Help!!! What is a diesel-electric's fuel efficiency?

Trains.com General Discussion (Trains.com)
1

I know the fuel efficiency of a diesel engine – it varies from 40-50%, depending on a number of factors.

I’m looking for the efficiency of the locomotives generator/controller/motor combination. If we have 90% efficient generators and motors, it would seem that the combination would only be about 80% efficient.

However, I’ve heard that the latest locomotives have their electric efficiency up above 90%.

Does anyone know if this is true or not, and is there someplace on the web that discusses this?

Thanks!!

2

Railroad Doc,

No, the best you could expect would be 90% FOR EACH CONVERSION.

So an AC Locomotive like an SD70 MAC would have 90% in the generator, 90% in the DC to AC conversion, and 90% in the motors.

For the diesel engine itself I prefer to think in terms of 0.2 kg/kW hour, which gives you a cost of fuel in dollars! And that is at maximum efficiency!

Peter

3

Nah, you can do better than 90% – at least for electric motors.

Apparently 95% efficient electric motors are available:

http://www.eere.energy.gov/femp/technologies/eep_emotors.cfm

I would suspect that if 95% efficient electric motors are available, than 95% efficient generators are also available. And that seems to be the case. . . .

http://www.llnl.gov/str/Hybrid.html

As far as power conversion efficincies, how about the high 90s?

http://www.electronicproducts.com/ShowPage.asp?SECTION=3700&PRIMID=&FileName=POWER-ONE.aug2004.HTML

Granted the last reference was more for computer type applications, but it’s still pretty good.

So the question still is. . .what electrical efficiencies does the modern diesel-electric locomotive boast?