chad thomas I put this to the forum last year and it was deemed unpractical (I disagree). Instead of trying to re-use the energy themselves, why not sell it to 'the grid'. The idea is to have a fleet of dynamic brake sleds captive on long decending grades. They would be added and removed in the same manner as adding and removeing helpers on the ascent. Then when they are set out at the bottom of the grade they could be pluged into a inverter or motor / alternator built to take the stored charge and feed the grid. Then the sleds would be returned to the top of the hill.
I put this to the forum last year and it was deemed unpractical (I disagree). Instead of trying to re-use the energy themselves, why not sell it to 'the grid'. The idea is to have a fleet of dynamic brake sleds captive on long decending grades. They would be added and removed in the same manner as adding and removeing helpers on the ascent. Then when they are set out at the bottom of the grade they could be pluged into a inverter or motor / alternator built to take the stored charge and feed the grid. Then the sleds would be returned to the top of the hill.
I've sat for over 3 hours trying to charge a trainline at Butler trying to build up enough pressure to do a Terminal Brake Test (and that was in the days of running with only 75psi), before the Trainmonster realized that we couldn't take 150 cars in the -5 degree weather.
Add to that tying up the main line, crew costs, etc. and it soon becomes not worth the savings.
I've often thought that converting to a third-rail type of power would be the cheapest way to electrify the nation's railroads, but then there would be all of the delays and liabilities due to fried tresspassers (but at least you wouldn't have to worry about ice buildup on the wires).
Z - I hit that in my last paragraph.
The bottom line seems to be possible, but not practical. Still, it never hurts to think on the outside of the envelope.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Ulrich Good point..maybe if the batteries were located on the ground near the grade...and the electricity is somehow funneled to them from the locomotive via a third rail that runs along the length of the grade..Those grade side batteries would then discharge their electricity when trains come in the other direction to climb the grade.
Basic concept is soound. If it were me, though, I'd use catenary instead - esp. on my Horse Shoe Curve example - for these reasons (in order):
1. Reuse immediately by an ascending train on an adjoining track or on the other side of the mountain;
2. Someday (soon ?) it will be electrified anyway - the catenary would avoid throwing this investment away when that day comes (which would happen with the 3rd rail). May as well get started now;
3. Less to get in the way of the track maintenance guys, and no gaps at turnouts, any road crossings (very few - mostly just company access roads anyway), bridges, trackside detectors, etc.
4. Reliability - less susceptibale to grounding from accidental contact, animals, vegetation, snow, etc.;
5. Safety - less risk of accidental contact.
Good thread and discussion !
- Paul North.
Paul, that must be a very big envelope!
Lots of good ideas here, but we seem to be forgetting one factor: recharge time! How long would these megabuck locomotives have to be tied up in order to fully charge them. The idea might work well for commuter trains that layover all day and night, but not for a locomotive that ties on to it's train in Chicago and runs thru to North Platte or Los Angeles.
In addition, consider how a battery becomes less useful the colder it gets (just like in your digital camera).
Also, don't forget that not all of the horsepower goes towards moving the locomotive--some of it powers the turbo, fuel & oil pumps, air compressor, lights, etc.
A little different idea...
The grades I am thinking of are long sustained grades like the west side of Donner, Black Butte to Redding, ect.
I think this could work. Even if just half the energy could be usefully captured and sold that's still a lot of energy.
Also the connection to discharge the batteries could be done inductively where the sleds would just have to be spotted in the right place to discharge without any electrical connection (this would require on board inverter(s) though.
Anyway, just thought I would throw that out there.........
Here is the regeneration threadhttp://cs.trains.com/trccs/forums/p/77887/931938.aspx#931938
Paul - 32 batteries x 13.8 would yield about 440V.
Of course, since the UPS is turning that 400+V into AC, transformers, etc, can make it what they want it to be. Before our last battery replacement, we had several bad batteries. That compromised the overall efficiency of the system, but it could still maintain the proper output voltage on full battery.
Then again - I know pretty much how the thing works, but I'm not an engineer.
What we can take from this appears to be that it would be possible to power a mainline locomotive strictly on batteries.
How efficiently we can recharge using the dynamics is another calculation altogether, as is determining the true duty cycle. How long will it take to recharge an idle battery locomotive that has discharged to the point where it cannot do the job? I'm pretty sure it took a day or more to bring our UPS completely up to capacity after the last battery change.
Which does bring up another economic consideration - batteries have a finite life. APC tells us it's 5 years for ours. At this point, it appears that batteries would still be cheaper than Diesel. What might tip the scales, however, might be the over all duty cycle. Assuming that the batteries could be charged in 16 hours after 8 hours of use, you'd still need 3 battery locomotives to every one Diesel in order to maintain 24 hour availability.
The technical term for feeding the power back into a catenary of third rail, for use by other motors or by the power company is 'regenerative braking', as opposed to 'dynamic braking', which is when the power generated is dissipated as heat. Regenerative braking is very much the way to go, provided that you have the catenary or third rail, and can recover (as Michael's post said) as much as 50% of the power. What neither regenerative nor dynamic braking can recover is any power used to overcome friction losses.
As to the feasibility of the whole thing, it is perhaps instructive to look at hybrid road vehicles (as it happens I own one -- a Honda Civic). For very short distances, some (but not all) hybrid road vehicles can use their propulsion batteries alone, but they all -- without exception -- are engine dominant; that is, most of the power for driving around comes from an internal combustion engine (plug-in hybrids will get some of their power from being plugged in, at the expense of much bigger batteries) and the propulsion battery is only used for peaking power. Situations and designs differ, but my Honda's battery will deliver about 10 horsepower for about 3 minutes, and then it's done. It's lithium hydride, and weighs about 300 pounds and is about 8 cubic feet (and, I might add, air-cooled). As batteries improve, the volume may come down, and the weight may come down a little -- but this gives one sort of a datum on these things.
A diesel electric submarine had batteries which were capable of over 1,000 horsepower for two hours. Impressive! Also, rather large and rather heavy (about 150 feet of a fleet's hull contained batteries under the deck).
Seems to me that the use of engine-dominant hybrids in rail service in such areas as switching makes a tremendous amount of sense. As I think I've mentioned before, though, it makes only very limited sense (in my humble opinion) in road service, and then only in drag applications in districts where there are significant, but relatively short and balanced grades.
Now if someone came up with the cash to electrify a substantial part of the nation's rail main lines (green Democrats, are you listening?), that would be a different story altogether. As an Aussie cousin of mine might say, "not bl___y likely, mate!"
I found this post by MichaelSol
If there is not an ascending train to use the power, the power is supplied back to the power company supply and is metered for credit. On the Milwaukee Road, up to 50% of an ascending train's power needs could be supplied by an equivalent train regenerating on the downgrade.
Yes, I was wondering the same . . .
Paul_D_North_Jr I wonder what the historiclal results were from, say, the Milwaukee electrification's regeneration over the two western mountain ranges, which was a big proponent and user of that principle back in the early pre-diesel days ? - Paul.
I wonder what the historiclal results were from, say, the Milwaukee electrification's regeneration over the two western mountain ranges, which was a big proponent and user of that principle back in the early pre-diesel days ?
- Paul.
Deggesty Paul, I did not follow your calculations closely, but are you taking battery efficiency into them? I don't think that you can regain when going downhill all the energy you expended going uphill. Surely, you are not proposing a perpetual motion system? Johnny
Johnny
Johnny (and others) - No, I did not take battery efficiency into account. I don't know what a good value would be to allow for that - a guess would be 90 % ? - and at that, the effect on all the results would be intuitive - need about 11 % more of eveything, etc. That doesn't change the basic results, and I didn't want to clutter up the approach with that detail. Again. it's easy to drop in and adjust for an appropriate value. As just a WAG, maybe get 2/3 of the energy back ? I wonder what the historiclal results were from, say, the Milwaukee electrification's regeneration over the two western mountain ranges, which was a big proponent and user of that principle back in the early pre-diesel days ?
Agreed, the downhill doesn't recover nearly all of the energy that was used going uphill - not only battery efficiency, but the various motor/ generator efficiencies, air/ friction braking for speed control on curves and restrictions and to come to a final stop, mechancal friction in many different places, air resistance, the locomotive's lights, air compressor, crew's air conditioning, etc., etc. I'm aware of the perpetual motion system trap - see my 2nd-to-the-last (penultimate) paragraph. "But for" those things, it would be close to a perpetual motion system - and if pigs had wings, . . .
Paul, I did not follow your calculations closely, but are you taking battery efficiency into them? I don't think that you can regain when going downhill all the energy you expended going uphill. Surely, you are not proposing a perpetual motion system?
Thanks for the data point, Larry. Let's see:
160KVA = 160 x Kilo (= 1000) x VA (= Watt in my simplified world) x 2 hrs. = 320 KWHrs. Since 1 HP = 746 watts = 0.746 KW, 1 KW = 1.34 HP. SO your battery set-up could theroetically put out 320 KWHrs. x 1.34 HP / KW = 429 HP-Hrs. - which is 429 HP for 1 hr., or about 215 HP for 2 hrs., etc. Wow - bet you didn't think it had that much capability in it, did you ?
And that's from 4 banks of 32 batteries = 128 batteries total. So each battery is good for about 429 HP-Hrs. / 128 batteries = 3.35 HP-Hr. per battery.
Or, another way: 320 KWHrs. / 128 batteries = 2.50 KWHrs. per battery = 2,500 watt-hours = 2,500 Volt-Amp-Hours per battery. At 12 volts output, that's 2,500 / 12 = 208 Amp-Hours per battery. (I have no idea how reasonable that is.)
Side-note - just curious: 32 batteries in series per bank at 12 volts each = 384 volts ?
Or, 480 volts / 32 batteries (per bank) = 15 volts per battery ? The correct resolution and understanding is probably in the effect of the 3-phases (as I noted above, I'm simple on this stuff).
Now, suppose we want to power a 4,400 HP loco equivalent with batteries for 1 hour. We'll assume that'll get it up whatever grade it needs to climb - at 15 MPH, that's 15 miles; if it's on a 2 % grade = 100 ft. per mile, that's a 1,500 ft. climb. There are surely longer grades, buit that's about right for most here in the eastern U.S., such as Horse Shoe Curve, Sand Patch, Washington Hill on the B&A, etc. Compare with Al Krug's tabulation of "Major Railroad Grades" at; http://www.alkrug.vcn.com/rrfacts/grades.htm
So it will need: 4,400 HP-Hrs. / 3.35 HP-Hr. per battery = 1,313 batteries. At, say, 20 lbs each, that's 26,300 lbs. of batteries = 13.15 tons. For a loco that can weigh as much as 210 tons (420,000 lbs. on 6 axles = 70,000 lb. = E-70 axles loading), that might be less than the concrete or steel that's sometimes added just to ballast the thing to enhance its tractive effort !
If we assume that up to half of the loco's weight could be batteries = 105 tons, then it could run for as long as 8 hours at that power output (105 tons / 13.15 tons of batteries per Hour at 4,400 HP = 7.98 Hours). At the same 15 MPH criteria, that would provide a range of 120 miles before recharging would be needed - or a vertical climb of 8 x 1,500 ft. = 12,000 ft. ==> more than enough ! In view of this, I'd say that about around half or 2/3 of that many batteries would be sufficient for 4 to 6 hours = about 50 - 70 tons worth of batteries = 60 - 80 miles range = 6,000 to 8,000 ft. climb - enough to get over Donner Summit is the "worst case", I suppose (even Tennessee Pass and the Moffat Tunnel climbs start at higher "base" elevations).
Next, the space requirements: Say each battery is about 1/2 of a cubic foot in volume - 1 ft. long x 8" wide x 8" high = 0.45 cu. ft. The 1,313 batteries for 1 Hr. capacity would need 1,313 x 0.5 = 657 cu. ft. For a loco that can be 10 ft. wide - say 8 ft. to allow for a walkway someplace plus venitlating space, etc. - and say 12 ft. high above the frame, that's cross-section of 8 x 12 = 96 sq. ft. So the 657 cu. ft. would need 657 / 96 = 6.84 ft. of length, say 7 ft. So 8 Hrs. of capacity would need 8 x 7 = 56 ft. of length of battery compartment; the 6-hour version would need 6 x 7 = 42 ft. long. Both are OK = "do-able".
To finish this off (such as when I have more time), it would be interesting to get actual power storage, prices, and weights for a representative battery - say, a deep-cycle marine battery - and see what the rough battery cost for this set-up would be, and how long it would take to pay for itself. In the meantime, as a single "for instance": If the batteries are $100 each, each 1 Hr.'s worth of capacity would cost 1,313 x $100 = about $131,300 in batteries alone; the 8 hours would cost about $1,050,00; the 6 hours would cost around $788,000. So that part has a prospect of being cost-competitive in the context of capital expenditure or investment cost.
Next - payback: Al Krug's "Locomotive Fuel Use" page at: http://www.alkrug.vcn.com/rrfacts/fueluse.htm says that a C44-9 in Run 8 will use 210 gals. per hour. At $2 per gallon (I know - RR's don't pay fuel use taxes, etc. - so substitute your own number instead if you want), that's $420 per hour. Now the 1 Hr. of battery capacity - 1,313 batteries at $100 each = $131,300 in cost. So each time those batteries are fully used for 1 Hr. = completely discharged and then recharged saves $420 in fuel costs. So, to recover that $131,300 of investment at $420 per hour would take 313 hours. Or, at only 1 trip per day, less than 1 year - actually, about 10 months. That's much better than I would have expected. Also, it's less than the number of cycles that most batteries can be expected to provide, so the batteries likely won't wear out before they pay for themselves. Even if the battery costs $200, that cost would be recovered in about 20 months at 1 trip a day - maybe a lot sooner if multiple trips can be made in a day, such as in a heper district (5 months at 4 trips per day, etc.).
Around now someone ought to be thinking about the "perpetual motion machine" / energy recovery aspects of this, as follows: If we start at the bottom of a grade with a fully-charged set of batteries in the loco; then go up that grade and use a significant portion of the batteries' charge to do that; then come back down that same grade again with a train in dynamic braking and (in a theoretically perfect world with no friction and no electrical resistance) so that the energy that was expended in going uphill is completely recovered and used to fully recharge the batteries; then what's to stop us from repeating that cycle many times, without having to add any (or much) more charge to the batteries from the outside ? Or, instead of helper service, if we run the train across a sawtooth or "hogback" profile, would it not on the downhills regain all the energy it used on the uphills, and so recharge itself over and over again as it goes (except for friction and resistance, of course) ? Said another way: What if I got a stimulus grant, built a prototype at the Juniata Shop, and worked with NS to test it in helper service on the Horse Shoe Curve ? Where would the flaws in this little exposition show up first and worst ?
I have a sense that I'm missing something here, though. Those of you with more experience, qualifications, knowledge, etc. than me - feel free to comment, correct, critique, revise, supplement, etc. as you see fit !
Ulrich Why not have the electricity generated by the traction motors stored in batteries on the locomotive or on a tender behind the locomotive? Instead of dissipating the energy as heat it could then be used later. The energy savings might be significant and I'm sure the engineers have thought this through...but what is the holdup on making this happen or why is it not feasible?
Why not have the electricity generated by the traction motors stored in batteries on the locomotive or on a tender behind the locomotive? Instead of dissipating the energy as heat it could then be used later. The energy savings might be significant and I'm sure the engineers have thought this through...but what is the holdup on making this happen or why is it not feasible?
As mentioned GE has a prototype:
http://ge.ecomagination.com/site/products/hybr.html
The Railpower Green Goat/Green Kid units also operated in a similiar way (although technically they were BATTERY DOMINANT hybrids whereas the GE is ENGINE DOMINANT (means exactly what it says))...the Railpower units were plagued with issues including battery fires...
As to the status on the GE unit, I know they had wanted to start building production locomotives by 2010 but I'm not sure about delays such as battery issues..they initially had lots of PR material but now seem to be more secretive..
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
henry6 Paul, it was the Lackawanna that had the tri powered locomotive used in Hoboken to Secaucus drag service. [snip]
THANKS, henry6 ! (I thought I had it right, though . . . ). They called it the "Kiddie Kar", too, if I'm remembering that right. Anyway, see:
Ohms vs. Ms Trains, July 1971 page 44 tripower locomotives on the Lackawanna ( "CRATON, FORMAN H.", DIESEL, DL&W, TRIPOWER, ENGINE, LOCOMOTIVE, TRN )
- PDN.
Point of reference.
My data facility has a UPS rated at 160KVA for two hours. It's three-phase (480?) in and three-phase out. The AC in is rectified, floated across the batteries, and re-converted to three-phase.
To get that two hours at full capacity there are four banks of 32 batteries each (the batteries in each bank are connected in series, the banks are connected in parallel).
The batteries are essentially automotive batteries, probably with some special tweaking.
The UPS is smart enough to calculate how long it should last at current load. Last time I looked, we were between 4 and 5 hours reserve.
The question is: how long would such an arrangement last if powering a locomotive? Obviously there are many variables. Notch 1 or Notch 8? How much dynamic braking is necessary to fully recharge a fully discharged battery? Would it be desireable to have the Diesels recharge the batteries if they (the Diesels) weren't being used at full capacity?
Paul, it was the Lackawanna that had the tri powered locomotive used in Hoboken to Secaucus drag service.
But I find it interesting how the idea of batteries and chargable or rechargeable batteries keep coming up in all eras and forms of transportation yet still no real formidable application.
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Batteries have always been the weak link in mobile applications using stored electricity. They are relatively heavy, and they are also relatively costly to produce, maintain, and recycle. Build a better battery and the world will beat a path to your door. You could certainly store dynamic brake energy in a battery, and use it to offset the use of diesel fuel when pulling, but the cost of doing so would be greater than the fuel saving.
I'm not so sure about the size of the battery pack needed being prohibitive, for the following reasons:
- Back in the early days of diesels non-steam motive power, I believe there were battery-powered locomotives - albeit of limited size and power, and maybe restricted to trolley-type operations. Also, the Erie had the Alco (?) Tri-Power locomotive - diesel-electric, straight electric (3,000 V. DC from catenary ), and battery.
- Don't one of the recent "green" hybrid-type locomotive designs or models have a large set of batteries to carry it between the charging cycles by the internal combustion prime mover ?
- Submarines were battery-powered when submerged until the advent of nuclear power - and there are still many diesel-electric boats ("Electric Boat" in Groton, Conn.). Although they have more space, that doesn't say it can't be done.
This needs a "back-of-the envelope" calculation to quantify this a little bit better.
Definitely the tare weight of extra batteries or car itself would be the defeating factor. BUT what if each car in a train...every car, every train...had such a battery for electric braking? Or if passenger car, batteries for lighting, etc.?
This subject certainly draws lots of people's interests....Already, creating braking from electrial resistence has releaved some expense by less use of the train brakes.....Perhaps in the future someone might find further savings from the dynamic brake system. Sure seems lots of people are thinking about it.
Quentin
There have been many people working on ideas for years. Batteries, Capacitors, Flywheels, ..... So far the only thing that has worked reliably is putting the power into the wire on an electrified railroad.
Good point..maybe if the batteries were located on the ground near the grade...and the electricity is somehow funneled to them from the locomotive via a third rail that runs along the length of the grade..Those grade side batteries would then discharge their electricity when trains come in the other direction to climb the grade.
The batteries required would need to be so huge that carrying around the extra weight would offset any advantage of capturing the energy. You would need something the size of a "B" unit to hold them, and even then they would not get you too far. Perhaps if/when battery technology advances, it might be feasible. But consider how huge locomotive batteries already are, and those are just to be able to start the motor!
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