Energy efficiency and economic assessment of imported energy carriers based on renewable electricity

The production of energy carriers based on renewable electricity via the Power-to-X (PtX) approach holds the key for a holistic transformation of our global industries from fossil fuels towards renewable energy sources. To compete with cheap fossils, PtX products demand energy-efficient processes and low-cost renewable electricity. Therefore, the import of PtX products from countries with high renewable energy potentials to countries with high energy demand presents a promising pathway. However, the question which set of PtX products qualifies as suitable for long-distance transport has not yet been answered. In this context, this paper assesses the energy and cost efficiency of five PtX energy carriers (methane, methanol, ammonia, liquefied hydrogen and hydrogen bound in LOHC). Furthermore, we evaluate the influence of fluctuating renewables, availability of water and transport distance in a case study for large-scale PtX production in Morocco. Our results show that the evaluated PtX pathway efficiencies vary between 40–52% (base cases) and 44–58% (optimistic cases). None of the pathways assessed is significantly affected in its overall efficiency by a ship transport over an exemplary distance of 4000 km. However, for longer transport distances the cost difference between the assessed pathways increases. The production cost of the PtX energy carriers (124–156 € per MWh) depends on the availability of excess heat, energy density of the product and, if required, liquefaction efforts. In summary, the paper reveals that the long-distance transport and import of PtX products present an interesting option for the ongoing integration of renewable electricity into our energy system and industries. The petrochemical and steel industries in particular, as well as heavy goods transport, shipping and aviation, will be highly dependent on these imported synthetic energy sources.