AN ASSESSMENT OF SELF-(COLD-)-SUPPORTED SMES SYSTEMS

The perceived long-range application of Superconducting Magnetic Energ y Storage (SMES) has been for large-scale applications. Since SMES is highly efficient and has a rapid response time, it has a significant t echnical advantage over other storage technologies. Though the cost pe r unit of stored energy, $/kWh, for several major components, such as the superconductor and the cryostat, decrease as plant size increases, the amount of structural support that is required to withstand the el ectromagnetic force is directly proportional to the stored energy. Rec ognition of this fact led to the proposal of warm- or external-support ed SMES, which has been the primary technology researched for the past 20 years. Recently, a team led by Bechtel suggested that cold or self support would be cost effective for SMES plants of intermediate size, i.e., from a few to several hundred MWh. This paper evaluates the col d- or self-supported SMES design to determine if it has sufficient mat erial to withstand the electromagnetic forces. The design is shown to meet a criterion derived from the virial equation. Earlier work, which predicted that larger quantities of material are required, is reviewe d.