Global cost optimization of 1-10 MWh toroidal SMES

The toroidal superconducting magnetic energy storage (SMES) configuration has a much reduced stray field over a solenoidal SMES. This allows the entire SMES facility to be placed in a high density environment where both personnel and equipment can be located closer to the magnet. In the past, this concept has been resisted due to the increased magnet cost for a large toroid over a solenoid storing an equivalent amount of energy. Preliminary studies have indicated that when the entire system cost is considered, the penalty may not be so excessive in systems storing a few MWh as is the case for applications like transmission stability and spinning reserve. The author is developing a cost model for the toroidal SMES system which will assist in selecting the optimum architecture, shape, and aspect ratio for toroidal coil modules which can be used for systems storing from 1 to 20 MWh. The global optimization model includes detailed magnetic, structural, and thermal considerations and provides cost analysis for all aspects of construction. Construction and material costs are based on cost estimating relationships and firm estimates derived from construction of a number of large industrial magnets and other equivalent systems at both Lockheed Martin (formerly General Dynamics) and Bechtel.