A recent paper proposes an innovative solution to one of the challenges of establishing a global hydrogen economy: transporting hydrogen by sea. Hydrogen is a sustainable alternative to fossil fuels, but liquefying it for transport is costly and energy-intensive. The solution developed by IIASA researchers involves using solid air (either nitrogen or oxygen) as a medium for recycling cooling energy across the hydrogen liquefaction supply chain.
This process, known as Solid Air Hydrogen Liquefaction (SAHL), involves solidifying air to store the cooling energy from regasifying hydrogen, then transporting the solid air back to where the hydrogen was liquefied. By using the solid air to reduce the energy consumption for liquefying hydrogen, SAHL can significantly lower the cost and energy consumption of transporting hydrogen between continents. In addition, SAHL generates extra oxygen, which could be used for power generation with oxy-combustion and for carbon capture, use, and storage.
The authors of the paper believe that SAHL could increase the viability of a global hydrogen economy and diversify the number of hydrogen suppliers for energy-demanding regions like China, Europe, and Japan. The energy saved by using SAHL could also contribute to expanding solar and wind power in developing countries, boosting their economies.
The paper also addresses the ongoing debate in industry and academia about the best way to transport hydrogen by sea. Compared to other options like ammonia or methanol, liquefied hydrogen is the most efficient and cost-effective option, and SAHL could further reduce the energy consumption for hydrogen liquefaction by 25 to 50%.
Overall, the use of solid air as a medium for recycling cooling energy in the hydrogen liquefaction supply chain has significant potential to accelerate the transition to a sustainable hydrogen economy and mitigate climate change.