Do it faster, do it cheaper and do it greener than before.
Transit authorities face these increasing pressures every day, charged with supporting local and regional economic growth by moving human capital more efficiently than other metropolitan areas. Rail transporation is benefitting from a series of new technologies that save energy, reduce maintenance costs and improve the passenger experience.
Catenary-free operation (CFO) is driven by the desire to improve aesthetics. Wires and supports blemish the view of historic or architecturally pleasing urban locations, and municipalities and transit authorities would love to eliminate them as much as possible. Introduced about four years ago in Europe, CFO is gaining traction here as technology improves.
Catenary-free gains ground in North America
Henry Wesling, in the business development department of Bombardier Transportation’s propulsion group, said battery power is the most popular CFO method. The company last fall contracted with Saft to provide batteries for 26 five-car EMU train sets for use in the south of England.
Batteries are typically charged in a wayside overnight, then use regenerative braking technology to recharge during runs. Additional charging stations can be set up at stations with a single, unobstrustive catenary for quick refreshers along the way. Wesling said batteries can power a train for 2-3 miles before recharging is necessary.
There isn’t a maintenance cost associated with a battery, Wesling said, but they are expensive to replace and their shelf life depends greatly on the care they’re given. Optimizing cooling and heating cycles, and charging/discharging cycles, can allow a battery to last up to eight years. And by then, advances in battery technology are likely to reduce their size — they usually sit on the roof of a car — and provide even greater efficiency.
The Southest Pennsylvania Transit Authority — SEPTA — does not have CFO for its eight light rail/trolley routs or its 13 regional rail lines, and has no plans to go wireless at any time in the near future. But the organization is combining a series of advanced technologies to not only save and store energy, but generate revenue.
The process starts with regenerative braking, capturing the heat energy produced when the trains slow and stop. But instead of simply using that power to feed the train or nearby trains, SEPTA eyed a larger opportunity.
Using a 400 megawatt battery from Saft and a controller produced by ABB Envitech stored together at a wayside, SEPTA captures the regenerative braking power for two purposes. First, it helps power the wayside and cuts energy costs. Andy Gillespie, SEPTA’s chief engineer, said the substation uses 12-13 percent less electricity than before.
SEPTA also uses the stored energy for frequency regulation, essentially selling power on an as-needed basis to PJM Interconnect, which coordinates the movement of power in 13 states on the East Coast. PJM needs to keep its power grid balanced between supply and demand, a process made more challenging by the use of alternative — and wildly variable — sources such as wind and solar power. The energy from SEPTA’s wayside energy storage is more reliable than alternative energy and quicker to access than traditional forms. Hence, it’s something PJM will pay for.
According to a blog on its website, SEPTA anticipates generating as much as $250,000 a year from frequency regulation and other demand response programs.
Gillespie said SEPTA hopes to install a second battery by the end of 2014, and eventually have 10-15 units installed across the network.
Supercapacitors gain traction
A similar project was installed in Portland this October, using a supercapacitor, instead of batteries, to store and then use regenerative braking power. Siemens’ Sitras SES storage unit will not actually be functional until 2015, when the TriMet system’s new Portland-Milwaukie line opens. The TriMet system has long used regenerative braking power, but now this power will be stored to maintain a constant voltage across the entire network, which expands to 60 miles when the new line opens.