The discovery of the superconductivity at a transition temperature (TC) of 39 K in magnesium diboride (MgB2) has attracted much attention from many researchers for scientific as well as technical reasons [1]. Compared with Cu-based superconductors (cuprates), MgB2 has lower anisotropy and larger coherence length, in addition to high Tc [2]. These characteristics of MgB2 give rise to new applications for superconductor devices that can operate in the temperature range between 20 and 30 K; examples of such devices are Josephson junctions and integrated circuits. This temperature range can be easily achieved by using economical and compact cryocoolers or liquid hydrogen. The use of cryocoolers may transform the superconductor from being specialized and advanced technology into common usage in consumer devices. In the future, hydrogen gas may be widely used for carbon-free power generation such as in fuel cells. Liquid hydrogen would be available for these purposes, and may be utilized for the cooling of low-temperature devices. In addition, MgB2 is considered to be a clean superconducting material, using neither toxic nor rare earth elements.