An assessment of self-(Cold-) supported SMES systems

Abstract

The perceived long-range application of Superconducting Magnetic Energy Storage (SMES) has been for large-scale applications. Since SMES is highly efficient and has a rapid response time, it has a significant technical advantage over other storage technologies. Though the cost per 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 electromagnetic force is directly proportional to the stored energy. Recognition of this fact led to the proposal of warm- or external-supported 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 cold- or self-supported SMES design to determine if it has sufficient material 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 reviewed.