Renewable energy supply via carbon-based molecules – A techno-economic assessment of various import pathways

The EU's transition to net-zero greenhouse gas emissions (GHG) likely necessitates renewable energy imports. This paper assesses various import pathways for energy-rich “green” molecules into the EU, focusing on carbon-based molecules like “green” methanol and synthetic natural gas (SNG). These energy carriers, produced using hydrogen derived from renewable electricity and non-fossil CO₂, are compared with alternative import pathways, including liquid hydrogen, ammonia, and liquid organic hydrogen carriers (LOHCs). Different forms of final energy supply are analyzed, including pure hydrogen and hydrogen derivatives. Results show, that among the examined pathways relying on carbon-based molecules, energy imports via methanol with largely closed carbon cycles are particularly promising. A closed carbon cycle reduces the cost of energy supply with methanol by around 15 % compared to CO₂ provision via Direct Air Capture (DAC). For methanol, SNG and ammonia, direct use is more economical than reconversion into hydrogen. For pure hydrogen supply, importing gaseous hydrogen by pipeline or liquid hydrogen by ship results in the lowest hydrogen supply cost (∼0.15 €/kWh_H2,LHV). If hydrogen is imported via carriers, methanol or ammonia should be preferred, while SNG and LOHCs are less competitive.