000 TEU large container ship traveling from Asia to Europe. The NH₃ fuel supply system was developed to feed the liquid fuel at 40 °C and 80 bar and cope with the re-circulated fuel with the sealing oil. Its power consumptions and SECs ranged from 56.4 to 157.5 kW and from 0.0063 to 0.009 kWh/kg, respectively. An onboard re-liquefaction system with a vapor compression refrigeration cycle was also designed to liquefy the BOG from the fuel tank. The re-liquefaction system’s exergy efficiency and SEC were 34.71% and 0.224 kWh/kg, respectively. The equipment with the most exergy destruction was the heat exchangers, accounting for 60% of the total exergy destruction. NPV analysis found that it is recommended to introduce the re-liquefaction system to the target ship. At the NH₃ price of USD 250/ton, the reasonable cost of the re-liquefaction system is less than USD 1 million. According to LCC, NH₃ fuel is economically feasible if the carbon tax is more than USD 80/ton and the NH₃ price is around USD 250/ton. Full article

Following the International Maritime Organization (IMO), in order to safeguard the realization of the Paris Agreement on climate protection, greenhouse gas (GHG) emissions have to be reduced by 50% by the year 2050. This objective shall be reached by decarbonization of maritime traffic, which is why ship operators currently increasingly search for alternative fuels. Moreover, since the start of the Ukrainian war in February 2022, this issue of alternative fuels has gained central importance in political agendas. A promising candidate for clean shipping that meets the IMO goals is ammonia since it is a carbon-free fuel. Ammonia (NH₃) shows good advantages in handling and storage, and it ensures long sea voyages without any significant loss in cargo space for a reasonable price. Hence, ammonia has the potential to improve the environmental footprint of global shipping enormously. Induced by the introduction of stricter regulations in the so-called emission control areas (ECAs) in Northern Europe in 2015 as well as the renewed global sulfur cap, which entered into force in 2020, ship operators had to decide between different compliance methods, among which the most popular solutions are related to the use of expensive low-sulfur fuel oils, newbuilds and retrofits for the usage of liquefied natural gas (LNG) or the installation of scrubber technology. A change to ammonia as a marine alternative fuel represents an additional novel future option, but the successful implementation depends on the availability of NH₃ in the ports, i.e., on the installation of the maritime NH₃ infrastructure. Currently, the single German NH₃ terminal with maritime access is located in Brunsbüttel, the western entrance to Kiel Canal. The distribution of NH₃ from the existing NH₃ hub to other German ports can be analyzed by the mathematical model of an inventory routing problem (IRP) that is usually solved by combinatorial optimization methods. This paper investigates the interrelated research questions, how the distribution of marine NH₃ fuel can be modeled as an IRP, which distribution mode is the most economic one for the German ports and which modal mix for the NH₃ supply leads to the greenest distribution. The results of this paper are empirically validated by data that were collected in several EU projects on sustainable supply chain management and green logistics. The paper includes a special section that is dedicated to the discussion of the economic turbulences related to the Ukrainian war together with their implications on maritime shipping. Full article

Nowadays, maritime air pollution is regarded as a severe threat to coastal communities’ health. Therefore, many policies to reduce air pollution have been established worldwide. Moreover, there has been a shift in policy and research attention from greenhouse gases, especially CO₂, to other air pollutants. To address the current local environmental challenges, this research analyzes the non-greenhouse gas emissions inventory (CO, NO_x, SO_x, PM, VOC, and NH₃) from ships in the second biggest port in Korea, the Port of Incheon (POI). A bottom-up activity-based methodology with real-time vessel activity data produced by the Vessel Traffic Service (VTS) is applied to obtain reliable estimations. NO_x and SO_x dominated the amount of emission emitted from ships. Tankers, general cargo ships, cruise ships, and container ships were identified as the highest sources of pollution. Based on the above results, this study discusses the need for long-term policies, such as the designation of a local emission control area (ECA) and the establishment of an emission management platform to reduce ship-source emissions. Furthermore, this study elucidates that significant emissions come from the docking process, ranging from 33.9% to 42.0% depending on the type of pollutant when only the auxiliary engines were being operated. Therefore, short-term solutions like applying exhausted gas cleaning systems, using on-shore power supplies, reducing docking time, or using greener alternative fuels (e.g., liquefied natural gas or biofuels) should be applied and motivated at the POI. These timely results could be useful for air quality management decision-making processes for local port operators and public agencies. Full article

Vanadium-based catalysts are mainly used for marine diesel exhaust denitration. However, their poor catalytic ability at low temperature and poor sulfur tolerance, as well as high toxicity and cost, are big turnoffs. AC (Activated carbon) exhibits good adsorption capacity and catalytic ability in denitration because of its high specific surface area and chemical activity. In this paper, coal-based AC was used for simulating diesel exhaust denitration in different conditions. The results show that the NO removal ability of AC is poor in an NO/N₂ system. The NO₂ removal ability is excellent in an NO₂/N₂ system, where NO is desorbed. The NOx removal efficiency is 95% when the temperature is higher than 200 °C in an NO₂/NH₃/N₂ system. When the temperature is lower than 100 °C, AC can catalytically oxidize NO to NO₂ in an NO₂/O₂/N₂ system. The near-stable catalytic efficiencies of AC for a slow SCR (Selective Catalytic Reduction) reaction, a standard SCR reaction, and a fast SCR reaction at 300 °C are 12.1%, 31.6%, and 70.8%, respectively. When ships use a high-sulfur fuel, AC can be used after wet scrubber desulfurization to catalytically oxidize NO to NO₂ at a low temperature. When ships use a low-sulfur fuel, AC can be used as a denitration catalyst at high temperatures. Full article