High temperature superconductors for power applications

High temperature superconductivity (HTS, discovered in 1986) remains an active area of research worldwide, because its higher Tc and, thus, more economical cryogenic cooling have raised the prospects for electric power application. The discovery of MgB2 has rekindled the search for new superconductors with higher Tc. Recently, various acceleration programs have been launched in Europe, USA and Japan. The advance in HTS conductor has enabled the demonstration of various application prototypes, including, power cables, transformers, motors, and fault current limiters. However, full commercialisation of HTS application critically relies on the realisation of HTS conductors that are reliable, robust and low cost with low AC-losses. Worldwide activities are, therefore, focused on developing processing technologies to fabricate the so-called coated conductor based on YBCO to fulfil the stringent specifications. While a high critical current density of around 5 MA/cm2 (77 K) has been achieved, the conductor cost is currently estimated to be 10–50 times higher than what would be accepted.