The public transport systems are always under pressure to cut costs and increase revenue. As an answer for this the Southeastern Pennsylvania Transportation Authority (SEPTA), which runs the transit system in Philadelphia, is piloting a smart electrical grid technology that could cut its electricity bills by up to 40 percent and generate millions of dollars a year.

The concept is simple but capital intensive to start with. A massive battery installed at one of the authority’s substations will store electricity generated by the braking systems on trains. The battery will help trains accelerate, cutting power consumption, and will also provide extra power that can be sold back to the regional power grid. To start with the pilot project will install such a battery at only one of the 38 substations in the transit system and is expected to bring in $500,000 annually. You can easily do the math and estimate the amount if all substations are made part of the project.

This project will not only generate revenue but save energy, avoid black outs and consolidate the renewable energy program. Several energy utilities are using this large battery technology. In this project it will be paired with software from a Philadelphia-based smart grid company called Viridity Energy.

via: technologyreview, worldchanging