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Method | Description | Advantages | Disadvantages | Status |
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Shipping: ammonia | By combining hydrogen with nitrogen to create ammonia (NH3) and then liquifying (-33oC), density can be significantly increased | High density means low cost to ship. If ammonia can be used directly, conversion losses are only 7–18%. Some transmission infrastructure already established | Round trip conversion losses if a pure form of hydrogen is required (such as for fuel cell vehicles) are 14–36%. Toxic | Potentially suitable, particularly over longer distances and where re-conversion is not needed. |
Shipping: other LOHCs | Hydrogen density can be significantly increased by combining with a ‘carrier’ molecule such as toluene | Can be transported as liquids without any cooling and therefore very low shipping costs. Could use adapted existing oil tankers | High conversion losses currently (35–40%). Potentially toxic. Multiple solutions still being trialled | Potentially suitable but technology still in its early stages |
Shipping: liquid hydrogen | Hydrogen liquifies at -253oC, increasing its density by 800 times | Liquefaction significantly reduces transport costs/unit. Could use a similar technology to existing LNG vessels. Delivers pure hydrogen | Liquefaction and maintaining a low temperature consume significant amounts of energy (25–35%) & a certain proportion is lost as boil-off | Potentially suitable but highly capital intensive. First liquid hydrogen ships expected in 2022 |
Shipping: compressed hydrogen | Compressing hydrogen to 250 bar significantly increases the volume of hydrogen that can be stored | No conversion losses and only modest technical challenges to store compressed hydrogen. Delivers pure hydrogen | Relatively high shipping costs per unit reduces cost efficiency with distance | Potentially suitable. Type approval in principle from the American Bureau of Shipping. Construction of pilot ship expected to begin shortly |