Amtrak is preparing to get greener. Moving a passenger by train is already more energy-efficient than doing so by car or plane, government statistics show: about 2,134 BTU’s per mile for an Amtrak train, versus 3,578 per mile for a passenger car at an average level of occupancy and 3,942 by plane for domestic trips, based on 2000 estimates.
The BTU’s in the car or a plane come from oil, while the ones in a train can come from a variety of domestic sources.
But Amtrak is announcing on Friday that it is ordering new locomotives that will use less electricity. Between 2013 and 2019 it will buy 70 new electric locomotives for use on the Northeast corridor between Washington and Boston and the Keystone Corridor between Philadelphia and Pittsburgh, replacing 64 locomotives, some of which date back to 1980 and have 3.5 million miles on the odometer.
The new trains, which are being built by Siemens AG based on a design it already sells in Europe, will cost a total of $466 million and have a variety of refinements. One important one is a feature called regenerative braking, which is common in cars like the Prius but not universal in electric locomotives.
Here is how it works: When a car or a train uses an electric motor to accelerate, the motor turns electric current into physical movement; when regenerative braking is used, the motor reverses its role. It acts as a brake and turns into a generator, converting movement back into electric current.
This works better in a train than in a car. In the car, the current goes back into the battery, which has limited capacity and can only accept it relatively slowly. On the train, the energy goes back into the overhead power lines and the electric grid, which can accept all of the energy quickly.
Jürgen Wilder, vice president and general manager of rolling stock at Siemens, explained that this allows trains to exchange energy. “Maybe another locomotive at the same time can be accelerated with the power that locomotive is going to give back,” he said.
Most of the engines to be replaced are AEM-7’s, known to rail buffs as “toasters” because of their boxy shape. Some do no regenerative braking and some can, but only at the behest of the engineer. Those engines are 7,000 horsepower and can draw about 5 megawatts for their motors, an amount that could run five Super Wal-Marts.
Amtrak’s express electric trains, the Acelas, already have regenerative braking.
The 70 new locomotives, which have a peak power of 10,000 horsepower and draw over 5 megawatts,will begin arriving in February 2013. They will replace 64 existing locomotives, giving the railroad somewhat more capacity for hauling passengers. Like the trains they replace, they will travel at up to 125 miles an hour on the Northeast corridor.
Siemens says the new locomotives will mostly be built in a factory in Sacramento, Calif., with 2 megawatts of solar cells on the roof.By MATTHEW L. WALD/NYT