[factoryrat]

I work for a railroad, in a diesel locomotive repair and servicing shop.

I have yet to see an SCR equipped locomotive come through. They do exist, but they are few and far inbetween.

The answer for the railroads is to offset high NOx producers with “credits” from low NOx producers.

Anyway, our main concern is with particulate emissions, which is a sign of poor efficiency, not to mention setting wayside fires by blowing sparks of burning carbon out of the stack.

Thermal efficiency of a diesel engine is diametrically opposed to NOx emissions. Diesels need high compression and combustion temps to wring as much power out a pound of fuel as possible.

[RayChuang88]

BNSF just in the last few months took delivery of the first EPA Tier 4 certified diesel-electric locomotives from GE Transportation Systems (I believe they are the newest Evolution ES44DC models assembled at a recently-opened plant near Fort Worth, TX). They're so new I don't think they've left Texas yet, the last I heard.

They have quite different-looking cooling radiators from previous Evolution ES44DC locomotives from the pictures I've seen. And they are supposed to have the very latest emission control systems (certainly a state-of-the-art DPF).