Environmental emissions from the maritime sector, including CO₂, NO_x, and SO_x, contribute significantly to global air pollution and climate change. The International Maritime Organization (IMO) has set a target to reduce greenhouse gas emissions from international shipping to reach zero GHG by 2050 compared to 2008 levels. To meet these goals, the IMO strongly encourages the transition to alternative fuels, such as hydrogen, ammonia, and biofuels, as part of a broader decarbonization strategy. This study presents a comparative analysis of converting conventional diesel engines to dual-fuel systems utilizing alternative fuels such as methanol or natural gas. The methodology of this research is based on theoretical calculations to estimate various types of emissions produced by conventional marine fuels. These results are then compared with the emissions generated when using methanol and natural gas in dual-fuel engines. The analysis is conducted using the EVER ALOT container ship as a case study. The evaluation focuses on both environmental and economic aspects of engines operating in natural gas–diesel and methanol–diesel dual-fuel modes. The results show that using 89% natural gas in a dual fuel engine reduces nitrogen oxides (NO_x), sulfur oxides (SO_x), carbon dioxide (CO₂), particulate matter (PM), and carbon monoxide (CO) pollutions by 77.69%, 89.00%, 18.17%, 89.00%, and 30.51%, respectively, while the emissions percentage will be 77.78%, 91.00%, 54.67%, 91.00%, and 55.90%, in order, when using methanol as a dual fuel with percentage 91.00% Methanol. This study is significant as it highlights the potential of natural gas and methanol as viable alternative fuels for reducing harmful emissions in the maritime sector. The shift toward these cleaner fuels could play a crucial role in supporting the maritime industry’s transition to low-emission operations, aligning with global environmental regulations and sustainability goals.

This paper represents the effects of geometry and design of an oscillating water column energy converter air chamber on the airflow response. The primary goal of this research is to use different shapes of air chambers, such as rectangular, cylindrical, and conical air chambers with varying cross sections, to optimize the air velocity entering the turbine, to obtain the maximum power available in a progressive wave with a constant period and wavelength. Modeling and numericalsimulation are performed by using the commercial software ANSYS. Since this paper is concerned with the effect of air flow velocity, a vent is located at the chamber's outlet rather than a turbine. In order to obtain the exit air velocity results, the wave system air characteristics results are applied as an input air flowfor three air chamber cases. The results show that the air velocity flow increasedsignificantly from 7.14 m/s in the rectangular air chamber to 10.4 m/s in cylindrical air chamber and reached a maximum of 14.2 m/s in the conical airchamber.

One of the main causes of climate change and global warming is greenhouse gas emissions. Livestock makes up 15% of the world's greenhouse gases (GHG), whereas maritime shipping accounts for 3%. Cattle can produce about 500 grams of methane a day per cow. This study demonstrates that livestock ships are an extremely high source of methane emissions. This study also offers innovative scientific techniques for lowering methane gas emissions from livestock ships. The MV Gelbray Express Livestock ship is selected to investigate the overall emissions generated by the main engine and the livestock on board. Main engine CO2 emissions and livestock CO2 equivalent emissions are theoretically calculated during 24-hour sailing under engine full load and livestock full capacity. The study revealed that livestock CO2 equivalent emissions account for 43% of the total CO2 emissions emitted by the engine and the livestock. To decrease livestock methane emissions, ZELP (Zero Emissions Livestock Project) has patented a unique catalytic technique for capturing and neutralizing methane generated during enteric fermentation in ruminant animals such as cows. Theoretical results show that using the ZELP mask reduces CO2 equivalent emissions by 58 000 kg per day at a livestock capacity of 4000 cattle onboard the MV Gelbray Express Livestock ship.

Global warming and air pollution are undoubtedly the major issues of our time. As livestock is considered the main source of protein and dairy products and one of the main food sources for humanity, in some regions of the world, livestock vessels serve as the main logistical means of transportation. Reducing emissions from vessels is vital to ensure animal welfare and livestock health. The vessel MV Ganado Express was chosen to evaluate the overall emissions resulting from the main engine during a 24-hour navigation period under full engine load. This study aims to develop an approach to reduce greenhouse gas emissions using hydrogen proton exchange membrane fuel cells as an alternative to the conventional fossil fuel-powered main engine. The study indicates that replacing the ship's conventional main engine with hydrogen proton exchange membrane fuel cells can mitigate CO2 emissions by 10,200 kg, NOx by 1,637 kg, and SOX by 66 kg during a 24-hour sailing period under an engine load of 6,090 kW. During the same sailing conditions, the fuel consumption reduction when using hydrogen proton exchange membrane fuel cells is 62% lower than the fuel consumption when using a conventional diesel engine. Keywords: climate change; International Maritime Organization; zero emissions livestock ships. Viabilidade da utilização de células de combustível de hidrogênio em navios de transporte de gado para mitigar as emissões de gases de efeito estufa RESUMO: O aquecimento global e a poluição do ar são, sem dúvida, os grandes problemas atuais. Como o gado é considerado a principal fonte de proteína e laticínios e uma das principais fontes de alimento da humanidade, em alguns regioes do mundo, os navios de gado servem como os principais meios logisticos de transporte. Reduzir as emissões dos navios é vital para garantir o bem-estar animal e a saúde do gado. O navio MV Ganado Express foi escolhido para avaliar as emissões gerais resultantes do motor principal durante um período de navegação de 24 horas sob carga total do motor. Este estudo visa desenvolver uma abordagem para reduzir as emissões de gases de efeito estufa utilizando células de combustível de membrana de troca de prótons de hidrogênio como uma alternativa ao motor principal convencional movido a combustível fóssil. O estudo indica que a substituição do motor principal convencional do navio por células de combustível de membrana de troca de prótons de hidrogênio pode mitigar as emissões de CO2 em 10.200 kg, de NOx em 1.637 kg e de SOX em 66 kg durante o período de navegação de 24 horas sob uma carga de motor de 6.090 kW. Durante as mesmas condições de navegação, a redução do consumo de combustível durante o uso de células de combustível de membrana de troca de prótons de hidrogênio é 62% menor do que o consumo de combustível durante o uso do motor diesel convencional. Palavras-chave: mudanças climáticas; Organização Marítima Internacional; navios de gado com emissão zero.

Hydrogen appears in almost every maritime decarbonization roadmap, yet it barely sails: 19 vessels against more than 1600 powered by liquefied natural gas. This study combines an analysis of the global alternative-fueled fleet and orderbook (3094 fuel-vessel records) with an assessment of 26 international and European governance units, two of which are documented absences of an instrument, grouped into the seven conditions a hydrogen vessel needs to be built, certified, crewed, insured, financed and refueled. None of the 26 fully covers the condition it addresses, and the deficits run across all seven domains. Nor does binding demand regulation reach hydrogen where it is currently viable: the tonnage threshold it applies makes eligible nine out of ten LNG or methanol vessels and only two out of ten hydrogen vessels, a difference that narrows but does not close once adjusted for vessel segment. We term this pattern governance misalignment: conditions that must be met simultaneously but advance at different speeds, with unequal legal force, with ambiguous signals, and across fleet segments that do not coincide. The obstacle is not the absence of regulation but its lack of synchronization, a diagnosis replicable for any fuel whose deployment depends on several regulatory domains.

With the global population projected to reach nearly 10 billion by 2050, the demand for animal products is expected to rise significantly. A less recognized source of emissions in this supply chain is livestock maritime transport, which moves millions of animals worldwide and emits large amounts of CO₂ and other pollutants. This study focuses on reducing the environmental impact of ships through cleaner fuels, efficient routing, and improved onboard power systems. Ship emissions pose a significant global challenge due to their detrimental impact on the environment, especially in terms of contributing to atmospheric global warming. To address this, the International Maritime Organization (IMO) has prioritized environmental protection, aiming to cut exhaust emissions by at least 50% by the year 2050. One of the key strategies proposed by the IMO is the adoption of alternative marine fuels, such as natural gas and methanol, in place of traditional fossil fuels. This paper presents a comparative analysis of converting conventional diesel engines into dual-fuel engines that run on either methanol or natural gas. The study focuses on the economic aspects of both the natural gas and methanol dual-fuel systems. According to the findings, the use of natural gas results in cost savings of $275.546/ton for NOx, $11,358.610/ton for SOx, $29.0853/ton for CO2, and $8,518.962/ton for CO. In comparison, methanol offers cost reductions of $362.687/ton for NOx, $14,638.436/ton for SOx, $12.736/ton for CO2, and $6,127.717/ton for CO. The study underscores the environmental and economic advantages of using natural gas and methanol as cleaner alternatives in the maritime sector. The results indicate that adopting these fuels could significantly lower emissions from ships and support broader global sustainability goals. Keywords: dual-fuel engine; IMO regulations; methanol; natural gas; ship emission reduction.