The Cost Savings of Steam Today.

[NW Mailing List]

"Simple questions" from a layman-lawyer neither an engineer nor a physicist  
(and questions that are, I suppose, very elementary from a professional  
engineer's standpoint):
 
What are the cost factors of running steam vs. running diesels aside  from 
the inherent cost-efficiency of the diesel engine itself vs the  efficiency (or 
lack thereof) of the steam engine itself? That is to say, what  non-engine 
indirect factors enter into the equation, such as maintenance of  
coaling/watering facilities, labor costs, and other factors/facilities  related to steam 
operations that are absent from diesel operations?
 
In a long passenger run - say the Powhatan Arrow - from Norfolk to  
Cincinnati, was it necessary for the J and its tender to be serviced (coaled and  
watered, lubricated, etc.) at one or more points along the run? And was more  than 
one J used for the run, or did just one J suffice?
 
When a diesel engine powered the Arrow did it require  stops for servicing 
along the way? 
 
Assuming that the Arrow had been a true "express" non-stop  train running 
from Norfolk to Cincinnati, and assuming further that either one  steam engine or 
one diesel engine was able to make the run without even one  servicing stop, 
which engine would prove out to be the more "efficient" of the  two, given 
today's oil-vs-coal costs? 
 

>From a beady-eyed cost-accountant's standpoint, is there any real way to  

bring cost-efficiency standards for a modern steam engine up to those of  the 
modern diesel, all operational elements being considered?
 
In short, is a "return to steam" merely a  pipe-dream?
 
John Carnahan
Columbus
 
 
 
In a message dated 1/14/2008 5:38:11 P.M. Eastern Standard Time,  
nw-mailing-list at nwhs.org writes:

 
John:    
Yes,  And yes,  that is what I said.  The diesel engine will always be more 
thermally  efficient, but it is the total system efficiency that is the 
important  value.  Also, the life cycle cost- development, implementation plus  
continuing maintenance/ up-keep and operating costs- is the value that must be  
worked with. 
The hassle is that in  introducing new technology the above factors don’t 
have known and reliable  values.  Thus, getting a company or society to adopt the 
new technology  is difficult as the risk cannot be accurately assessed and 
the true future  cost determined.  Societies and companies are almost always  
conservative. 
Gary  Rolih 
Cincinnati   
 
 


 
  
____________________________________
 
From:  nw-mailing-list-bounces at nwhs.org 
[mailto:nw-mailing-list-bounces at nwhs.org]  On Behalf Of NW Mailing List
Sent: Saturday, January 12, 2008 10:37  AM
To: NW Mailing List
Subject: Re: The Cost Savings of Steam  Today.
Gary,

Have  you read the paper?  With the massive cost difference between Coal and  
Diesel fuel, the steam locomotive can have lower thermal efficiency and still 
 be cheaper.  The number I quoted in the email i originally sent was based  
on steam locomotives having about 10% thermal efficiency compared to diesels  
running at 25-30% thermal efficiency depending on type.  Steam  locomotives in 
service in other countries have exceeded the thermal efficiency  I used for 
the locomotives in my comparison. 

John  Rhodes. 
 
On Jan 11, 2008 6:26 PM, NW  Mailing List <_nw-mailing-list at nwhs.org_ 
(mailto:nw-mailing-list at nwhs.org) >  wrote: 
 
 
 
 
Guys:  No matter what, physics  still dictate the overall thermal efficiency 
of the diesel cycle and thee  steam locomotive cycle.  The thermal efficiency 
is a function of the  temperature difference achieved when expanding the gas 
in a cylinder from te  beginning of the cycle to the end.  In this case, 
burning inside the gas  to be expanded in the cylinder (diesel and about 5000F) and 
burning outside  the gas to be expanded (steam locomotive and a steam inlet 
temperature  of about 800F after transferring to steam in a boiler) gives the  
advantage to the diesel for thermal efficiency FOREVER.   
The conversion efficiency of each type  ultimately matters: i. e. steam 
requires burning coal which burns at a high  temeperture (roughly 4000F), heat gets 
transferred to water in the boiler with  a lot of losses, losses in heat and 
pressure in flowing the steam through the  piping, parasitic losses when 
taping steam off to run electrical turbines,  feed water heaters and so on.  
Diesels have similar conversion  issues. 
Turbines can be very efficient, but the  meaning of this is that the flow of 
gas through the turbine blading AT  DESIGN CONDITIONS can transfer most of the 
energy in the gas ( heat energy,  kinetic energy and pressure energy) to the 
blades as mechanical work very,  very well.  However, "part throttle" 
operation means that the flow is not  at the design conditions ( the vectors of the 
flow of the gas are not at the  optimum direction) and the transfer of energy is 
much, much less  efficient.   ( think of the turbine blades as little wings 
that are  forced to take different angles of attack from the on-coming gas 
flow; at part  throttle, little wings don't work very well at all at the wrong 
flow angle-  they can stall!)  Turbine can be as much as 98-99% efficient with 
repect  to capturing the energy in the flow.  Off design, the efficiency can 
drop  significantly to levels as low as 30%.  But what about the rest of the  
system needed to make steam for the turbine?  How efficient is  that?   
Could steam be used today again in a  profitable and efficient way?   
Probably not, the conversion cycle  is not very efficient and the opportunities to 
make improvements in it are not  good ones. 
Coal fired turbines?  Tried for  years, but burning raw coal in the gas 
stream has always caused serious slag  issues in the combustors.  The slag either 
erodes away turbine blades or  coats the blades and ruins the wing shape.  This 
is a virtually  intractable problem.  The coal needs to be refined to get rid 
of the slag  products--- which leads one right back to refining petroleum to 
make diesel  fuel or converting coal to an oil in another refining type cycle 
(the Nazis  did it but it is an expensive and inefficient process).  And 
turbines  lead right back to the off-design issues at part throttle.    
While a cycle or an energy conversion  process can be proposed, the devil IS 
in the details.  Developing a  process to work reliably, economically and 
environmentally acceptably take a  whole bunch of time and money.  Then you have 
to get the entire world to  adopt this way of doing business. 
Ed and Harry are right to voice  skepticism at this early stage.  Adopting 
new technology and getting it  into place is a very, very difficult process.  
The internet was invented  in about 1970- 37 years ago- and only part of the 
human race has access to  this today. 
Gary Rolih    
Cincinnati 





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