An assessment of superconductive energy storage for Canadian freight railways

A superconductive wayside energy storage system (SM WESS) is assessed for technical feasibility and economic viability. The system, which would be used to store the braking energy of loaded freight trains in order to `peak shave´ the subsequent power demand by an electrified railway is compared to a flywheel storage system. SM WESS implementation was considered for two iron-ore railways in Quebec, and the system specifications were taken to be 5.5 MWh (usable storage capacity) and 10 MW (charge peak power level). The technology of superconducting magnets is reviewed, and it is determined that the WESS magnet would be much larger than any yet built, but considerably smaller than magnets proposed for utility load levelling. After evaluating alternatives, a simple solenoid geometry and a 4.2K pool-boiling refrigeration system are selected. The conceptual designs of magnetic, cryogenic and electrical equipment were developed to provide credible cost estimates. The initial and annual costs were estimated to be $33.2 (±5) million and $270 thousand, respectively. While the superconductive system is technically feasible, the authors conclude that the magnitude of the initial cost is likely to preclude further development of the SM WESS concept.