Bulk power transmission at sea: Life cycle cost comparison of electricity and hydrogen as energy vectors

For the first time, a comparative economic study between hydrogen and electricity as energy vectors for bulk power transmission at sea was performed. The objective of this study is to seek the break-even distance for which the hydrogen transport alternatives become inexpensive than electricity under different electricity prices e.g., 20 USD/MWh (5.6 USD/GJ), 40 USD/MWh (11.1 USD/GJ) and 60 USD/MWh (16.7 USD/GJ). Four different scenarios were explored. The first two scenarios evaluated the power transmission of 2 GW between two shores separated by either shallow or deep waters. Whilst the remaining two scenarios analysed the power transmission of 600 MW between an offshore platform, close to an offshore wind farm, and its hinterland, in shallow and deep waters. For bulk power transmission of electricity, the use of a high voltage direct current through submarine cables was studied. In the case of hydrogen, two transport alternatives were evaluated: hydrogen transported through pipelines and by ships in liquefied and compressed states. The findings of this study indicate that for a 2 GW power transmission and distances slightly over 1000 km in deep waters, the hydrogen transported through pipelines is cheaper than electricity, even when the electricity prices are low. Overall, among the hydrogen transport alternatives, the best solution is to transport liquefied hydrogen by ship.