Initial technology assessment of aluminium as an energy carrier in shipping

• Aluminium may become a suitable future energy carrier in shipping. • The use of aluminium is associated with several advantages and disadvantages. • Several challenges need to be overcome to make aluminium fully suitable. • Many of the challenges can potentially be solved. This paper presents an initial technology assessment of the suitability of using aluminium as an energy carrier in shipping. The overall conclusion is that aluminium may become a suitable future energy carrier. Several advantages of using aluminium exist, including high theoretical energy densities, high resource availability, opportunity for circularity, and future potential for low lifecycle environmental impact. However, several disadvantages exist, including the need for an activation method, byproduct handling, uncertain economic viability, and low technology readiness for both the energy utilisation from aluminium and environmentally friendly aluminium production. Additionally, several disadvantages specifically related to the activation method exist, mainly affecting the choice of activation method. Certain aluminium types are more suitable to use than others, and the priority order is: 1. waste that cannot easily be recycled through traditional recycling methods, 2. other waste types, and 3. virgin aluminium. However, fully replacing the fossil fuel use in shipping requires about 300 Mton aluminium/year. Waste can only meet 3–17% of this demand, therefore is an increased virgin aluminium production needed. Virgin production of 300 Mton aluminium/year requires about 6,000 TWh/year, which is 2.3 times higher than shipping’s current fossil fuel use. This requires extensive build-out of renewable energy supply, which is well within the technical and economic potentials for renewable energy. Several challenges need to be overcome to make aluminium fully suitable as an energy carrier, including technology and infrastructure development, maximising circularity, reducing lifecycle environmental impact, and improving cost-competitiveness. Many of these challenges can potentially be solved.