No abstract

In the original version of the book, the legend of the Fig. 2.2 was corrected. The chapter and book have been updated with the changes.

Estimates for the greenhouse gas emissions caused by maritime transportation account for approx. 870 million tonnes of CO2 tonnes in 2018, increasing the awareness of the public in general and requiring the development of alternative propulsion systems and fuels to reduce them. In this context, the project HySeas III is developing a hydrogen and fuel cell powered roll-on/roll off and passenger ferry intended for the crossing between Kirkwall and Shapinsay in the Orkney Islands in Scotland, a region which currently has an excess of wind and tidal power. In order to explore the environmental aspects of this alternative, a life cycle assessment from cradle to end-of-use using the ReCiPe 2016 method was conducted, contrasting the proposed prototype developed within the project against a conventional diesel ferry and a diesel hybrid ferry. The results show that the use of hydrogen derived from wind energy and fuel cells for ship propulsion allow the reduction of greenhouse gas emissions of up to 89% compared with a conventional diesel ferry. Additional benefits are lower stratospheric ozone depletion, ionizing radiation, ozone formation, particulate matter formation, terrestrial acidification and use of fossil resources. In turn, there is an increase in other impact categories when compared with diesel electric and diesel battery electric propulsion. Additionally, the analysis of endpoint categories shows less impact in terms of damage to human health, to the ecosystems and to resource availability for the hydrogen alternative compared to conventional power trains.

The International Maritime Organization (IMO) established new strategies that could lead to a significant reduction in the carbon footprint of the shipping sector to address global warming. A major factor in achieving this goal is transitioning to renewable fuels. This implies a challenge, as not only ship-innovative solutions but also a complete low-carbon fuel supply chain must be implemented. This work provides a method enabling the exploration of the potential of low-carbon fuel technologies for specific shipping routes up to larger sea regions. Several aspects including vessel sizes, impact of weather and shipping routes, emissions savings and costs are considered. The local energy use is determined with proven bottom-up prediction methods based on ship positioning data from the Automatic Identification System (AIS) in combination with weather and ship technical data. This methodology was extended by an approach to the generation of a basic low-carbon fuel system topology that enables the consideration of local demand profiles. The applicability of the proposed approach is discussed at hand via a case study on Roll-on/Roll-off passenger and cargo (RoPax) ferries transitioning from conventional fuels to a compressed hydrogen fuel system. The results indicate a potential reduction in emissions by up to 95% and possible system sizes and costs.

The energy transition and associated objectives like climate change mitigation, economic efficiency, social acceptance and security of supply require technologies that are sustainable. With the help of a Life Cycle Sustainability Assessment (LCSA), such a holistic evaluation of energy technologies can be carried out. This in itself is very complex, since criteria of the different sustainability dimensions have to be compiled and integrated to give an overall result. However, LCSA often only considers the current development status of technologies and not their potential future developments. Particularly in the case of emerging technologies, possible future improvements or even negative impacts may occur in the course of technology development, which could significantly change the initial LCSA results. An early consideration of future developments of technologies in the context of so-called prospective LCSA is therefore highly relevant, but also of high complexity and associated with uncertainties. We evaluated how this complex topic of prospectivity has been dealt with in the LCSA community so far by conducting a literature review. Focusing on LCSA of energy technologies, we present our findings related to commonly used prospective methods and data, the underling motivation of their application as well as research gaps and potentials for further development.