BACKGROUND
Rail transit is experiencing increased ridership as a byproduct of the recent rise in price of gasoline that is further taxing the nation’s rail systems. At the same time, the price of electricity that powers rail transit systems is rising because of the nationwide rapid growth in electrical demand and the limited capacity of a strained electrical grid. Further, existing rail power substations may be inadequately equipped to support running heavier trains with more passengers; operating higher performance trains; and operating more frequent trains on shorter headways.
There is a way out of this dilemma for rail transit systems in the form of trackside energy storage systems, which would recycle regenerated energy from braking, reduce voltage sag between existing substations, and reduce peak power demands thereby reducing electric utility costs. Trackside energy storage units in the form of advanced batteries, electrochemical capacitors and flywheels have come a long way in recent years and some of which have been successfully applied in Europe and Japan.
Energy storage in general, other than a few scattered past trials, is very new to US transit agencies. The average transit agency is overwhelmed by the need to amass knowledge on new storage technology quickly, and to learn how to efficiently perform engineering analyses needed to define the design and operation of energy storage technologies. They also need to understand the current state of energy storage technology, the role of utilities as potential partners, and the expected direction of new research and its affect on transit operations.
SUMMARY
Since the issue of energy efficiency involves both rail transit and their electric power suppliers, APTA has teamed up with the Electric Power Research Institute (EPRI). EPRI represents power utilities, together producing and distributing 90% of the electric power used in the US. From this initial partnership, an APTA trackside energy storage consortium formed this year to bring awareness to this topic. The consortium consists of major transit agencies from Los Angeles, Washington DC, and New York, plus the New York Power Authority, and government energy storage funding administrators like Sandia National Laboratory. The consortium has held two web broadcasts, plus its first on-site planning meeting at WMATA with further meetings planned for Los Angeles.
The consortium has performed a needs assessment of rail transit agencies from which it was determined that a technology awareness study is needed to help agencies utilize energy saving technologies such as wayside energy storage devices. The study would address the engineering analyses needed for selecting and sizing energy storage technologies including a discussion of the problems storage could solve, plus detailed computer simulation methods needed to assess performance and rate of return calculations, and how agencies might benefit from their collaboration with electric utilities. Information for the guidebook would come from transit and vendor site visits; interviews with storage experts and experienced consultants; computer simulation studies; and engineering modeling and computational case study analyses. A research team, which includes transit agencies, energy storage experts, and mathematical simulation experts with facilitation and other engineering expertise from APTA and its members, has been performing the work and has submitted preliminary results.
Status: The draft final report has been completed and is available as a web-only document: Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities
