New York's Metropolitan Transportation Authority (MTA) subways, buses and railroads move 2.4 billion New Yorkers a year — about one in every three users of mass transit in the United States and two-thirds of the nation's rail riders. Today this municipal authority runs one of the largest and most complex systems of its kind in the world, operating more than 2,000 track miles and serving, on average, approximately seven million passengers per weekday.

New York City Transit, the largest agency in the MTA regional transportation network, has ambitious plans to make its operations "green" and more environmentally friendly, in addition to efforts it has already undertaken to achieve sustainable, energy-saving results.

Energy-Saving Subway System
NYC Transit runs the largest fleet of subway cars in the world, over 365 days a year (excluding some days in December 2005). Here is how it saves electricity.

• The "new technology subway car" fleet has regenerative braking. This feeds energy into the third rail that would otherwise be lost as heat when the train stops.

• New York City Transit is currently replacing incandescent train signals with more-efficient light emitting diode (LED) signals.

• Throughout the subway system (including tunnels), fluorescent lamps are replacing incandescent lamps. As a result, station lighting has increased 750 percent, tunnel lighting has increased 500 percent, and NYC Transit saves $4.8 million per year.

• In 1996, NYC Transit began the Subway Car Shunting Program, one of its most successful energy conservation projects, whereby the acceleration rate of the 5,800-car subway fleet is modulated. NYC Transit saves 240 million kilowatt (kW) hours of electricity annually this way.

Clean-Fuel Buses
MTA New York City Transit has more buses than any other public agency in North America. And it has sought ways to make its bus fleet better for customers by introducing environmentally friendly features.

Since a plan was introduced in June 2000 to transform the NYC Transit bus fleet into the cleanest in the world, more than $300 million from the 2000-2004 Capital Program has resulted in the following:

• NYC Transit has the largest hybrid-electric bus fleet in North America. With more than 200 on order, the fleet should exceed 550 by the end of this year.

• In September 2000, NYC Transit became the first public transportation system in the country to switch all diesel buses in the fleet to ultra-low sulfur fuel, which has 90 percent less sulfur than traditional fuel and reduces emissions.

• To date, 642 buses have been re-powered with new technology diesel engines that are up to 94 percent cleaner burning. NYC Transit retired its last two-stroke diesel engines last summer.

• Approximately 2,700 diesel engines have been retrofitted with diesel particulate filters, an emissions control technology that reduces diesel particulate emissions from engines by as much as 95 percent. NYC Transit claims it will retrofit the remainder of the fleet by the end of this year. As well, 750 new buses have been delivered with diesel particulate filters.

• In 1999, Brooklyn's Jackie Gleason Depot converted to natural gas operations. The Bronx's West Farms depot, which reopened in 2003 after renovations, today also optimizes compressed natural gas (CNG) buses as half its fleet.

Green Building
NYC Transit Capital Program Management's Environmental Management System (EMS) incorporates Design for the Environment (DfE) that assures that all construction projects — from building design to subway expansion — consider ways to increase energy efficiency; enhance indoor environmental quality; conserve water and natural resources; and make beneficial use of waste.

Last year, NYC Transit unveiled a 100-kilowatt solar canopy at Brooklyn's recently reconstructed Coney Island-Stillwell Avenue station. The terminal, the first NYC Transit station to use solar energy, now has 60,000 feet of integrated photovoltaic (PV) paneled roof, which is expected to produce 210 kilowatts of solar power. Upon its completion of renovation on May 29, 2005, the Coney-Island-Stillwell Ave. station became the largest renewable-energy enabled mass transit station in the U.S.

Further, an expanded subway and bus maintenance facility in Corona, Queens, is being designed to use rainwater and recycle wash water in its subway car wash. When rainwater falls on the roof of the Corona maintenance building, drain lines will transport it to an underground trough. Additional pipes will carry recycled water to the car wash. (See how the car wash works by clicking here.) In addition to rain, sun also will be used in the Corona project, as a photovoltaic (solar cell) system will capture sunlight and generate electricity. Natural light replaces artificial light during the day. The building will also have natural ventilation to reduce the use of mechanical air circulation.

As well, according to MTA's Web site, the Corona facility will have a 200-kilowatt fuel cell system installed by the New York Power Authority (NYPA). Converting hydrogen and oxygen into heat and electricity will create power more efficiently and with less pollution. In fact, the facility is projected to exceed the state code for energy efficiency by 36 percent.

Scientific American editor David Biello, on the SciAm blog, last month recounted his recent tour of the MTA subway division's latest facility, "a 95,000 square foot railcar maintenance building nestled amidst the wetlands to the south of Shea Stadium." The large building, in Queens, has the responsibility of cleaning and caring for the 400 or so cars that travel between the borough and midtown Manhattan.

Inside the building — the external appearance of which is of bricks, mortar and cinderblock…hardly the appearance of being green — is "a 100-kilowatt array of solar photovoltaic cells harvests along the roof's southern exposure." And a 200-kilowatt natural gas-powered fuel cell, located on the northern side, is capable of supplementing or supplying the building's energy needs. These technologies both cut the facility's electric bills and its bad emissions.

According to Biello:

Combined they will avoid the emission of more than 500 tons of carbon dioxide, along with tons of smog-forming nitrogen oxides and acid rain-causing sulfur dioxide.

The facility's other green elements include special skylights to replace electric light during the day and a 40,000-gallon retention tank to capture rainwater for the washing process. A series of louvers enables the building not to need mechanical ventilation or air conditioning on the shop floor even during the most torrid summer days.

A downside, however, lies in that the MTA had to install 100 kilowatts of solar PV cells in order to average just 13.5 kilowatts of actual power annually, due to the intermittency of the sun. While the fuel cell provides the bulk of the load, according to SciAm, "the local utility requires a grid connection and diligently ensures that the authority can't send (and therefore sell) power back into its system (a process called net metering)." Although the fuel cell will pay for itself, it will take more than 23 years for the solar system to pay back its cost.

"If I was doing the building over again, there'd be no PV," Don Diego, the site manager, told Scientific American. "I'd put windmills on the four corners of the building. The payback on the PV system is terrible."

Still, Biello writes, the sun tends to shine exactly when demand for electricity peaks, allowing the MTA to harvest the savings of reducing their demand at exactly the right moment.

The MTA plans to get 20 percent of the energy required to run subways along its more than 800 miles of track from renewable resources such as the sun and wind. Already, it has several stations powered, at least in part, by the sun.

And more and more buses and trains in the system here in New York are employing greener processes. While much of the complex mass-transit system still requires Herculean efforts to reach NYC Transit's goal of an environment-friendly New York, at least the parks aren't the only things "green" anymore.

Resources

New York City Transit and the Environment
MTA NYC Transit

Greening New York's Subways
by David Biello
Scientific American blog, June 14, 2006