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The lede is a bit buried here: > Union Pacific plans to purchase 20 battery-electric locomotives for yard service If all they're doing is moving around a yard
by bobthepanda 5y ago
The lede is a bit buried here:
> Union Pacific plans to purchase 20 battery-electric locomotives for yard service
If all they're doing is moving around a yard, they're not ever very far from a charging station and they're moving at very low speeds.
- donarb 5y agoYard service is a perfect application for these types of locomotives. Diesel fired locomotives tend to sit around idling and burning fuel many more hours than they are being used every day. Diesel locos also tend to not be very fuel efficient when constantly stopping/starting around the yard.
- zeusk 5y agoAFAIK, most "diesel locos" are really diesel electric, with the diesel engine feeding a generator. Hybridization of locomotives seems like a no brainer since they can recover so much more energy with regenerative braking and can plan for braking to be recovery efficient.
- dogsgobork 5y agoAs I understand, braking occurs across the entire train, not just via the drive axles, so the hybrid regeneration method would be a considerable departure from normal operations.
- throwawayboise 5y agoYes, but diesel-electric locomotives have a brake mode where the "regenerative" current is shunted through big air-cooled resistors and exhausted as heat. Often used on downgrades to control speed without burning up the brake shoes. Recovering this into battery charge would be an easy win, though you might still need the resistors after the batteries are fully charged or if they can't absorb the charge fast enough.
- wiredfool 5y agoThis is where overhead electric is great, and why the Pennsylvania railroad ran full electric over the mountains back in the steam era. A coal train going down the mountain could mostly power the one going up.
- NickNameNick 5y agoI have the impression that engaging the airbrakes is a little bit all-or-nothing. They're great for stopping (relatively) quickly on level ground. But not so grest for controlling your speed. Big diesel-electric locomotives have large, actively cooled resistor banks, usually on top of the engine. When rolling down hill they run the electric motors as generators, and dumping the energy into the resistor banks. The mechanical brakes can't absorb that much energy - they'd wear out after a few minutes.
- s1artibartfast 5y agoresistors or capacitor banks? It seams like a resistor on a generator would just be a breaking load, and not actually capture any power.
- Animats 5y agoThese new locomotives are from Progress Rail, division of Caterpillar, and from Wabtec, which is Westinghouse Air Brake Technologies, 150 years old. They're just Diesel-electric platforms with batteries replacing the Diesel. "Replacing" may be just that. Few locomotives are built for yard work today. Most US switchers are old road locomotives, often half a century old. Sometimes they have a new power package. Progress Rail started as a locomotive rebuilder, changing out power packages for new ones, usually Caterpillar Diesels. Their electric seems to be a repower job of a classic General Motors Electro-Motive Division GT. Here's a video of their standard new Diesel repower job.[1] Lithium iron phosphate batteries, at least in the Progress Rail version. The heavier weight of lithium iron phosphate is a feature, not a bug, in a locomotive. Locomotives are built heavy to improve traction. The end result is not just a yard locomotive. Some of these are in test elsewhere for short-haul lines. Range maybe 300 miles. Another boring, but useful, technology, from old-line industrial companies. This is what makes the world go. [1] https://www.youtube.com/watch?v=6Kth3i2PGE0 https://www.youtube.com/watch?v=6Kth3i2PGE0
- jacquesm 5y agoHow is the reliability on those? The diesel-electrics are incredibly reliable.
- hakfoo 5y agoFor context, Progress Rail is what became of Electro-Motive Division when GM split them off, and Wabtec bought the locomotive division of GE a few years ago.
- algo_trader 5y agoIs the "electric" part of the diesel electric a commoditized technology? Is it a single motor or one per axis? How expensive is a 10MW electric motor? Asking for a friend Edit: for context - Tesla Semi is just 4x 250kw motors
- olivermarks 5y agoThe Tesla semi doesn't exist, those are theoretical specs https://www.inverse.com/innovation/tesla-semi-price-specs https://www.inverse.com/innovation/tesla-semi-price-specs
- stubish 5y agoProgress also make freight trains, which is a bit more impressive than shuffling railcars around (easily electrified) yards: https://news.ycombinator.com/item?id=30113639 https://news.ycombinator.com/item?id=30113639
- Aloha 5y agoIndeed, switching is a perfect application for this technology.
- rPlayer6554 5y agoIt's an initial step. I'm not sure if the technology would work for their main routes, but this at least is a step to test and evaluate how this technology works.
- bobthepanda 5y agoI'm not saying that this isn't a good step, but the headline just clipped off a pretty important piece of it.
- toomuchtodo 5y agoMain routes are better served by combusting manufactured carbon neutral fuels airlines (United recently flew a route with 1 engine burning this fuel) are testing, using hybrid locomotives with smaller batteries for kinetic buffers. A big Chevy Volt essentially. Electrifying US rail outside of switchyards won’t ever be practical, unless you could drive down the cost of electrified tracks with a third rail (overhead electric at this scale would be obscenely expensive).
- sfifs 5y ago> Electrifying US rail outside of switchyards won’t ever be practical, unless you could drive down the cost of electrified tracks with a third rail (overhead electric at this scale would be obscenely expensive). India has electrified almost 50,000 kilometers of track with overhead wires and this is increasing eabout 5000 km a year. China has almost 100,000 km of electrified rail track. So very likely whatever barriers to electrification there are in the US are largely self inflicted and maybe corruption or regulatory capture driven.
- bobthepanda 5y agoThird rails are even more expensive for freight railroads. * Double stack well cars sit very low. There are currently no third rail installations in the US that wouldn't get sideswiped by a well car. So their installation would basically mean forgoing half of freight revenue. * Third rails have to operate at lower voltages due to the fairly small clearance to the ground, and so they require more frequent substations than higher voltage overhead wires.
- api 5y agoPut overhead lines on even sections of long range rail lines and you could use it for long haul. Battery could be used to bridge between sections with power.
- seanp2k2 5y agoThen generate power at a coal or natural gas power plant. Until we get further along with renewables, the total environmental impact of replacing everything with electric today probably isn’t worth it. Example: https://www.reuters.com/business/autos-transportation/when-do-electric-vehicles-become-cleaner-than-gasoline-cars-2021-06-29/ https://www.reuters.com/business/autos-transportation/when-d... I remember having a heated discussion with someone about this at work, and it came down to where you were charging that Tesla and if you had rooftop solar (not even discussing the environmental impact of mfg + shipping + installation + support + useable lifetime of the solar panels, home batteries, and support accessories). And at the end of the day, moving around a 5000# Tesla or 6500# F150 Lightning takes a lot more power in any form than a 3400# Civic / Camry.
- bobthepanda 5y agoMy understanding is that bulk power generation is probably more efficient than having the motive power in the locomotive itself. There are also isolated use cases that the US railroads have been electrified for in the past (a lot of it was de-electrified to artificially boost revenues with asset sales in the midcentury). Namely * mountain tunnels; a fair amount of Western mountain tunnels can only accommodate one diesel train at a time due to ventilation, and the crews carry respirators and oxygen in case the train stalls inside * any sort of long sustained slope; downhill trains using regenerative braking can return electricity for those going uphill
- mlyle 5y ago> My understanding is that bulk power generation is probably more efficient than having the motive power in the locomotive itself. Almost certainly. But this probably evaporates once you need to pull significant amount of battery.
- seanp2k2 5y agoYep, battery energy density is still far off from fossil fuels. This is from 2012 but still relevant and why we don’t have electric commercial passenger planes, and probably never will until we make 10x gains in energy density: “”” Stored energy in fuel is considerable: gasoline is the champion at 47.5 MJ/kg and 34.6 MJ/liter; the gasoline in a fully fueled car has the same energy content as a thousand sticks of dynamite. A lithium-ion battery pack has about 0.3 MJ/kg and about 0.4 MJ/liter (Chevy VOLT). Gasoline thus has about 100 times the energy density of a lithium-ion battery. This difference in energy density is partially mitigated by the very high efficiency of an electric motor in converting energy stored in the battery to making the car move: it is typically 60-80 percent efficient. The efficiency of an internal combustion engine in converting the energy stored in gasoline to making the car move is typically 15 percent (EPA 2012). With the ratio about 5, a battery with an energy storage density 1/5 of that of gasoline would have the same range as a gasoline-powered car. We are not even close to this at present. “”” https://www.aps.org/publications/apsnews/201208/backpage.cfm https://www.aps.org/publications/apsnews/201208/backpage.cfm
- epistasis 5y agoWhile I agree about aviation, rail is an entirely different problem, and big heavy things move great. For freight in the US, the worst case segment I know about is ~700 miles. This can be handled with about 400-500 feet of battery cars, which is probably 5%-10% of train length. So the worst possible scenario is pretty close to feasibility with current tech. If railroads were to start investing in this level of battery, beyond saving a lot of fuel costs, they'd have a couple hundred MWh of battery at every rail station. This would be a significant grid asset, at least at the moment. In a decade, that level of storage is probably going to be extremely common. But in any case, there's significant opportunity for demand response payments, if not using the batteries for replacing peaking power on the grid.
- Seattle3503 5y agoGiven the efficiency of rail, is fuel even a considerable part of their costs?
- scsilver 5y agoAwesome, love to see this tech develop in these yards and expand as viable.
- dang 5y agoOk, we've unearthed the lede in the title above. Thanks!