Electrics, was Re: Steam (NW Mailing List)

[NW Mailing List]

NW Mailing List wrote:

> Exactly; if you want a coal-powered railway today, build a coal-fired 

> power plant with the requisite pollution-control equipment (which could 

> never be accommodated on a loco anyway) and hang some wire.


This brings up a fair point, and one which few steam locomotive fanatics 
(and I include myself in that group) are happy to admit.  A steam 
locomotive under heavy load can throw a LOT of stuff into the air.  Look 
at the firing rates of even the best locomotives, compared to stationary 
or even marine boilers.  Here's a paragraph from John H. White's "A 
History of the American Locomotive":

"To produce the desired performance within severe weight and size 
limitations, the locomotive boiler was of necessity worked very 
intensely.  In stationary, and to a lesser degree, in marine practice, 
boilers might be as large as required for optimum performance and 
efficiency.  Such boilers were worked "lazily" and were spread over a 
large area.  But locomotive boilers restricted by weight and clearance 
specifications were limited in size and were worked hard.  A reasonable 
rate of combustion might be set at 100 pounds of fuel per square foot. 
For the sake of economy, stationary boilers operated at only 15-25 
pounds per square foot.  Railway engines, because of the tremendous 
demand for steam and the limited size of their fireboxes, were forced to 
burn 200 pounds per square foot, a rate far in excess of what was 
considered reasonable.  This explains the poor efficiency, high 
maintenance cost, and short life of locomotive boilers."

I believe that these numbers refer to coal fired locomotives of about 
the turn of the century.  It would be interesting to see the total 
thermodynamic efficiency (chemical potential energy in versus kinetic 
energy out) for superheated and saturated locomotives, diesel electric 
locomotives, and electric locomotives.


> I'm no expert, but I think that a lot could be done to come up with a 

> more economical-to-build style of electrification for medium-speed heavy 

> freight service.  Recent electrification design has been in the context 

> of dense or high speed passenger operation which requires robust OH line 

> construction and electrical infrastructure, running up the expense.


It is my opinion that shortcuts in infrastructure are a bad idea.  Any 
heavy improvements, such as electrification, ought to be designed with 
excess capacity for the (hopefully) inevitable future growth in both 
freight and high speed passenger services.  Look at cities that only add 
a lane to a road when the congestion becomes intolerable.  By the time 
the work is done, the newly completed roads are already at or beyond 
capacity.  It is more expensive short term, but less so long term, to 
design and build ahead of current needs.


> I understand that there is a variety of reasons (overall thermal 

> efficiency, high but intermittant electrical loads and "unbalanced" AC 

> loads) why electrification has been problematic in recent years for 

> modern heavy-haul operations based on the concept of a small number of 

> extremely heavy trains running at relatively low speeds, i.e., the 

> Australian iron ore roads.  The high price and perhaps, future 

> unavailability, of Diesel fuel should warrant some new thinking.  High 

> voltage DC allowing for fewer OH line losses, lighter overhead line 

> construction - maybe even simple trolley wire, etc.  Think of the 

> interurbans  of many years ago.  Also, you wouldn't have to buy new 

> locos every ten or fifteen years!  However, one might have to go for 

> more, lighter trains to spread out the electrical loads.


A typical class one railroad ought to have enough traffic to balance 
out, at least partially, the load on the grid.  As mentioned above, 
running a small number of heavy trains is probably the worst case 
scenario for an electrified system.  The more frequent and numerous the 
trains, the more the load becomes balanced over the system.

Another point in favor of heavy electrification is that a diesel 
electric locomotive could be converted to electric by replacing the 
prime mover with appropriate transformers, rectifiers, etc.

On the subject of electrification, and to make this post at least 
somewhat relevant to the list, does anybody know why the Virginian never 
electrified further east than Roanoke?  Also, did the N&W have any 
electrified trackage, other than the former Virginian?

-- 
Kenneth Rickman - krickman1 at carolina.rr.com
Salisbury, NC

"You're a bubbling wealth of useless information!" - Holly Whitten