LIQHYSMES—size, loss and cost considerations for the SMES—a conceptual analysis

A new energy storage concept for variable renewable energy, LIQHYSMES, has been proposed which combines the use of liquid hydrogen (LH2) with superconducting magnetic energy storage (SMES). LH2 with its high volumetric energy density and, compared with compressed hydrogen, increased operational safety is the prime energy carrier for large scale stationary energy storage. But balancing load or supply fluctuations with hydrogen alone is unrealistic due to the response times of the flow control. To operate the hydrogen part more steadily, additional short-term electrical energy storage is needed. For this purpose a SMES based on coated conductors or magnesium diboride MgB2 operated in the LH2 bath, is proposed. Different solenoidal and toroidal SMES designs for the 10 GJ range are compared in terms of size and ramping losses. Cost targets for different power levels and supply periods are addressed, taking into account current developments in competing short-term storage devices like super-capacitors, batteries and flywheels.