A new Japanese national project has started in 2008 to develop high temperature superconducting electric power devices. In this project, we have developed a superconducting magnetic energy storage (SMES) system, which are highly expected as a stable power supply. Main issues are a large current capacity conductor made of YBCO-coated tapes and a compact coil wound the conductors. Aiming at the manufacturing of compact coil with higher energy density through the creation of higher magnetic field, we produced YBCO coil, and by carrying out hoop stress tests. Also, aiming at the development of 20 MJ class SMES component coils necessary for picturing the technological outlook of 2 GJ class SMES coil for power system control, we manufactured component coils (outer diameter 650 mm), adopting the bundled conductor that would enable the realization of high strength and low loss, proving that its current capacity was large enough to exceed 2.6 kA, through basic verification test for energization. In addition, we have challenged the development of high efficiency coil conduction cooling technology, stable manufacturing technology of coated conductors for SMES and the highly reliable/highly durable SMES coil component technology.
