Energy System Modelling of Discrete Commodity Shipping as a Renewable Energy Export Strategy
B. Kaya (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Stefan Pfenninger – Mentor (TU Delft - Energy and Industry)
Bryn Pickering – Graduation committee member (ETH Zürich)
Enno Schröder – Graduation committee member (TU Delft - Economics of Technology and Innovation)
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Abstract
This study investigates the feasibility of exporting renewable energy from isolated regions using aluminium as a physical energy export medium. Focusing on Iceland, a country with abundant hydropower and geothermal energy but lacking direct grid interconnection, this work evaluates whether aluminium production and maritime shipping can serve as a viable alternative to conventional electricity export via submarine cables. The aluminium effectively “embodies” renewable electricity used during smelting, enabling indirect energy export in the form of a commodity.
To capture the logistical complexity of this shipping-based strategy, an energy system model using the Calliope framework with customized Mixed-Integer Linear Programming (MILP) constraints is developed. These constraints allow the representation of discrete transport events, transit delays, fuel consumption, and shipment scheduling, which are dynamics that traditional energy models typically treat as continuous or overlook entirely. This approach is termed “discrete maritime transport modelling,” referring to the batch-based, non-continuous nature of shipping operations.
Two scenarios are assessed: (1) the discrete shipment of aluminium from Iceland to the Netherlands, and (2) continuous direct electricity transmission via a hypothetical high-voltage submarine cable. The comparative analysis evaluates total energy delivered and total system costs over a fixed operational horizon. Results show that aluminium shipping delivers far more energy (10,625 TWh) at significantly lower cost (33.85 million USD) than electricity transmission (689.76 GWh at 96.72 million USD), despite the latter’s advantage of real-time delivery and grid compatibility. Although these results are context-specific, they suggest that when largescale HVDC infrastructure is cost-prohibitive or geographically constrained, embodied energy export through industrial commodities may offer a competitive alternative.
Sensitivity analyses confirm the model’s robustness under variations in fuel use, system duration, and capacity assumptions. However, the aluminium pathway raises sustainability concerns not yet fully addressed in this study, including fossil fuel reliance in shipping and environmental impacts of metal production. Future work should expand the model to include emissions accounting, lifecycle energy analysis, and more refined operational behaviour of maritime logistics.
Overall, this report contributes a methodological innovation in energy system modelling and offers early evidence that industrial commodities can serve as flexible, scalable, and economically viable vectors for renewable energy export, particularly in geographically isolated, energy-rich regions.