Long distance renewable-energy-sources power transmission using hydrogen-cooled MgB2 superconducting line

Renewable Energy Sources (RES) exploitation for electric energy and hydrogen production has been identified as one of the leading ways towards a future sustainable energy system. Hydrogen can be stored and transported in gaseous (GH₂) or liquid form (LH₂). When large hydrogen storage is required, liquefaction can be convenient with respect to compression, because of its higher storage density. LH₂ can also be used as a coolant for superconducting lines, acting at the same time as energy vector and cryogen. In particular, in this paper we focus on the MgB₂ material mainly due to economic considerations and working temperature match with LH₂. A system for large scale RES exploitation allowing flexible and controlled delivery of electric energy and LH₂ is presented. For the thermo-hydraulic design, a method is proposed which resorts to compressible fluid equations put in a convenient simplified form. A case application with 20 km distance between cooling stations is considered, and the need of taking into account LH₂ compressibility for pipeline design is shown.