If you are going to use batteries, why bother to boil water and make steam? Why not just use the electricity to power motors? And don't forget that the carbon footprint includes the generation of the electricity used to charge the batteries unless non-carbon based energy is used.

Mark,

I highly encourage you to the narrow the scope of the project to something more manageable. A scale stationary air-powered engine is a good collegiate design project.

As for full size, a steam locomotive w/ tender full of batteries would likely run out of juice on "fire-up" before leaving the enginehouse. The energy density of combustion is about 10,000x that of batteries.

Mark, I just looked at this thread, and I have to parallel Ron Travis: Why? Why did your friend pick this as a senior engineering project in school?

Even with using external power to "fire up," your current drain when on battery power will be enormous. Overall efficiency is going to be terrible because of the nature of steam engines; most didn't even get out of single-digit ranges for thermal efficiency. Their saving graces that lead them to last as long as they did were relatively cheap purchase costs, the ability to run on the cheapest of fuels, and their simplicity and robustness. Once diesels got the reliability and power levels up, steam died.

Perhaps the proper question is, what is he trying to do? Is he trying to come up with motive power that's truly "green?" More likely, is he trying to come up with "green" power that's also "fun?" (Hey, why do you think we are here, and why do most of us have an interest in steam?)

If the answer is "green" railroading, then straight electric will be the best way to go. His main challenge will be to come up with either a battery locomotive, or a cheaper way to electrify a railroad. If he is of the opinion that electrification is out for capital cost reasons (and there is a lot of mileage that might be questionable for that), then he could be looking at another "green" form of power with a smaller carbon footprint.

W. H. Odom (who goes by whodom for his user name, and who moderates the Ultimate Steam page) suggested a while back that modern, wood-fired steam would be or could be carbon-neutral, by virtue of using what I would call "new" carbon from freshly-cut trees, instead of "old" carbon that accumulated from way back when coal and oil deposits were formed. There was even a railroad in Africa--I'm afraid I've forgotten which country and carrier it was--that ran with wood-burning steam power into the 1960s or 1970s. This road used fast-growing eucalliptis trees in groves planted for just this purpose.

Alternately, if he is looking for something with zero emissions that can also be "green," and isn't electric, there is the fireless locomotive, essentially a thermos bottle on wheels. This was an engine charged with hot water and steam from a stationary or "house" boiler, and relied on the principle that water that is above normal boiling temperature will not turn into steam until some of the pressure is relieved. Quite a few such locomotives were built over the years for industrial service in places where steam was available; they were considered the best thing for working in a potentially explosive atmosphere, such as the area around a chemical plant or an oil refinery. These machines could and often did have long lives, due to the low maintenance demands of a simple pressure vessel, rather than the much more heavily strained, more complex, and thus more maintenance intensive boiler.

http://en.wikipedia.org/wiki/Fireless_locomotive

http://www.internationalsteam.co.uk/tra ... dern21.htm

http://www.northeast.railfan.net/steam21.html

Somewhere in my magazine collection is a copy of an article from the 1940s about a proposal--pie in the sky stuff, really, just exploring the idea--of expanding the fireless locomotive to mainline sizes. Among other things, it wouldn't need a tender, but to carry enough steam and water for the power output of a 4-8-4, the machine would have to be of enormous size, particularly in length. I suspect axle loads would have been rather heavy, too.

Anyway, tell your friend to have a bit of fun.

Mark,

Going back to your initial proposal, I am wondering what the purpose of this electrical steam locomotive would be. Is it to provide a new type of locomotive for commercial application to pulling trains; or is it to create a lower emissions type of steam locomotive to appeal to those who like steam locomotives per se?