10 ms·

Future trains could provide carbon capture

87 points by noplsbecivil 4y ago

noplsbecivil 4y ago
After reading this article, I was wondering if a similar approach could be used on cars? Could the braking energy be used in a similar way? What about for trucks?
- johnday 4y ago
  Surely it is more efficient to store the braking energy in cars for acceleration, which then reduces the amount of fossil fuels burned in the first place? (AIUI this already exists) In fact i'm not sure why that wouldn't also apply to the trains...
  - stormbrew 4y ago
    I assume the issue is trains that aren't electric, and I assume even most electric trains don't have significant energy storage on the train itself, so might not really have much to do with energy from breaking. It probably especially makes sense that freight trains running off fossil fuels won't even consume much electricity at all (just enough to operate instruments in the locamotive?), though presumably passenger trains could make use of it. Maybe there are barriers to electrification of some trains in some areas.
    - Glawen 4y ago
      Tramway are regenerating power and injecting them back in the grid when they brake. I think electric trains do it as well, the resistor grid is only used when not enough power in generated
    - pmyteh 4y ago
      Most electric trains only have a small service-and-emergency battery and don't have significant energy storage. For AC electric locomotives it's now standard to return electricity to the grid when using regenerative braking; that's harder with DC electric traction but is done in some circumstances (in others, the generated electricity is dumped into heat via a resistor bank). The main barrier to electrification is the high upfront capital cost of the electrification works, set against the longer-term per-train return in lower fuel and locomotive/multiple unit costs. Lines which are not intensively used are difficult to justify electrifying on a financial-returns basis, and that probably includes most of the world's long-distance freight lines.
    - jimktrains2 4y ago
      Nearly all fossil-fuel burning train engines (I think the exception being a handful of hydraulic engines in Germany?) are diesel-electric, which use the diesel engine to turn an electric generator to power electric traction motors. (Dynamic breaking is when those traction motors are used as generators, but that electricity is usually dissipated as heat immediatly.)
      - jimktrains2 4y ago
        Nearly all non-steam fossil-fuel burning train engines*
elric 4y ago
What's the market for this? Are parts of the US unable to electrify trains for some reason? Surely the easiest way to capture the carbon is not to emit it in the first place, and if you are going to emit it, you might as well do it in a stationary power plant.
- fomine3 4y ago
  Even if fully electrified train is difficult, hybrid and energy regeneration could be better.
- AlgorithmicTime 4y ago
  Those ridiculously long distances in the middle of nowhere are not really well suited for overhead electrical wires.
- AnimalMuppet 4y ago
  > Are parts of the US unable to electrify trains for some reason? It basically comes down to cost. The electric infrastructure costs per mile to install, and per mile per year to maintain. The benefits come per train. If you don't have enough trains per day, it's not economical to electrify. There are some places, like the Union Pacific around North Platte, where you'd think that electrification would be a natural. But the problem is that 90 miles east of North Platte, and 20 miles west of North Platte, the lines split, and the traffic density goes down. Switching between electric and diesel locomotives twice in 110 miles adds operating cost.
  - kitten_mittens_ 4y ago
    Even in Boston, the metro transit authority (MBTA) has talked about the options for full electrification of commuter rail costing 18 billion+. https://d2o8eokdkim9o8.cloudfront.net/sites/default/files/2019-10/rail-vision-alternative3-oct2019-accessible.pdf https://d2o8eokdkim9o8.cloudfront.net/sites/default/files/20....
- elric 4y ago
  Not sure why AlgorithmicTime's comment is dead, so I'll reply here. Long distances are probably tricky to electrify. I don't know enough about US railroads (what little I know of US railroads comes from playing Ticket To Ride) to comment on the feasibility, but there are very long electrified railways in China and Japan, across difficult terrain. There is probably not much benefit in feeding electricity from regenerative braking back onto the overhead line if it's a very long segment with only one train (no one to use the power + transmission losses). I wonder at which point diesel becomes the cleaner option here, if ever. One the one hand, you have to lug a lot of fuel around over longer distances (or you need refueling infrastructure). On the other hand, transmission losses can be significant.
digdugdirk 4y ago
How/why do trains not already recapture the energy created from braking?
- AnimalMuppet 4y ago
  Electric trains do. For the rest, they don't because of lack of storage. A diesel locomotive has a huge engine block, a generator, a large radiator, and electric motors on the axles. You can turn the motors into generators when you want braking, but where are you going to put the electricity? All the space (and weight) is already used. Yes, they have batteries - enough to crank the engine when it has been turned off. Not enough to run the electric motors on the wheels, though.
  - azdle 4y ago
    > but where are you going to put the electricity? Bring back the tender[0], but fill it with batteries instead of coal. Or better yet, intermodal container shaped batteries that could be swapped for pure electric long distance trains. [0] https://en.wikipedia.org/wiki/Tender_(rail) https://en.wikipedia.org/wiki/Tender_(rail)
- detaro 4y ago
  Modern electric passenger trains do - they can dump power back into the grid, and have enough motors to do a good chunk of braking with them (And e.g. for the German high-speed trains they plan the braking points such that they try to avoid using lossy brakes in normal operation). If you don't have a grid as "storage", you need to carry it, and that's a problem. And freight trains obviously only have motors in the locomotive(s) and do the distributed braking on the cars mechanically, so a good chunk is lost even if the locomotive can do it.
  - deleted 4y ago
    [deleted]
ZeroGravitas 4y ago
Trains can be fairly easily electrified (via overhead rails) and hydridized with batteries. Generally they're diesel electric in the first place, so you're just switching electricity source which makes it a smooth transition. So I feel this will lose to batteries, which can be use to brake at every motor, and so can be easily distributed along a train. (Though you don't need batteries for regen braking, you can feed the power back to the grid if you have a connection). And once you have a decent sized battery you can charge from overhead lines when available, which opens up other possibilities. https://www.alstom.com/press-releases-news/2021/9/alstom-presents-its-battery-powered-multiple-unit-train-saxony https://www.alstom.com/press-releases-news/2021/9/alstom-pre... > The studies have revealed, for example, that a large proportion of the lines currently operated with diesel vehicles include non-electrified sections of well under 60 miles. The use of the existing catenary infrastructure allows battery-powered electric vehicles to be operated on these lines without major upgrades to the existing infrastructure. Extensive travel dynamics and energy simulations were also carried out as part of the project. A similarly wacky concept, that I perhaps like is shipping full batteries to places where energy is expensive via train. So charge up a train battery from solar as it travels east, then feed that back to the grid as you meet a post sunset peak. Possibly wouldn't make sense if you were to do it for it's own sake, but if you already have a network of battery trains that can time their charge, you can probably save a reasonable amount of money by optimising when/where you charge based on time of use and demand response events. Coordinated Demand Response of Rail Transit Load and Energy Storage System Considering Driving Comfort https://www.researchgate.net/publication/347975248_Coordinated_Demand_Response_of_Rail_Transit_Load_and_Energy_Storage_System_Considering_Driving_Comfort https://www.researchgate.net/publication/347975248_Coordinat...
- lstodd 4y ago
  Batteries are no-go. Typical electric locomotive is like 5MW sustained for multiple hours. It wouldn't be able to pull just its own batteries for any reasonable distance. 60 miles of catenary is way cheaper than wasting energy pulling dead weight that batteries are.
  - ZeroGravitas 4y ago
mdavis6890 4y ago
I still do not understand how any human-developed carbon capture techniques is going to be better or more efficient than just planting a tree. A (living, growing) tree can capture quite a lot of carbon for almost no cost, directly from the atmosphere. More generally, vegetation biomass growth is carbon (and hydrogen) capture in action on planetary scale - almost for free.
- TremendousJudge 4y ago
  Or at least create the hydrocarbons in a factory, sucking the carbon from the atmosphere, and using energy from renewable sources or something of the sort. This would be carbon neutral at least, and still allows liquid fuels to be used. I have never seen anybody invest into this research. Somebody please correct me if I'm mistaken here.
  - noplsbecivil 4y ago
    Not quite there yet, but https://solugen.com/ https://solugen.com/ are trying
- L_226 4y ago
  Because trees cannot be grown just anywhere, they require specific [land, water, nutrient] conditions that also happen to be the same things that are already under pressure from our civilisation. This is caused by things like extensive monocrop agriculture, grazing etc. Furthermore, trees do not necessarily sequester carbon beyond their lifespan - the sequestration is an additional process that may or may not occur naturally. Think of old trees dying, falling down and decomposing vs old trees dying and being covered by mud.
- ch4s3 4y ago
  Photosynthesis is pretty inefficient and trees release the CO2 when they rot, so they aren’t great for long term storage. At certain phases of growth, forests are actually carbon positive. DAC can bind carbon to rock or pump it deep underground where it will stay potentially forever(on any meaningful human timescale). You can also directly account for the tons of CO2 removed by DAC which makes it more used for carbon trading schemes that financially incentivize capture.
TremendousJudge 4y ago
I really don't understand how carbon capture can make sense, in terms of thermodynamics. Burning hydrocarbons releases energy, plus carbon dioxide and water vapor. Capturing the carbon dioxide back would, in some way, require an equivalent amount of energy to be spent, right? Where is this energy coming from? In this case, it's actually mentioned in the article (unlike many other carbon capture proposals): add regenerative braking to trains -- plus make the engines work harder by adding a lot of extra air resistance for the filtering system. Meanwhile, the European electric grid -- and therefore its electric trains -- is partly ran by burning fossil fuels (not to mention the manufacturing processes for the proposed batteries and filters). So you're burning carbon in order to get carbon out of the atmosphere -- there's no way that equation comes out as a net negative for emissions, there are inefficiencies everywhere. This is honestly one of the most compelling carbon capture proposals I have read, and it still doesn't make sense to me. What am I missing here? Why is this being taken seriously?
- kitkat_new 4y ago
  the energy is coming from the sun. And you are right... even worse: putting carbon emitted back into the ground requires not only the energy gained through burning, but several multitudes of that. That's why not burning it in the first place is almost always better. Still, carbon capture is necessary, because there are things that are extremely hard to substitute. Further, if we don't go for negative emissions, we will have at least 4 degrees of warming (even if we stop emitting now). Just watch out for greenwashing
- photochemsyn 4y ago
  Artificial photosynthesis is absolutely required in several sectors, if you want to eliminate the use of fossil fuels. International air travel is the main example, so is space travel, and global shipping is a little behind. There's no way to fly passenger jets over the Atlantic and Pacific Ocean using battery power; the density is just too low. Likewise, if you want to have SpaceX continue to launch large methane-fueled or RP-1 fueled rockets without fossil fuels, capture of atmospheric CO2 and conversion to hydrocarbon fuel will be needed. It's also a way of storing energy for long periods of time, i.e. if you're in the near pole regions of a planet, and want to capture solar energy in the summer and use it in the winter, batteries aren't going to work on those timescales. Some other means, generally a stable chemical conversion, will be needed. Converting carbon dioxide to methane or gasoline, converting nitrogen to ammonia (a bit dirty), even converting iron oxide to reduced iron, are all possible methods of doing this. As far as converting atmospheric carbon dioxide to a form that won't eventually get back in the atmosphere, that's pretty difficult (you have to make limestone, CaCO3, or perhaps carbon fiber building materials, or even better, diamond).
aftbit 4y ago
If you are already adding batteries to the train to capture the regenerative breaking energy, why not use that same energy to accelerate again, therefore saving the fossil fuel energy in the diesel generator? Surely that would be more efficient than DAC in a CO2 sense?
- NegativeLatency 4y ago
  Or just go fully electric overhead like they do in northern european countries. Some of the ore trains in the far north generate a fair bit of electricity from regenerative braking that's then used by other trains going uphill or fed into the local power system.
  - cinntaile 4y ago
    These trains in case anyone is wondering. https://en.m.wikipedia.org/wiki/Iore https://en.m.wikipedia.org/wiki/Iore
    - NegativeLatency 4y ago
      Thanks, I was looking for them but couldn't remember the name > From Riksgränsen on the national border to the Port of Narvik, the trains use only a fifth of the power they regenerate. The regenerated energy is sufficient to power the empty trains back up to the national border.
  - sandworm101 4y ago
    The flip side too is that the power generated by a braking train is more likely to be in the voltage range needed by other trains in the system. It is always better the use electricity locally and in the same voltage rather than convert it to grid power.
- tonmoy 4y ago
  Because the motion of the train would alleviate the need for large power consuming fans.
photochemsyn 4y ago
This seems like nonsense on a conservation of energy basis. Putting vents on trains would cost a similar amount of energy as using fans to blow large volumes of air (at ~400 ppm CO2) into carbon-capture systems, and the result would be to slow down the trains and cause them to use more fuel or electricity. Secondly, who is going to pay for this? If CO2 is going to be a valuable commodity itself, then that's because it's going to be used in an industrial process as a feedstock for fuel or material production. In that case, train operators might find this to be an interesting proposition, if the value of the captured CO2 is a good deal higher than the resulting increase in fuel/electricity costs needed to operate these trains. As far as industrial production, this doesn't look good either. It's far easier to just put large atmospheric CO2 capture systems right next to the chemical production system without having to haul trainloads of CO2 all over the place.
thescriptkiddie 4y ago
Trying to put mobile carbon capture systems on diesel trains seems absolutely foolish when electric trains exist. Just put up the damned wires, it will save money in the long run.
adeimantus2001 4y ago
This absolutely reeks of tech grift for the aim of poaching valuable research dollars.
nope96 4y ago
Ah, maybe this is how Snowpiercer drives itself! (A sci-fi show where the only remaining humans live on a train that circles the world, they never explain how the train has infinite fuel.)
- runarberg 4y ago
  If I remember correctly, in the movie it was hinted that the train’s mechanic (Wilford) invented a perpetual motion machine. I’m not sure if the original graphic novel or the TV shows suggests something similar.
Ensorceled 4y ago
> could capture carbon dioxide for less than US $50 a metric ton We currently are emitting 50 BILLION tons per year planet wide. So a mere $2.5 trillion per year to solve the problem? And a lot of trains.
- praestigiare 4y ago
  Net zero for 2.5 trillion a year would be a great deal. We will pay far more than that
  - Ensorceled 4y ago
    Yeah, I was being a bit sarcastic, I don't think $50 a ton is a real number; certainly not an "all expenses in" number. People can't seem to wrap their heads around numbers like 50 billion tons of CO2 ADDED a year.
ryan_j_naughton 4y ago
Regenerative breaking can already exist for trains without adding in the carbon capture [1]. Instead of adding batteries, and thus weight, the train supplies power back to the grid when it breaks. Thus, the cheaper source of energy described here can be achieved without the carbon capture, and consequently, we can use that power to power other things, reducing energy generation overall and reduce CO2 emissions. Thus, it seems like the primary benefit here is using the train's motion to replace the fans required for carbon capture and thus piggybacking on the energy already expended by the train to move. That seems logical, though it could be deployed irrespective of regenerative breaking. Basically we should do regenerative breaking regardless as it is just more energy efficient. Regenerative breaking can primarily be deployed in electric trains anyway as you use the existing motors to break the train, and in so doing, generate electricity from those motors. Adding electric motors and a battery to diesel trains JUST for carbon capture seems foolish. One question I had: how does this carbon capture change the aerodynamics of the train and thus its efficiency? [1] https://www.ctc-n.org/technologies/regenerative-braking-trains#:~:text=Train%20Regenerative%20Braking%20Introduction,reversed%2C%20slowing%20down%20the%20train https://www.ctc-n.org/technologies/regenerative-braking-trai....
- energ8 4y ago
  There might be an additional benefit for fossil fuel trains. Point source capture is usually more efficient than direct air capture. This isn't necessarily directly point source, but if the diesel exhaust is partially directed into the capture train, the CO2 concentration should be higher, and could have a more efficient CO2 capture.
- X6S1x6Okd1st 4y ago
  Do trains always have a connection to the grid?
  - j-pb 4y ago
    Those trains yes, because it's the grid that powers them (through constantly connected overhead lines). There is not really the need to feed that energy back to the grid though, as there are plenty of other trains that are happy to gobble it up.
smm11 4y ago
Snowpiercer
cpdean 4y ago
The thing I hate about this is it continues to belittle the severity of climate change as something that future society will fix for us.
- 2OEH8eoCRo0 4y ago
  Nobody wants to be told to buy fewer goods, ration meat, ration fossil fuels, etc.
  - deleted 4y ago
    [deleted]
- MattGrommes 4y ago
  I always consider things like carbon-capture to be under the category of "We need to do all of the above". Capturing carbon at scale gives us more time to move to renewable energy, which is going to take longer than we have. So we need to do capture, and renewables, and reducing overall energy, and whatever else we can think of. If we had started moving to renewables and electrifying everything 30 years ago, carbon capture wouldn't be needed. But it is needed now.
- midoridensha 4y ago
  The thing I don't like is that people keep acting like we're going to avoid a climate catastrophe. We're not; it's already too late. We might as well get used to the idea that things are going to get really, really bad in the next few decades. The only way to avoid it is to completely stop the things we're doing right now, all over the planet, and that simply isn't going to happen.
guelo 4y ago
Doesn't it make more sense to capture the carbon from the train's diesel engine's tailpipe instead of trying to capture it from the air using fans?
femto 4y ago
Then there are the mining trains that produce net energy: https://www.popularmechanics.com/science/energy/a39372219/self-charging-infinity-train/ https://www.popularmechanics.com/science/energy/a39372219/se... If you're digging iron ore out of a mine and carting it on a one-way trip to the coast the train is always heavier on the way down than the way up. Store the energy from the downwards trip and use it to power the upwards trip, with some left over. Mind you this drives home the reality that mining is a non-renewable resource, as there is no such thing as a perpetual energy source or mine.
twobitshifter 4y ago
I think that is a Rube Goldberg idea. They’ve taken two reasonable ideas, regenerative braking and carbon capture and melded them together on a moving platform where it makes no sense. Some of the problems: 1) The diesel train will emit much more carbon than captured so you are dependent on carbon emissions for your carbon capture. 2) The fans will slow the train speed. 3) The weight of the carbon capture car will increase the train’s load and hence the carbon usage of the train AND it will get heavier as you capture more and more carbon. New diesel passenger trains are able to use regenerative braking to power auxiliary loads (heating cooling &lights), this wouldn’t really work with freight trains unless you were moving something that has to stay refrigerated.

87 points by noplsbecivil 4y ago

After reading this article, I was wondering if a similar approach could be used on cars? Could the braking energy be used in a similar way? What about for trucks?

johnday 4y ago
Surely it is more efficient to store the braking energy in cars for acceleration, which then reduces the amount of fossil fuels burned in the first place? (AIUI this already exists) In fact i'm not sure why that wouldn't also apply to the trains...
- stormbrew 4y ago
  I assume the issue is trains that aren't electric, and I assume even most electric trains don't have significant energy storage on the train itself, so might not really have much to do with energy from breaking. It probably especially makes sense that freight trains running off fossil fuels won't even consume much electricity at all (just enough to operate instruments in the locamotive?), though presumably passenger trains could make use of it. Maybe there are barriers to electrification of some trains in some areas.
  - Glawen 4y ago
    Tramway are regenerating power and injecting them back in the grid when they brake. I think electric trains do it as well, the resistor grid is only used when not enough power in generated
  - pmyteh 4y ago
    Most electric trains only have a small service-and-emergency battery and don't have significant energy storage. For AC electric locomotives it's now standard to return electricity to the grid when using regenerative braking; that's harder with DC electric traction but is done in some circumstances (in others, the generated electricity is dumped into heat via a resistor bank). The main barrier to electrification is the high upfront capital cost of the electrification works, set against the longer-term per-train return in lower fuel and locomotive/multiple unit costs. Lines which are not intensively used are difficult to justify electrifying on a financial-returns basis, and that probably includes most of the world's long-distance freight lines.
  - jimktrains2 4y ago
    Nearly all fossil-fuel burning train engines (I think the exception being a handful of hydraulic engines in Germany?) are diesel-electric, which use the diesel engine to turn an electric generator to power electric traction motors. (Dynamic breaking is when those traction motors are used as generators, but that electricity is usually dissipated as heat immediatly.)
    - jimktrains2 4y ago
      Nearly all non-steam fossil-fuel burning train engines*

elric 4y ago

What's the market for this? Are parts of the US unable to electrify trains for some reason? Surely the easiest way to capture the carbon is not to emit it in the first place, and if you are going to emit it, you might as well do it in a stationary power plant.

fomine3 4y ago
Even if fully electrified train is difficult, hybrid and energy regeneration could be better.
AlgorithmicTime 4y ago
Those ridiculously long distances in the middle of nowhere are not really well suited for overhead electrical wires.
AnimalMuppet 4y ago
> Are parts of the US unable to electrify trains for some reason? It basically comes down to cost. The electric infrastructure costs per mile to install, and per mile per year to maintain. The benefits come per train. If you don't have enough trains per day, it's not economical to electrify. There are some places, like the Union Pacific around North Platte, where you'd think that electrification would be a natural. But the problem is that 90 miles east of North Platte, and 20 miles west of North Platte, the lines split, and the traffic density goes down. Switching between electric and diesel locomotives twice in 110 miles adds operating cost.
- kitten_mittens_ 4y ago
  Even in Boston, the metro transit authority (MBTA) has talked about the options for full electrification of commuter rail costing 18 billion+. https://d2o8eokdkim9o8.cloudfront.net/sites/default/files/2019-10/rail-vision-alternative3-oct2019-accessible.pdf https://d2o8eokdkim9o8.cloudfront.net/sites/default/files/20....
elric 4y ago
Not sure why AlgorithmicTime's comment is dead, so I'll reply here. Long distances are probably tricky to electrify. I don't know enough about US railroads (what little I know of US railroads comes from playing Ticket To Ride) to comment on the feasibility, but there are very long electrified railways in China and Japan, across difficult terrain. There is probably not much benefit in feeding electricity from regenerative braking back onto the overhead line if it's a very long segment with only one train (no one to use the power + transmission losses). I wonder at which point diesel becomes the cleaner option here, if ever. One the one hand, you have to lug a lot of fuel around over longer distances (or you need refueling infrastructure). On the other hand, transmission losses can be significant.

digdugdirk 4y ago

How/why do trains not already recapture the energy created from braking?

AnimalMuppet 4y ago
Electric trains do. For the rest, they don't because of lack of storage. A diesel locomotive has a huge engine block, a generator, a large radiator, and electric motors on the axles. You can turn the motors into generators when you want braking, but where are you going to put the electricity? All the space (and weight) is already used. Yes, they have batteries - enough to crank the engine when it has been turned off. Not enough to run the electric motors on the wheels, though.
- azdle 4y ago
  > but where are you going to put the electricity? Bring back the tender[0], but fill it with batteries instead of coal. Or better yet, intermodal container shaped batteries that could be swapped for pure electric long distance trains. [0] https://en.wikipedia.org/wiki/Tender_(rail) https://en.wikipedia.org/wiki/Tender_(rail)
detaro 4y ago
Modern electric passenger trains do - they can dump power back into the grid, and have enough motors to do a good chunk of braking with them (And e.g. for the German high-speed trains they plan the braking points such that they try to avoid using lossy brakes in normal operation). If you don't have a grid as "storage", you need to carry it, and that's a problem. And freight trains obviously only have motors in the locomotive(s) and do the distributed braking on the cars mechanically, so a good chunk is lost even if the locomotive can do it.
- deleted 4y ago
  [deleted]

ZeroGravitas 4y ago

Trains can be fairly easily electrified (via overhead rails) and hydridized with batteries. Generally they're diesel electric in the first place, so you're just switching electricity source which makes it a smooth transition. So I feel this will lose to batteries, which can be use to brake at every motor, and so can be easily distributed along a train. (Though you don't need batteries for regen braking, you can feed the power back to the grid if you have a connection). And once you have a decent sized battery you can charge from overhead lines when available, which opens up other possibilities. https://www.alstom.com/press-releases-news/2021/9/alstom-presents-its-battery-powered-multiple-unit-train-saxony https://www.alstom.com/press-releases-news/2021/9/alstom-pre... > The studies have revealed, for example, that a large proportion of the lines currently operated with diesel vehicles include non-electrified sections of well under 60 miles. The use of the existing catenary infrastructure allows battery-powered electric vehicles to be operated on these lines without major upgrades to the existing infrastructure. Extensive travel dynamics and energy simulations were also carried out as part of the project. A similarly wacky concept, that I perhaps like is shipping full batteries to places where energy is expensive via train. So charge up a train battery from solar as it travels east, then feed that back to the grid as you meet a post sunset peak. Possibly wouldn't make sense if you were to do it for it's own sake, but if you already have a network of battery trains that can time their charge, you can probably save a reasonable amount of money by optimising when/where you charge based on time of use and demand response events. Coordinated Demand Response of Rail Transit Load and Energy Storage System Considering Driving Comfort https://www.researchgate.net/publication/347975248_Coordinated_Demand_Response_of_Rail_Transit_Load_and_Energy_Storage_System_Considering_Driving_Comfort https://www.researchgate.net/publication/347975248_Coordinat...

lstodd 4y ago
Batteries are no-go. Typical electric locomotive is like 5MW sustained for multiple hours. It wouldn't be able to pull just its own batteries for any reasonable distance. 60 miles of catenary is way cheaper than wasting energy pulling dead weight that batteries are.
- ZeroGravitas 4y ago

mdavis6890 4y ago

I still do not understand how any human-developed carbon capture techniques is going to be better or more efficient than just planting a tree. A (living, growing) tree can capture quite a lot of carbon for almost no cost, directly from the atmosphere. More generally, vegetation biomass growth is carbon (and hydrogen) capture in action on planetary scale - almost for free.

TremendousJudge 4y ago
Or at least create the hydrocarbons in a factory, sucking the carbon from the atmosphere, and using energy from renewable sources or something of the sort. This would be carbon neutral at least, and still allows liquid fuels to be used. I have never seen anybody invest into this research. Somebody please correct me if I'm mistaken here.
- noplsbecivil 4y ago
  Not quite there yet, but https://solugen.com/ https://solugen.com/ are trying
L_226 4y ago
Because trees cannot be grown just anywhere, they require specific [land, water, nutrient] conditions that also happen to be the same things that are already under pressure from our civilisation. This is caused by things like extensive monocrop agriculture, grazing etc. Furthermore, trees do not necessarily sequester carbon beyond their lifespan - the sequestration is an additional process that may or may not occur naturally. Think of old trees dying, falling down and decomposing vs old trees dying and being covered by mud.
ch4s3 4y ago
Photosynthesis is pretty inefficient and trees release the CO2 when they rot, so they aren’t great for long term storage. At certain phases of growth, forests are actually carbon positive. DAC can bind carbon to rock or pump it deep underground where it will stay potentially forever(on any meaningful human timescale). You can also directly account for the tons of CO2 removed by DAC which makes it more used for carbon trading schemes that financially incentivize capture.

TremendousJudge 4y ago

I really don't understand how carbon capture can make sense, in terms of thermodynamics. Burning hydrocarbons releases energy, plus carbon dioxide and water vapor. Capturing the carbon dioxide back would, in some way, require an equivalent amount of energy to be spent, right? Where is this energy coming from? In this case, it's actually mentioned in the article (unlike many other carbon capture proposals): add regenerative braking to trains -- plus make the engines work harder by adding a lot of extra air resistance for the filtering system. Meanwhile, the European electric grid -- and therefore its electric trains -- is partly ran by burning fossil fuels (not to mention the manufacturing processes for the proposed batteries and filters). So you're burning carbon in order to get carbon out of the atmosphere -- there's no way that equation comes out as a net negative for emissions, there are inefficiencies everywhere. This is honestly one of the most compelling carbon capture proposals I have read, and it still doesn't make sense to me. What am I missing here? Why is this being taken seriously?

kitkat_new 4y ago
the energy is coming from the sun. And you are right... even worse: putting carbon emitted back into the ground requires not only the energy gained through burning, but several multitudes of that. That's why not burning it in the first place is almost always better. Still, carbon capture is necessary, because there are things that are extremely hard to substitute. Further, if we don't go for negative emissions, we will have at least 4 degrees of warming (even if we stop emitting now). Just watch out for greenwashing
photochemsyn 4y ago
Artificial photosynthesis is absolutely required in several sectors, if you want to eliminate the use of fossil fuels. International air travel is the main example, so is space travel, and global shipping is a little behind. There's no way to fly passenger jets over the Atlantic and Pacific Ocean using battery power; the density is just too low. Likewise, if you want to have SpaceX continue to launch large methane-fueled or RP-1 fueled rockets without fossil fuels, capture of atmospheric CO2 and conversion to hydrocarbon fuel will be needed. It's also a way of storing energy for long periods of time, i.e. if you're in the near pole regions of a planet, and want to capture solar energy in the summer and use it in the winter, batteries aren't going to work on those timescales. Some other means, generally a stable chemical conversion, will be needed. Converting carbon dioxide to methane or gasoline, converting nitrogen to ammonia (a bit dirty), even converting iron oxide to reduced iron, are all possible methods of doing this. As far as converting atmospheric carbon dioxide to a form that won't eventually get back in the atmosphere, that's pretty difficult (you have to make limestone, CaCO3, or perhaps carbon fiber building materials, or even better, diamond).

aftbit 4y ago

If you are already adding batteries to the train to capture the regenerative breaking energy, why not use that same energy to accelerate again, therefore saving the fossil fuel energy in the diesel generator? Surely that would be more efficient than DAC in a CO2 sense?

NegativeLatency 4y ago
Or just go fully electric overhead like they do in northern european countries. Some of the ore trains in the far north generate a fair bit of electricity from regenerative braking that's then used by other trains going uphill or fed into the local power system.
- cinntaile 4y ago
  These trains in case anyone is wondering. https://en.m.wikipedia.org/wiki/Iore https://en.m.wikipedia.org/wiki/Iore
  - NegativeLatency 4y ago
    Thanks, I was looking for them but couldn't remember the name > From Riksgränsen on the national border to the Port of Narvik, the trains use only a fifth of the power they regenerate. The regenerated energy is sufficient to power the empty trains back up to the national border.
- sandworm101 4y ago
  The flip side too is that the power generated by a braking train is more likely to be in the voltage range needed by other trains in the system. It is always better the use electricity locally and in the same voltage rather than convert it to grid power.
tonmoy 4y ago
Because the motion of the train would alleviate the need for large power consuming fans.

photochemsyn 4y ago

This seems like nonsense on a conservation of energy basis. Putting vents on trains would cost a similar amount of energy as using fans to blow large volumes of air (at ~400 ppm CO2) into carbon-capture systems, and the result would be to slow down the trains and cause them to use more fuel or electricity. Secondly, who is going to pay for this? If CO2 is going to be a valuable commodity itself, then that's because it's going to be used in an industrial process as a feedstock for fuel or material production. In that case, train operators might find this to be an interesting proposition, if the value of the captured CO2 is a good deal higher than the resulting increase in fuel/electricity costs needed to operate these trains. As far as industrial production, this doesn't look good either. It's far easier to just put large atmospheric CO2 capture systems right next to the chemical production system without having to haul trainloads of CO2 all over the place.

thescriptkiddie 4y ago

Trying to put mobile carbon capture systems on diesel trains seems absolutely foolish when electric trains exist. Just put up the damned wires, it will save money in the long run.

adeimantus2001 4y ago

This absolutely reeks of tech grift for the aim of poaching valuable research dollars.

nope96 4y ago

Ah, maybe this is how Snowpiercer drives itself! (A sci-fi show where the only remaining humans live on a train that circles the world, they never explain how the train has infinite fuel.)

runarberg 4y ago
If I remember correctly, in the movie it was hinted that the train’s mechanic (Wilford) invented a perpetual motion machine. I’m not sure if the original graphic novel or the TV shows suggests something similar.

Ensorceled 4y ago

> could capture carbon dioxide for less than US $50 a metric ton We currently are emitting 50 BILLION tons per year planet wide. So a mere $2.5 trillion per year to solve the problem? And a lot of trains.

praestigiare 4y ago
Net zero for 2.5 trillion a year would be a great deal. We will pay far more than that
- Ensorceled 4y ago
  Yeah, I was being a bit sarcastic, I don't think $50 a ton is a real number; certainly not an "all expenses in" number. People can't seem to wrap their heads around numbers like 50 billion tons of CO2 ADDED a year.

ryan_j_naughton 4y ago

Regenerative breaking can already exist for trains without adding in the carbon capture [1]. Instead of adding batteries, and thus weight, the train supplies power back to the grid when it breaks. Thus, the cheaper source of energy described here can be achieved without the carbon capture, and consequently, we can use that power to power other things, reducing energy generation overall and reduce CO2 emissions. Thus, it seems like the primary benefit here is using the train's motion to replace the fans required for carbon capture and thus piggybacking on the energy already expended by the train to move. That seems logical, though it could be deployed irrespective of regenerative breaking. Basically we should do regenerative breaking regardless as it is just more energy efficient. Regenerative breaking can primarily be deployed in electric trains anyway as you use the existing motors to break the train, and in so doing, generate electricity from those motors. Adding electric motors and a battery to diesel trains JUST for carbon capture seems foolish. One question I had: how does this carbon capture change the aerodynamics of the train and thus its efficiency? [1] https://www.ctc-n.org/technologies/regenerative-braking-trains#:~:text=Train%20Regenerative%20Braking%20Introduction,reversed%2C%20slowing%20down%20the%20train https://www.ctc-n.org/technologies/regenerative-braking-trai....

energ8 4y ago
There might be an additional benefit for fossil fuel trains. Point source capture is usually more efficient than direct air capture. This isn't necessarily directly point source, but if the diesel exhaust is partially directed into the capture train, the CO2 concentration should be higher, and could have a more efficient CO2 capture.
X6S1x6Okd1st 4y ago
Do trains always have a connection to the grid?
- j-pb 4y ago
  Those trains yes, because it's the grid that powers them (through constantly connected overhead lines). There is not really the need to feed that energy back to the grid though, as there are plenty of other trains that are happy to gobble it up.

smm11 4y ago

Snowpiercer

cpdean 4y ago

The thing I hate about this is it continues to belittle the severity of climate change as something that future society will fix for us.

2OEH8eoCRo0 4y ago
Nobody wants to be told to buy fewer goods, ration meat, ration fossil fuels, etc.
- deleted 4y ago
  [deleted]
MattGrommes 4y ago
I always consider things like carbon-capture to be under the category of "We need to do all of the above". Capturing carbon at scale gives us more time to move to renewable energy, which is going to take longer than we have. So we need to do capture, and renewables, and reducing overall energy, and whatever else we can think of. If we had started moving to renewables and electrifying everything 30 years ago, carbon capture wouldn't be needed. But it is needed now.
midoridensha 4y ago
The thing I don't like is that people keep acting like we're going to avoid a climate catastrophe. We're not; it's already too late. We might as well get used to the idea that things are going to get really, really bad in the next few decades. The only way to avoid it is to completely stop the things we're doing right now, all over the planet, and that simply isn't going to happen.

guelo 4y ago

Doesn't it make more sense to capture the carbon from the train's diesel engine's tailpipe instead of trying to capture it from the air using fans?

femto 4y ago

Then there are the mining trains that produce net energy: https://www.popularmechanics.com/science/energy/a39372219/self-charging-infinity-train/ https://www.popularmechanics.com/science/energy/a39372219/se... If you're digging iron ore out of a mine and carting it on a one-way trip to the coast the train is always heavier on the way down than the way up. Store the energy from the downwards trip and use it to power the upwards trip, with some left over. Mind you this drives home the reality that mining is a non-renewable resource, as there is no such thing as a perpetual energy source or mine.

twobitshifter 4y ago

I think that is a Rube Goldberg idea. They’ve taken two reasonable ideas, regenerative braking and carbon capture and melded them together on a moving platform where it makes no sense. Some of the problems: 1) The diesel train will emit much more carbon than captured so you are dependent on carbon emissions for your carbon capture. 2) The fans will slow the train speed. 3) The weight of the carbon capture car will increase the train’s load and hence the carbon usage of the train AND it will get heavier as you capture more and more carbon. New diesel passenger trains are able to use regenerative braking to power auxiliary loads (heating cooling &lights), this wouldn’t really work with freight trains unless you were moving something that has to stay refrigerated.