Note also the 64 comments (as of this moment) to the article on another ‘tab’ at the top.
From the middle of the article (and I’ve posted this statistic here before) - emphasis added:
“A gallon of diesel fuel cost an average of $3.97 last year, according to federal statistics. The equivalent amount of energy in natural gas cost 48 cents at industrial prices.”
For a diesel unit using 1,000 gallons of fuel per day, that could be a fuel cost saving of about $3,500 per day [1,000 x ($3.97 - $0.48) ]. For even just 1,000 units of that 6,900 unit BNSF fleet, that would be as much as $3.5 Million per day !
I crunched the numbers last night. A full 4000 gallon tank of diesle fuel would cost the railroad $15,880. For the same amount of liquidied natural gas the cost would be $2672.50. That is 1/6th the cost of diesel.
Purchase of gas is one thing. Having it on the train as locomotive fuel becomes another issue. Diesel, when a fuel tank gets ruptured - and they do, more frequently than we would like - will just spill the fuel to the ground with minimal chance of fire. A ruptured LNG fuel tank (if we use the same fuel tank location on locomotives) would have a high and relatively immediate chance of fire as LNG released to atmosphere is just looking for the opportunity to become a flammable gas.
…and the additional hardware…and the fuel tender…and the transloading equipment… (The things will run in tightly controlled corridor and be fueled by a limited number of LNG vendors)
Will be interesting to see if these things become orphans or outlaws…
According to the article, LNG is less likely to catch fire than gasoline, but it is more likely to than diesel. Diesel does catch fire during detailments. My point is that that it will be up to BNSF and its contractors to come up with the safeest method of using LNG. This is an engineering problem and I am sure BNSF will not go into this without a lot of engineering and testing.
[?] [;)] If all this hype about LNG does take place, I wonder if the savings of the current price of LNG will skyrocket passed the price of diesel. The oil companys will surely tryto get a huge piece of the pie. I seem to recall a railroad tested a yard switcher some years past and must have failed. Very interesting.
A little more, blah, blah, blah. And how will the pipeline affect this when built and in operation, if any affect? The pipeline will be built. Efficiency rules.
Yes, but remember the liquid itself is cryogenic, and it will ‘further’ cool as it expands. That often keeps the effective critical transition temperature for combustion either ‘out of range’ or the combustion itself self-limiting. Given enough time, of course, the critical-mixture issues come up, but those are really significant mostly in enclosed spaces.
There’s been extensive discussion over the years about ways LNG tanks need to be hardened against various shocks. One point is that the inner liner, exposed to cryo temperatures, becomes very brittle unless made of specialized material or appropriately treated. On the other hand, even since the '60s there have been insulating systems that will (for example) keep liquefied methane happily liquid even at hypersonic skin temperature for enough time to be significant. More recently, there are versions of multiple-shield film insulation that accomplish this level of quality with a very small thickness, allowing better ‘armoring’ of the outside shell without concern for more than ‘spot’ cold resistance.
The great problem I foresee is people shooting at the tanks, which will cause spot leaks no matter what you do. The obvious ‘fix’ is to put liquid air-curing monomer somewhere between the outer shell and the outmost layer of insulation, like a self-sealing fuel tank, and allow it to foam or harden to reduce any liquid LNG flow through the breach. (The heat of the bullet strike may allow a brief flame plume, but it will not sustain at cryo temp in air even with the car moving).
A key point – don’t know if it’s been addressed yet – is that it’s comparatively easy
LNG tanks will be larger than diesel with the same total energy. Diesel is about 36 MegaJoules/Liter and LNG is 26 MegaJoules/Liter. Along with the cryogenic features of the fuel tank, this will require additional space for the fuel to go the same distance.
But here in Minnesota, the LNG won’t need to be refrigerated most of the year. It is plenty cold here. -3 F here this morning…
ATSF and UP both purchased 1200 HP LNG fueled switchers which have Caterpillar Natural Gas Engines from MK RAIL(now MPI Wabtec). These were operated by both RRs in the LA area for a number of years and were, by all accounts, techically succesful. In fact all of the units are still being operated by the Los Angles Junction Railway:
Of course they were; I don’t think there has ever been anything about the ‘engine’ side of the discussion that was ever in doubt. Lower required compression, fewer deposits in the exhaust or oil – well-established since before I went to college that wear on the engine is much less and maintenance much easier than for diesel. (Or any liquid fuel in ignition motors, for that matter).
On the other hand, remember that the LA Basin switchers were put in for air quality reasons, not efficiency as a normal railroad would define it. And fuel capacity being radically restricted by density packaging and insulation is much less of an issue in switching than in long-distance road power.
The ‘technical reasons’ likely hinge on how the fuel is provided, and how it is stored with a minimum of tare weight increase. My solution (many years ago, now) was to put the cryo on a road-slug chassis, perhaps with appropriate ‘automagical’ derating of the traction motor power with decreasing fuel weight. I still think that, rather than the converted-tank-car-as-‘tender’, is a better and overall less expensive and risky, approach to the issue.
Natural gas will not “compression ignite” Locomotive diesel engines therefore require addition of spark ignition with associated timing or a pilot stream of fuel oil, which will compression ignite and in turn ignite the gas. Both of these schemes were tried by EMD and others many years ago but were abandoned as impractical at the time. Replacing the diesel engine with a specific natural gas engine on new or rebuilt locomotives has a better chance.
Gas turbines are another alternative that have a lot of advantages and could be practical with the low price of LNG,
See my notes on this in the ‘other’ forum thread with this title, over in 'Locomotives". I go into some details of required conversion mods there.
I did not note some of the arcane details of best ignition in large cylinders, or discuss other practical aspects of the conversion, but you will get the general idea of what’s what. Yes, you need either a heat or flameholding source – as noted for producer-gas motors back to time almost immemorial. Personally, I think turbocharging and high compression have some value, but you would be surprised how good a detonation wave you can get from compressed methane. (Hint: Aurora)
Gas turbines seem to have been the choice of benighted people trying to use CNG rather than LNG, which I think is dumb. One great modern advantage is that small ceramic turbines are now OTS available and make modular applications incredibly easier than they were when I played with turboshaft gensets (eight to an E8 shell) in the 1970s. You would also want to run effective Rankine-cycle bottoming on the turbine exhaust (hence my reference to GTCC, which that is) which, even at locomotive scale, can give you very good overall thermal efficiency even when the turbine proper is only idling.
See my notes on this in the ‘other’ forum thread with this title, over in 'Locomotives". I go into some details of required conversion mods there.
I did not note some of the arcane details of best ignition in large cylinders, or discuss other practical aspects of the conversion, but you will get the general idea of what’s what. Yes, you need either a heat or flameholding source – as noted for producer-gas motors back to time almost immemorial. Personally, I think turbocharging and high compression have some value, but you would be surprised how good a detonation wave you can get from compressed methane. (Hint: Aurora)
Gas turbines seem to have been the choice of benighted people trying to use CNG rather than LNG, which I think is dumb. One great modern advantage is that small ceramic turbines are now OTS available and make modular applications incredibly easier than they were when I played with turboshaft gensets (eight to an E8 shell) in the 1970s. You would also want to run effective Rankine-cycle bottoming on the turbine exhaust (hence my reference to GTCC, which that is) which, even at locomotive scale, can give you very good overall thermal efficiency even when the turbine proper is only idling.
The problem is dilithium, while present in quanity here in the US, is just as abundant and cheap and cheaper to mine in the middle east, where a group, DOPEC, has formed and controls the supply.
We have the technology; they have the raw material…sounds familiar.
If we could just get that darn pipeline built from the north to Texas, we could refine all of the stuff you need.
Gas turbines look to be a good way to utilize LNG, particularly with the genset approach you mentioned on another thread.
I do have a couple of questions:
#1 Aircraft gas turbines typically have a limit on the number of starts before requiring an overhaul, would there be a way off increasing that limit for locomotive turbines? (Possibly turning the turbine faster during the start?)
#2 Allison was promoting steam injection on their 501 turbines some 25 years ago. Might something like that help with locomotive turbines to improve thermal efficiency, reduce NOX and reduce exhaust temperatures?
The only problem Scotty ever seemed to have with Dilithium, was keeping his crystals charged up to make the Enterprise go fast!They always seemed to be able to find them…