Towards sustainable shipping: Evaluating the environmental impact of electrofuels

Sammanfattning: The global, local, and regional environment is under pressure from human activity. Changes in the environment can be beneficial and strived for, but environmental and health problems need to be considered when we design human activities. Shipping is a human activity causing emissions to air, water, and soil, which has direct and indirect effects on the environment. New fuels and propulsion technologies are required to lower the emissions from the shipping sector and reduce the impact on, for example, climate change. Fuels produced through electricity, water, and carbon dioxide, so-called electrofuels, is one group of fuels suggested to reduce the climate impact of shipping. This thesis focuses on the emissions from ships and their impacts on the environment when vessels move to electrofuels. This licentiate thesis aims to study the potential impact on the natural environment from using electrofuels onboard vessels and to explore which factors act as the main influencers on the natural environment and human health. Life cycle assessment was selected to address these questions, and through case study application the first assessment of an electrofuel in the context of shipping was performed. Through a techno-environmental system approach, critical flows between the shipping fuel life cycle and the environment were identified. The result points towards reductions of climate change impacts if renewable energy is used and CO2 is captured from a source not acting as a driver of fossil fuel extraction. Potential trade-offs were identified as electrofuels could lead to higher pressure on human health than today’s conventional fuels. The extent of these trade-offs is uncertain and affected by limitations in the method approach to the life cycle assessment of marine fuels. Suggestions on how to address these uncertainties, such as detailed system boundary definitions, are brought forward and analyzed based on the current state-of-the-art. The findings discussed in this licentiate thesis aim to promote further discussion around how to assess emerging fuel and propulsion technologies and the potential impact of future marine fuels.