Demonstration of kA-Class Rutherford Cables Using MgB₂ Wires for an Energy Storage Device Suitable for a Liquid Hydrogen Indirect Cooling

Superconducting Magnetic Energy Storage (SMES) has been a promising option amongst potential other storage devices to support world-wide demands for introducing more renewables into the utility grid. If MgB2 strands are used for SMES, liquid hydrogen, one of the renewables, could be used not only as a clean energy source but also as a coolant for the superconducting device. For large-scale coil design, mechanically fragile multi-filament strands should be used for their low AC loss feature considering that the transport current inside the coil would be always changing. To realize such a design, we designed and fabricated the large current capacity for AC-use Rutherford cable, together with experimental tests for its feasibility assessment. Based on the latest test results and development of commercial MgB2 strands with high mechanical strength, and this research and development of kA-class cable at liquid helium temperature for extrapolating the critical current (I-c) at hydrogen temperature, we believe this approach has the potential to make a practical SMES device with MJ capacity. In this paper, the world's largest-capacity AC cable design and test results including critical current evaluation under several background field strengths are shown, and the stability and current re-distribution are also discussed.