Current Greenhous gas emissions (GHG) from maritime transport represent around 3% of global anthropogenic GHG emissions and will have to be cut in half by 2050 to meet Paris agreement goals. Liquefied natural gas (LNG) is by many seen as a potential transition fuel for decarbonizing shipping. Its favorable hydrogen to carbon ratio compared to diesel (marine gas oil, MGO) or bunker fuel (heavy fuel oil, HFO) translates directly into lower carbon emissions per kilowatt produced. However, these gains may be nullified once one includes the higher Well-to-tank emissions (WTT) of the LNG supply chain and the vessel’s un-combusted methane slip (CH₄) from its combustion engine. Previous studies have tended to focus either on greenhouse gas emissions from LNG in a Well-to-wake (WTW) perspective, or on alternative engine technologies and their impact on the vessel’s Tank-to-wake emissions (TTW). This study investigates under what conditions LNG can serve as a transition fuel in the decarbonization of maritime transport, while ensuring the lowest possible additional global warming impact. Transition refers to the process of moving away from fossil fuels towards new and low carbon fuels and engine technologies. Our results show: First, the importance of applying appropriate engine technologies to maximize GHG reductions; Second, that applying best engine technologies is not economically profitable; Third, how regulations could be amended to reward best engine technologies. Importantly, while the GHG reduction of LNG even with best engine technology (dual fuel diesel engine) are limited, ships with these engines can with economically modest modification switch to ammonia produced with renewable energy when it becomes available in sufficient amounts.

Liquified natural gas (LNG), with its low sulphur content, its favorable hydrogen-to-carbon ratio, and the lower nitrogen oxide emission when combusted compared to conventional fuels, fulfils all International Maritime Organization (IMO) air emission regulations. For the cruise industry, with their large number of customers and their high public visibility, LNG has therefore become a tempting option for new cruise ships. However, larger well-to-tank (WTT) emissions for the LNG supply chain as well as un-combusted methane (CH₄) from the ship’s engine might more than nullify any greenhouse gas (GHG) gains. Previous studies have shown very different GHG impacts from the use of LNG as a ship fuel. With climate change potentially being the largest threat to mankind, it is important that decisions with an impact on future GHG emissions are based on the best available knowledge within a sector and across sectors. The motivation for this study has therefore been to establish comparable GHG estimates for well-to-wake (WTW) emissions for LNG and traditional fuels in a transparent way. The results show that there is a need for adopting policies that can reduce the broader GHG emissions of shipping instead of CO₂ only, including the well-to-tank emissions of ship fuels. If not, we might end up with a large number of ships with GHG savings on paper only, while the real GHG emissions increases.

It is often assumed that the driving force behind autonomous ship discussions is reduction in crew cost or societal concerns like improved maritime safety due to reduction in human errors, better working conditions for crew in land-based control centers, or sustainability goals achieved through higher efficiency and lower emissions. But in assessing actual projects that are underway other factors also stand out. For the container ship Yara Birkeland, for example, the major drivers were reduction in local truck transport through urban areas and the realizing of a completely green electric transport. For ASKO cargo ferries, improved reliability of their inter-warehouse transport was a significant additional factor. This chapter will discuss possible societal benefits and potential drawbacks of autonomous ships, as presented in literature as well as from our own research particularly from the European Union (EU) projects Advanced, Efficient and Green Intermodal Systems (AEGIS) and Autonomous Shipping Initiative for European Waters (AUTOSHIP), and the Norwegian project “Smartere Transport”. The focus is on cargo transport, but some concerns for passenger transport will also be explored. The analysis is mostly qualitative, but some quantitative key performance indicators (KPI) will be proposed. The perspective is mainly Norwegian, a society with a high living standard and a sparsely populated nation, where advanced ship technology is a necessary part of life and in general positively regarded. Nevertheless, many of the observations are deemed highly applicable to other countries and regions. Keywords Autonomous shipping Autonomy Societal impact KPI