Stationary applications of energy storage technologies for transit systems

Stationary energy storage technologies can improve the efficiency of transit systems. In this paper, three different demonstrations of energy storage technologies for transit systems were reviewed and discussed. The demonstrations reviewed were a sodium sulphide battery system in Long Island, a flywheel system for the London Underground, and a capacitor system for Madrid de Metro. Analysis was conducted from the point of view of a transit agency evaluating these demonstrations for practical lessons learned, effectiveness of the installation, and return on investment. Each installation showed that their technology was successful in their task and also provided valuable lessons on the challenges of implementing new technologies. Information from independent sources about longer demonstrations would be particularly valuable to help accelerate acceptance of energy storage technologies for transit systems.