Steam vs diesel pt II (or coal vs diesel fuel)

Trains Magazine General Discussion
1

Found this old email while looking in vain through my boxes of files for the ABC-Naco spec sheet on three axle bogies. It is a cost comparison of steam/coal vs diesel locomotive fuel costs (using 2002 numbers) provided by noted transportation and energy researcher Harry Valentine:

"Diesel costs about $1.00 per gallon (USA), or 141,531 Btu/$
A 3000 hp diesel loco uses 21,814,290 Btu/hr @ 35% efficiency.
Works out to $154/hr or $5.14 per mile @ 30mph.
#2 diesel has 19,000 Btu/lb

A loco using high grade coal ($40/ton – 675,000 Btu/$) runs at about 15% efficiency (GPCS firebox, etc). At 3000 hp, it uses 51,000,000 Btu/hr @ 15% efficiency, or $75.41/hr fuel cost. At 30 mph, this works out to $2.52 per mile. High grade coal has up to 14,000 btu/lb.

A loco using low grade coal ($5.00/ton – 3,520,000 Btu/$) will run at about 12% efficiency (GPCS firebox, insulation, etc.). A 3,000 hp loco would use 63,625,000 Btu/hr @ 12% efficiency, or $18.18 per hour. At 30 mph, this would be $0.61 per mile."

If we upgrade the relative fuel costs to reflect current pricing, how does this dynamic change?

If we take out the high grade coal section and just focus on diesel vs low grade coal, the 2002 numbers suggest that the cost per mile of using diesel was 8 times the cost of using low grade coal. This is probably 10 times difference by now.

At what point would the fuel cost differential swing in favor of steam over diesel?

2

Figure in maintance and rebuliding infastructe that was removed te fact that every engine has it own crew and and water costs steam still would cost more.

3

Details! Details!

4

Assuming you’re talking about reciprocating steam and not diesel powered by powdered coal (Dr. Rudolph Diesel’s original concept) as mentioned above, it’s the infrastructure that killed steam. NYC loco chief Kieffer ran extensive tests w/ Niagara, straight electric, E-7 and FTs. The E-7s were run in 2 and 3 unit sets. 2 unit sets were marginally cheaper than the Niagra but couldn’t match its performance. 3 unit sets marginally out-performed the Niagara but cost more. The most effecient was the straight electric. When infrastructure was factored in (especially the cost of expanding the 25 miles or so of Grand Central electrifification system wide) the diesel won, and that’s comparing a steam infrastructure already in place. Added to that the availablity factor w/ diesels (top off the tank, clean the windshield and send it back to the depot. If it’s a back to back AA set it doesn’t even have to be turned) and steam’s fate is sealed.
If somebody who had the design and operation of steam engines down as cold as the N&W gave up on them, that should settle the argument. (And let’s not forget that we’re comparing 1500 and 2000 HP per unit engines ca. 1950)

5

Try thinking in terms of modern steam locos vs classic steam locos. Support infrastructure isn’t as crucial as it was back then, because it is easier now to truck n’ pump water to a site, and coal can be brought railside via internal mechanisms and modern technology (think plug 'n play container loads of coal, when one goes empty you just lift it off and put on the next loaded one).

I can see where certain people continue to make the comparison based on modern diesels vs classic steam, when the proper context would be modern diesel vs modern steam. Context, people, context!

6

Perhaps it should be noted that the $5.00 and $40.00 coal prices are mine mouth prices. The $5.00 is currently $10.00 or $12.00 and you get that price if you happen to be running the locomotive past a PRB mine. I haven’t forgotten that the price of diesal is about double the one buck figure.

Have the steam designers work out the T2?

7

Dave-seeing how there is no modern steam, we’d be able to imagine it any way we wish? Hmmmm, suddenly the “modern steam” is looking pretty good.[;)]
Note how I got that there quote thingie to work.[:)]

8

A few assumptions are being made here that shouldn’t be. Modern recip GPCS steam (the term refers to ‘gas-producer combustion system’, the concept being originally developed by Argentinian Livio Dante Porta and then refined by others including David Wardale) is only going to approach 15% when run continuously near the speed corresponding to best cylinder efficiency – there is some broadening of the curve with sophisticated valve gear, but it’s still likely to be well north of 35mph – with all the Rankine-cycle heat-recovery stuff expensively in place and operating at full balanced effectiveness. (Don’t think I need to mention maintaining a good thick firebed, stable overfire air, consistent fuel quality, etc. etc. etc. for GPCS) Harry did not include any expense for ash handling (either at rear or front of the gas path) or air-pollution reduction in his estimate for fuel cost, which is not really sensible imho; you need to normalize the cost of fuel per ton for the entire cycle. One may note that this is a significant incentive already for using oil firing – and not coincidentally, often ‘light-oil’ firing, which usually means diesel – in STEAM locomotives, and if you look at, say 8055 in Europe, 3985 at UP, and the reactivated T1 in the Pacific Northwest, you can get some understanding of why coal-burning locomotives get converted despite the supposed ‘cost advantages’ of the solid fuel… the financial analysis of 8055’s operations being particularly significant as it uses the full cost of operations in a specific service, putting fuel cost into proportion as only about 5% of overall operating expense. Remember the old telephone slogan “NOW where’s my big savings?..”

It should be noted that #2 diesel inherently has preparation cost in its refining, and that impending air-quality requirements for diesel will include factor costs for things like urea/nitrogen and for sulfur reduction or elimination – but these are much easier and likely to be less costly than equivalent operations on solid

9

Regardless of the cost of fuel, the cost of building a coal burning locomotive today would be much higher than the cost of a diesel locomotive, and with increasing demand, the cost of coal would rise, not to mention any possible charges for production of greenhouse gases. Add to this the difficulty of transporting coal compared to oil, I don’t expect that coal burning locomotives will reappear on a commercial basis. If a decision was made to move transport to a less strategic fuel, it is quite possible, but I’m not holding my breath.

M636C

10

Here is another approach, but again billions might be required to implement it and millions just to try it experimentally. The attempt would be to bring power plant technology to locomtives:

  1. AC electric transmission, with electric and electronic components as similar to modern AC diesel-electrics as posssible.

  2. Tubine use of steam, not reciprocating, with the basic disadvantage of turbine operation, a narrow range of loads and operating speeds that are efficient, overcome by use of say three turbines, of .125, .25, and .50 total rated locomotive turbine horsepower, giving a total of eight efficient throttle positions:

,125m .25, .375, .50, .625, .75, .875, and full power.

  1. High boiler pressure, with the best of modern metalurgy used to insure boiler and firebox longevity.

  2. Use of the best current practice diesel-locomotive truck and suspension systems to not only insure a smooth ride for the engineer but for the boiler and firebox as well!

11

Do a full life cycle cost analysis for both, from drawing board to scrappy’s torch. Include not only fuel, but maintenance and labour costs. Then you’d have a fairer comparisin of the true cost of steam v diesel.
Not sure how you’d account for the convenience factor of diesels. (switch on and go v steaming the engine up before it’ll move)

12

You can run the smallest of the three turbines in my scheme at idle and then power it up and use it to power up the other two when needed. This would be similar to diesel idling.

13

Why would you even consider external combustion steam when all you have to do is install a coal liquifaction plant, like SASOL has been doing for decades in South Africa, and you make diesel fuel (or gasoline) directly from the coal. OPEC problem solved.

On top of that the price of oil is getting high enough that the recovery of petroleum from the oil sands and tar sands is becomming economically feasible. The US and Canada have large supplies of both. Again, external combustion steam need not apply.

14

Dave,
GE Evolution series are more fuel efficient that that, and most of the newer EMD too, so unless you are just stuck on the 3000hp number, the second line figures no longer work, which throws the whole idea askew.

Now, that aside, who is going to finance the building of a modern steam locomotive?
Keep in mind that with out contractual guarantees, no one will invest in the tooling, manufacturing process, and development, beyond the design stage.
Even with CAD, and today’s newer materials, carbon fibers, stronger aluminums, better design tools, your still looking at a major investment in building a prototype/test bed.
And if you get the idea off the drawing board to the actual build stage, almost every piece will be a one off, no one is set up to cast side rods, drivers, things like that…who build boilers like that anymore?
Even if all of these items are built with new materials, on a new design, you still need the workers with the knowledge to assemble it, and a place to build it.
You would have to train from scratch all your maintenance people, and all of your assembly line workers
I also doubt EMD, or GE, will rent you space.

Last, although in another thread, you and Michael argued that, in some theoretical instances, steam was more efficient than diesel, and yes, some railroads retired steam locomotives way too soon for the machine to have earned back its purchase price, the fact is you might make a steam propulsion plant more fuel efficient than a diesel one, but no matter how well built or designed, it will always be more maintenance intensive and parts cost/service cost expensive.

There is no structure in place to build a modern steam plant designed specifically for a locomotive application that will meet all the criteria of today’s railroads in terms of versatility and ease of use, there is no system in place to provide and install spare parts, and no system in place to service and maintain such a machine.

So

15

Ed and Overmod have covered most of the salient points (no surprise!) so I won’t beat on them. However, imho they have underestimated the difficulty and expense of getting a moving solid fuel burning powerplant (that is, a coal fired engine, and it really doesn’t matter if it’s recip steam, steam turbine, or gas turbine) to burn cleanly at a wide range of power settings with a wide range of fuels. While many railfans just love to watch a coal-fired engine with that billowing smoke, the air pollution folks are not quite so enthusiastic about it. Even in stationary powerplants, which can afford to have heavy, bulky, and somewhat delicate processes and controls, meeting today’s air pollution requirements is no picnic. On a coal fired railway engine? Oh dear… while as both GE and EMD have shown, doing it with diesel is entirely feasible, and at overall prices which are competitive.

16

Interesting discussion.

17

Actually, developing sensible firing controls for a proper modern boiler is not particularly difficult. Much of the difficulties with packaging would have to be handled by extensive use of EGR (but of course you get a great deal of combustion-air preheat for free when you take the trouble…) and of course you have to keep relatively close tabs (and take prompt action when necessary) on operations and maintenance. But one of the principal points about any really modern locomotive steam-generator system is that it would not depend solely on exhaust for the induced draft, and would have fully modulated and proportional draft control – not just to save fuel and keep pops from lifting, but to control differential stresses in the steam-generator structures when changing power levels.

Much more significant, imho, than the draft issue is that of packaging the necessary systems for Rankine-cycle heat recovery into something that fits on a locomotive with sufficient power for its weight and length. It gets a bit easier if you’re using bogie-mounted AC drive with components in common with diesels, and you can then put many of the subsystems on the ‘tenders’ and use their weight meaningfully both for traction and balance…

Dave – I think you’re barking up the wrong tree, although your idea isn’t as odd as the Fell locomotive. I see the wave of the future in that line of development as being (relatively) small IGCC, with ceramic turbines/EGR for the combustor, the steam turbines as the bottoming cycles (including the ancillaries), and imho a further ORC bottoming that to keep the steam water rate under control. The point made about fuel synthesis is a valid one – but it is equally possible to synthesize a less-‘refined’ liquid fuel that will burn nicely in an external-combustion burner – including combustors feeding a ceramic gas turbine plant – but would gum up any modern diesel capable of passing Tier 2 emissions. Same for fuels derived from the usual-suspect renewable sources – it’

18

There is a significant difference in pollution effects between external and internal combustion. Much of what is seen out of a steam locomotive is simple solid particulate condensing around water vapor – much like clouds.

Internal combustion produces much more insidious types of by-products. While coal in its solid form is a “dirty” energy source, the diesel engine is a particularly dirty means of producing energy.

EPA standards regarding locomotive emissions are dreadfully low, simply because of the extreme difficulty of cleaning them up. Railroads have successfully sought exemptions from the standards applied to everyone else, because they can’t fix those diesel engines in a cost-effective fashion (even though truckers have managed).

"Diesel exhaust is a mixture containing over 450 different components, including vapors and fine particles. Over 40 chemicals in diesel exhaust are considered toxic air contaminants by the State of California. Exposure to this mixture may result in cancer, exacerbation of asthma,

19

I don’t have time to check this (it’s all over the Web) but I distinctly recall that the Tier 3 standards in, what is it, 2012, will apply particulate emission reduction to new locomotives. There are several perfectly ‘good’ solutions that can do this, including regenerating traps (admittedly requiring heroic cross-sectional area for max flow and some fancy connections!) and the general NH3-injection stuff. (I am of the opinion that it should be remarkably easy to keep ammonia slip to an absolute minimum on a locomotive, as opposed to just about anything else using compression ignition in a practical vehicle – hint: use civil geo combined with good NDGPS and engine-acceleration control mapping, and you can easily predict precisely how the exhaust stream will be behaving at any point… of course, it’ll help if the Government underwrites big, big chunks of the implementation of something like that, but of course, they already are…

An additional point bolstering Michael’s is that external-combustion fuel burn can be greater than that stoichiometrically optimal – or even practically possible – in a confined internal-combustion motor. That, in turn, means not only that you can get higher output from your actual engine, but also that (with some additional care, such as via large overcritical-water mass in a ‘boiler’) you can develop significantly higher momentary horsepower or TE out of an engine of given size, NOT something diesels do well, or will ever do well…

BTW – Michael, do you have a graduate degree from the Netherlands circa the early '90s?

20

All the arcane discussions of fuel and how they are burned in the locomotive to gain power to the rails are all very interesting, but I would suggest that in most things as the complications and demands of a particular system of power generation go up, so do the costs, especially associated with the infrastructure needed to support a particular system. It was the infrastructure of steam, fuel delivery to the locos and frequency of the need to refuel, plus the maintenance and the number and quantity of skilled employees, not to mention their associated employment costs , coupled with the hours available to run for the locomotives, that when factored against the diesel locomotive that finally forced the change to diesel from steam propulsion.
Once past the N&W and C&O experiments with turbine steam turbine-electric propulsion [in the 1950’s]. Ross Rowland’s attempts to generate new interest in steam propulsion, were the first flirtations with new steam technologies in many years.
The Union Pacific’s Steam Heritage program[ a class alone] is a last serious steam propulsion program, and it requires a real commitment on the part of Union Pacific to make it work.
Sam