Design of a Submarine 30-km $\text{MgB}_{2}$ Cable for the Combined Transfer of 0.3 $\text{GW}_\text{e}$ and $\text{LH}_{2}$ from Offshore Plants to the Ravenna Port

A submarine, hybrid cable for the simultaneous transfer of green electricity and Liquid Hydrogen ($\text{LH}_{2}$) in a 30 km-long pipeline from an offshore renewable power plant, in the Adriatic Sea is presented here. The superconducting (SC) cable is designed with $\text{MgB}_{2}$ strands to carry the transport current with a significant margin. The SC strands are twisted around a bundle of normal conducting strands with the function of protecting against overcurrents and ensuring at the same time flexibility of the cable. The SC cable, covered by multiple layers of cold dielectric, is inserted into a corrugated pipe, constituting the inner part of a cryostat where $\text{LH}_{2}$ flows. $\text{LH}_{2}$ has the dual function of cryogen and energy carrier. The outer part of the cryostat is designed to limit the heat load to less than 2 W/m, and to withstand the pressure in operation due to the submarine installation at a maximum depth of ∼ 50 m.