Along this same line, I've read several references to combined cycle
locomotives in the various papers on alternative fuel locomotives
which were proposed in the 1980's.

I read someplace (ACE papers probably) that authorities felt at that
time that the only way to significantly increase the thermal
efficiency of the basic diesel-electric locomotive was to
add "Rankine bottoming". This undoubtedly means to add a boiler
which could extract waste heat from the diesel engine's relatively
hot exhaust, then use this steam to power a supplemental turbine
(probably powering a generator) to extract additional usable energy
from the diesel fuel.

ACE pointed out that the cost and maintenance of such a locomotive
would likely be worse than their proposed (complicated) ACE 3000 coal-
burning steamer, which would make the ACE option better from a life-
cycle cost standpoint. I don't know if any diesel-electrics with
Rankine bottoming were seriously proposed or not.

I am sure it is at least technically possible to build a combined
cycle gas-turbine electric locomotive, but this would add immensely
to the complexity of the locomotive, especially for controls and
maintenance.

The Union Pacific Railway built several gas-turbine electric
locomotives in the 1960's, but none was considered completely
successful. The main problem, as with all turbine powerplants, is
that the efficiency was miserable at anything less than full load. I
would be very curious to know if the 40-50% thermally efficient
natural gas fired gas turbines mentioned in this article considers
part-load efficiency. 40-50% sounds really good but I imagine this
will drop drastically in a typical locomotive application which
spends much of the time at part throttle.

Good Steaming,
Hugh Odom

--- In steam_tech@y..., "s-teamman" <s-teamman@x> wrote:
> Sounded very credible , UNTIL, they put the turbine into the
firebox. Maybe
> I am still too sane to see the vision ?
>
> By the way, any thoughts on my 40% cut off idea. ?
>
> Keep steaming,
> Steamman.
>
> >
> > There seems to be some modern opportunity to re-introduce the
combined
> > cycle
> > locomotive (gas turbine plus steam) to modern service. As you may
be
> > aware,
> > there is a new gas-turbine project underway with the Railpower
group <A
> > HREF="http://www.railpower.com/">
> > http://www.railpower. com</A>