Subway systems are essential for enabling urban density and economic development, but they are increasingly expensive to run and expand. As urban populations grow, transit authorities must grapple with how they can expand service while dealing with the increasing operating and capital costs from electricity use and other power infrastructure.
Energy prices are expected to rise, and this puts pressure on transit authorities to mitigate operating costs associated with purchasing electricity from the grid. On the flip side, as train frequency increases to meet expanding ridership demand, new electricity infrastructure will also be required, such as substations, and this power infrastructure can be prohibitively expensive to develop in downtown urban areas where real estate is at a premium.
Batteries are a possible solution to both problems: a way to manage operating and capital costs simultaneously. As some transit authorities, such as SEPTA and the MTA, are already demonstrating, batteries can be used to capture unused electricity and return it to the grid. This helps to lower the electric bill by decreasing overall energy consumption and provides a means to manage power usage around peak times when spot prices are at their highest. Batteries could also help limit capital costs associated with building new substations. Energy storage technology can smooth out the gaps and drops in a subway’s power system that come from increased train frequency by releasing power back to the third rail when needed. While some new substations will still be necessary, in many cases, gaps and drops in the power supply that limit frequency often occur intermittently and only under peak or contingency conditions. In these instances, building a large new substation is wasteful excess when a cheaper, denser, and more compact battery system could fulfill the same role.
The increasing price of electricity poses a present and future challenge to transit authorities. As battery use becomes increasingly mainstream, it is time that the transportation sector adopt the technology to better manage power usage and limit investments in large-scale energy infrastructure to the places where it is only truly necessary.