Naval traffic is highly dependent on depleting fossil resources and causes significant greenhouse gas emissions. At the same time, marine transportation is a major backbone of world trade. Thus, alternative fuel concepts are highly needed. Different fuels such as ammonia, methanol, liquefied natural gas and hydrogen have been proposed. For some of them, first prototype vessels have been in operation. However, practical experience is still limited. Most studies so far focus on aspects such as efficiency and economics. However, particularly in marine applications, reliability of propulsion systems is of utmost importance, because failures on essential ship components at sea pose a huge safety risk. If the respective components lose their functionality, repair can be much more challenging due to large distances to dockyards and the complicated transport of spare parts to the ship. Consequently, evaluation of reliability should be a core element of system analysis for new marine fuels. In this study, reliability was studied for four potential fuels. The analysis involved several steps: estimation of overall failure rates, identification of most vulnerable components and assessment of criticality by including severity of fault events. On the level of overall failure rate, ammonia is shown to be very promising. Extending the view over a pure failure rate-based evaluation shows that other approaches, such as LOHC or methanol, can be competitive in terms of reliability and risk. As different scenarios require different weightings of the different reliability criteria, the conclusion on the best technology can differ. Relevant aspects for this decision can be the availability of technical staff, high-sea or coastal operation, the presence of non-naval personnel onboard and other factors. The analysis allowed to compare different alternative marine fuel concepts regarding reliability. However, the analysis is not limited to assessment of overall failure rates, but can also help to identify critical elements that deserve attention to avoid fault events. As a last step, severity of the individual failure modes was included. For the example of ammonia, it is shown that the decomposition unit and the fuel cell should be subject to measures for increasing safety and reducing failure rates.

中文翻译：

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船舶替代燃料应用技术的技术可靠性

海军交通高度依赖消耗的化石资源，并导致大量的温室气体排放。同时，海上运输是世界贸易的主要支柱。因此，非常需要替代燃料的概念。已经提出了不同的燃料，例如氨、甲醇、液化天然气和氢气。对于其中一些，第一艘原型船已经投入使用。然而，实践经验仍然有限。迄今为止，大多数研究都集中在效率和经济等方面。然而，特别是在船舶应用中，推进系统的可靠性至关重要，因为海上重要船舶部件的故障会带来巨大的安全风险。如果相应的组件失去其功能，由于到船坞的距离很远以及将备件运输到船上的复杂性，维修可能更具挑战性。因此，可靠性评估应该是新船用燃料系统分析的核心要素。在这项研究中，研究了四种潜在燃料的可靠性。分析包括几个步骤：估计总体故障率、识别最易受攻击的组件以及通过包括故障事件的严重性来评估关键性。在整体故障率水平上，氨被证明是非常有前途的。将观点扩展到基于纯故障率的评估表明其他方法，例如 LOHC 或甲醇，在可靠性和风险方面具有竞争力。由于不同的场景需要不同的可靠性标准的不同权重，关于最佳技术的结论可能会有所不同。该决定的相关方面可能是技术人员的可用性、公海或沿海作业、船上非海军人员的存在和其他因素。该分析允许在可靠性方面比较不同的替代船用燃料概念。然而，分析不仅限于对整体故障率的评估，还有助于识别值得关注的关键要素，以避免发生故障事件。作为最后一步，包括各个故障模式的严重性。以氨为例，分解单元和燃料电池应采取措施以提高安全性和降低故障率。船上非海军人员的存在和其他因素。该分析允许在可靠性方面比较不同的替代船用燃料概念。然而，分析不仅限于对整体故障率的评估，还有助于识别值得关注的关键要素，以避免发生故障事件。作为最后一步，包括各个故障模式的严重性。以氨为例，分解装置和燃料电池应采取措施以提高安全性和降低故障率。船上非海军人员的存在和其他因素。该分析允许比较不同的替代船用燃料概念的可靠性。然而，分析不仅限于对整体故障率的评估，还可以帮助识别值得关注的关键要素，以避免发生故障事件。作为最后一步，包括各个故障模式的严重性。以氨为例，分解装置和燃料电池应采取措施以提高安全性和降低故障率。但也有助于识别值得关注的关键要素，以避免发生故障事件。作为最后一步，包括各个故障模式的严重性。以氨为例，分解单元和燃料电池应采取措施以提高安全性和降低故障率。但也有助于识别值得关注的关键要素，以避免发生故障事件。作为最后一步，包括各个故障模式的严重性。以氨为例，分解单元和燃料电池应采取措施以提高安全性和降低故障率。