The Cleanest Train Ever Built

Monday, November 26th, 2007

Years ago, I assumed that Diesel locomotives were just like Diesel trucks, only larger and on rails. Then I learned that they were in fact Diesel-electrics:

In a Diesel-electric locomotive the Diesel engine prime mover drives an electric generator whose output provides power to the traction motors. There is no mechanical connection between the prime mover and the driving wheels (drivers). Conceptually, this type of locomotive is an electric locomotive that incorporates its own generating station, making it well suited for operation in areas that do not have electrified railways.

If you already have a Diesel-electric, it seems pretty straightforward to add a battery, which GE just did.

GE’s new hybrid train is arguably the cleanest train ever built:

GE’s hybrid locomotive cuts both emissions and fuel consumption by up to half by capturing the 207-ton train’s braking energy and using it to supplement the diesel engines to accelerate or climb steep inclines. No modern battery can capture, store, and redeliver that much power, so GE created its own: a 1,000-pound molten-salt cell, which combines sodium with a metal chloride. That chemical recipe allows more current to flow through it than other batteries, so the 20-cell system can deploy 2,000 horsepower in less than a second. The Evolution made its cross-country debut in May and carries its first commercial load in 2010. ge.ecomagination.com

Of course, the efficiency gains are greatest when the train needs to start and stop. This makes such hybrid locomotives ideal as shunting or switching vehicles, the tug boats of the locomotive world.

GM’s promised Chevy Volt, by the way, is this kind of hybrid — although it uses a gasoline engine, not a Diesel, to power its generator — which is not quite the same thing as a Prius-style hybrid. GM calls the Volt an E-REV:

Calling a car a hybrid signifies that it’s driveshaft can be turned both by an electric motor and a combustion engine. A plug-in hybrid is a car that has extended electrical capacity supplied from the grid allowing for extended driving in all-electric mode. Modified Priuses and the upcoming Plug-in Saturn VUE are examples of those.

EVs and BEVs are cars that only have an electric motor and a rechargeable battery. They usually have overall limited ranges. The Tesla and EV-1 are examples.

GM toyed with different terms to describe the Volt. They have decided on the term E-REV (with the dash, pronounced ee-rehv), which stands for extended-range electric vehicle. They like the marketing opportunities of “REV” (i.e. E-REVolution)

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