New York's Metropolitan Transit Authority has unveiled preliminary plans for a wide range of cleantech initiatives in its system, including solar and wind power, green roofs, water management, and some regenerative braking magic.

The largest public transit provider in the western hemisphere, the authority is responsible for running New York City's subways and buses, as well as two commuter rail systems, the Long Island Bus system, and seven bridges and two tunnels.

"Our average peak demand for power on any given day is about 600 megawatts," Peter Bass, director of environmental and energy policy at the MTA, told Cleantech.com.

And that's just in the city, which makes up the lion's share of the authority's power demand, said Bass.

The MTA has big plans for energy efficiency across the board, and making the subway cars more efficient could mean major savings.

"You make them a little bit lighter, you get a tremendous energy bang for your buck," said Bass. "We're looking at it in terms of both design for the next generation of cars, and retrofits, if you will, to the existing fleet as we maintain it."

And while there is some use of regenerative braking in the system, the potential is there for much more. But first, the authority needs to have a uniform fleet, with all of the cars running off AC power.

The subway system is an amalgamation of three different train systems dating back from the early 1900s to the 1930s.

Take a look at a really old subway car here >>

"Sometimes the trains are DC powered, the older ones, and the newer ones are AC," said Bass. "The third rail power is DC, and when we run an AC train, there's an inverter that changes it from DC to AC."

Add in computer-based train control, which would allow the MTA to operate the trains in closer proximity to one another, and then the magic happens.

"If you are able to run the trains closer, that means you can actually start to capture braking energy that gets put into the third rail from one car that's stopping, into the next train that's accelerating," said Bass.

"But they have to be close. They have to be near one another."

Check out a new train here >>

He said they're doing some installations of computer-based train control on some of the subway lines now.

Running the trains closer together would also mean being able to run more trains and move more passengers.

The Commission on Sustainability that worked on the energy efficiency plan for the MTA recommended that the authority should increase ridership to the maximum extent possible in order to directly reduce vehicle miles and carbon emissions in the region.

A major part of the authority's new initiative is to get 7 percent of its total energy needs from solar, wind, and other renewable sources by 2015.

"That will be done through a combination of distributed generation in our own facilities, but mostly through buying renewable energy credits through some agreement with the New York Power Authority," said Bass.

The MTA gets about 80 percent of its power from the New York Power Authority, or NYPA.

The distributed generation includes a proposal for a power purchase agreement for 6 MW of solar power at MTA facilities, creating what the authority said would be the largest solar power project in the state.

The MTA is also looking at generating 14 percent of the power at its bus depot in Far Rockaway from wind turbines, and a substantial portion of the Roosevelt Island subway station is expected to be powered by tidal energy from Verdant Power's underwater turbines in the East River.

Verdant's demonstration-scale project is expected to generate 35 to 70 kilowatts (see Verdant deploys tidal power array in New York), although the company had to pull its initial turbines out of the water last year after they took some damage from the rougher-than-expected East River tides (see the Cleantech Avenger's Mishaps and murmurs.)

Other initiatives include vegetated green roofs at three facilities, as well as a white roof at the Long Island Rail Road's Hillside building, which would reflect the sun and stay cooler than a dark roof.

The MTA is also taking a close look at water, and plans to map groundwater sources in its tunnels and properties and identify industrial and beneficial uses.

The authority expects to reduce the amount of potable water used to wash its vehicles, potentially using harvested rainwater and recycled gray water for its regular operations. The MTA said it could also use water harvested from the subway system for cooling some of its transformers.

The costs and timelines for all of these projects is varied, and not yet determined in some cases.

"What might we save with reductions in car weight, and how much would it cost and what the payback would be? Too soon, too soon to tell," said Bass.

"We only know that the potential is there, so it's worth our examining. But we haven't gotten to the point where we can start figuring out what the savings might be."

The commission's final sustainability plan will be released in December.