They sit on a spur of test track outside General Electric’s locomotive factory in Erie, Pennsylvania, panting and grumbling like two old lions half asleep. The ominous, muttering rumble is the sound of 8,800 horsepower at idle—24 cylinders with pistons big as buckets, turbochargers the size of washing machines, two V12 engines direct-driving alternators five feet in diameter. These are two of the most advanced diesel-electric locomotives in the world: GE Evolutions, running all-new powerplants designed specifically to meet stiff Tier II EPA locomotive emissions regulations that go into effect next year.
You didn’t know locomotives had emissions regs? Neither did I. I assumed that the 207-ton iron gorilla of the wheeled world damn well did whatever it wished. But the new Tier II standards require substantial cuts in NOx and particulate matter, and GE, one of the world’s major locomotive manufacturers, has designed a new engine to meet them handily. The engine has an air-to-air turbocharger intercooler that lowers induction-air temperature to only a few degrees above ambient, for cleaner emissions and more power. Not only is the new GEVO 12 four-stroke diesel 40 percent cleaner than its predecessor, it’s three percent more fuel-efficient as well.
That may not sound like much, but it’s huge: A half-percent improvement is a big competitive advantage in loco sales. A locomotive typically burns about 300,000 gallons of fuel a year, and saving 9,000 gallons per engine can make a big bottom-line difference.
A modern locomotive is a hybrid. The diesel doesn’t drive the train; it cranks an alternator, which powers the six huge electric traction motors that actually turn the locomotive’s wheels. Each motor is set transversely between a pair of drive wheels. On an Evolution the electric motors will put out a total of almost 60,000 pound-feet of torque at start-up—the equivalent of about 120 Ferrari Enzos—good for a zero-to-60 time, unloaded, of just shy of 45 seconds. Rather longer, though, if you’re dragging a 17,000-trailing-ton coal train.
The traction motors also brake the train. When the driver (“engineer” no longer being the term) wants to slow down, he turns the motors into generators, reversing the field so they’re making electricity rather than consuming it, and are thereby magnetically resisting the turning of the wheels. This is a lot cheaper than replacing brake shoes, which won’t last long if asked to hold back a train that is as heavy as a tramp freighter. The wheel brakes are used only at slow speeds and to bring the train to a complete stop.
The excess current produced is dissipated by a series of big, fan-cooled “dynamic-brake grids,” effectively the world’s largest hair dryer, near the top of the car body, toward the back. Does the grid actually glow, I ask lead systems engineer Mike Schell? “It does when it catches fire,” he says with a straight face. But even with the blowers at work, you wouldn’t be able to tolerate the compartment where the grid lives.