5 ms·

I'd guess the one important application of fuel cell tech that people often appear to forget is going to be long haul trucks where it'll replace the diesel powe

by ephbit 4y ago

I'd guess the one important application of fuel cell tech that people often appear to forget is going to be long haul trucks where it'll replace the diesel power train. It's a big chunk of overall land transport that IMO in the long-term won't have other technologically/economically viable options besides the fuel cell. Rail doesn't serve the last few miles to the destination. Electric trucks are viable for short distances. Trucking dozens of tons of cargo over distances > 500 miles isn't going to roll well with carrying another 3-5 tons of battery. And having to recharge that at 2 MW every now and then would require a very reliable/available and ubiquitous high power charging infrastructure.

vardump 4y ago
I think about 2 ton battery is closer to truth for a truck that has about 400-500 mile range. Less, if you consider all the heavy diesel engine and transmission parts an electric truck is not going to need. Charging at the starting point while loading, at (mandatory) breaks and at the destination should be enough; a BEV truck done right shouldn't require extra waiting time.
- lazide 4y ago
  That ignores all the existing infra (or lack thereof). Fossil fuels are very energy dense, and we still have tons of truck stops everywhere - and need them! Last mile, most dropoffs are not going to have power infra to allow MW+ Charging of every truck that shows up, at least not without a lot of time to upgrade. And many won’t want to even try, as they’re paying the logistics companies so they don’t need to deal with stuff like that. Even distribution centers would struggle (capex wise), as we’d be talking 100s of megawatts at least of extra load, possibly giggawatts.
  - TEP_Kim_Il_Sung 4y ago
    Hybrid trucks make more sense: Just use a diesel APU to keep your batteries topped off, as has been the practice with trains since the 1800s
    - lazide 4y ago
      The question though, is why? I’m struggling to see a significant enough economic advantage with the ways trucks are used that would offset the larger capex and complexity. Diesel locomotives don’t use batteries, and have a very different load/power pattern
      - TEP_Kim_Il_Sung 4y ago
        Hybrid trucks make more sense than electric trucks, but diesel trucks make the most sense, is all I meant.
        lazide 4y ago
        Thanks for clarifying, I totally misunderstood your point.
- ephbit 4y ago
  > I think about 2 ton battery is closer to truth for a truck that has about 400-500 mile range. A Tesla Model 3 has a ~ 500 kg battery and weighs ~ 2 tons. With the drag coefficient of a truck being significantly greater and its gross weight amounting to ~ 15-20 times that of the Model 3, I'd say your 2 tons are way off. Sure, the truck will go slower than the Model 3, but still. Also electric motors do weigh a few kg's as well, so I'd guess the less heavy drive train of the electric vehicle isn't going to save all that much weight. > Charging at the starting point while loading, at (mandatory) breaks and at the destination should be enough; a BEV truck done right shouldn't require extra waiting time. I think this needs to be compared to the procedure with a diesel truck. The diesel truck needs a few minutes at the gas station to refill and get some Ad Blue or what. Then it's all flexible to go anywhere for a few hundred miles. Compared to that, your BEV truck is going to need careful planning ahead of charging and any small deviation from the plan is going to be a lot more of a hassle than for the diesel truck. Point being. Nope, there aren't many H2 gas stations either as of now. But once there are, the refuelling of a FCEV will be much more similar to that of a diesel/gasoline vehicle than that of a BEV, aka more convenient/resilient.
  - vardump 4y ago
    "A Tesla Model 3 has a ~ 500 kg battery and weighs ~ 2 tons. With the drag coefficient of a truck being significantly greater and its gross weight amounting to ~ 15-20 times that of the Model 3, I'd say your 2 tons are way off. Sure, the truck will go slower than the Model 3, but still." A truck should consume about 5x than what a Model 3 LR does. 5x 445 kg (actual M3LR battery weight) is 2225 kg.
    - ephbit 4y ago
      > A truck should consume about 5x than what a Model 3 LR does. Do you have any hints as to why "5x" should be roughly correct?
    - ephbit 4y ago
      Model 3 Cd: ~ 0.23 [1] Tesla Semi Cd: ~ 0.36 [2] A shipping container measures w x h: 2.438 x 2.591 m The total height of the truck will be > 3 m so we're talking about 2.438 m x 3 m projected area. That's ~ 7.3 m2 A Tesla S apparently has 0.562 m2 drag area so let's assume 0.6 m2 for the Model 3. [1] This amounts to a factor of Semi to Model 3 of: 7.3 m2 * 0.36 / (0.6 m2 * 0.23) = 19 So at the same speed the aerodynamic drag of a truck will be almost 20 times that of a Model 3. Yes, a truck typically drives slower and speed goes into calculation of engine power at a power of 3. But the truck would have to go slower than the Model 3 by a factor of 19^(1/3) ~ 2.7 to have roughly the same drag. If the Model 3 drives at 150 kph and the Semi at 100 kph, the Semi still has more than 5 times the aerodynamic drag. And you'll have to add friction to that and losses for accelerating the greater mass. (I doubt regenerative braking will scale well with increased vehicle mass) [1] https://en.wikipedia.org/wiki/Automobile_drag_coefficient https://en.wikipedia.org/wiki/Automobile_drag_coefficient [2] https://insideevs.com/news/345710/tesla-semi-details-on-truck-aerodynamics-and-drag-coefficient/ https://insideevs.com/news/345710/tesla-semi-details-on-truc...

by ephbit 4y ago

vardump 4y ago

I think about 2 ton battery is closer to truth for a truck that has about 400-500 mile range. Less, if you consider all the heavy diesel engine and transmission parts an electric truck is not going to need. Charging at the starting point while loading, at (mandatory) breaks and at the destination should be enough; a BEV truck done right shouldn't require extra waiting time.

lazide 4y ago
That ignores all the existing infra (or lack thereof). Fossil fuels are very energy dense, and we still have tons of truck stops everywhere - and need them! Last mile, most dropoffs are not going to have power infra to allow MW+ Charging of every truck that shows up, at least not without a lot of time to upgrade. And many won’t want to even try, as they’re paying the logistics companies so they don’t need to deal with stuff like that. Even distribution centers would struggle (capex wise), as we’d be talking 100s of megawatts at least of extra load, possibly giggawatts.
- TEP_Kim_Il_Sung 4y ago
  Hybrid trucks make more sense: Just use a diesel APU to keep your batteries topped off, as has been the practice with trains since the 1800s
  - lazide 4y ago
    The question though, is why? I’m struggling to see a significant enough economic advantage with the ways trucks are used that would offset the larger capex and complexity. Diesel locomotives don’t use batteries, and have a very different load/power pattern
    - TEP_Kim_Il_Sung 4y ago
      Hybrid trucks make more sense than electric trucks, but diesel trucks make the most sense, is all I meant.
      - lazide 4y ago
        Thanks for clarifying, I totally misunderstood your point.
ephbit 4y ago
> I think about 2 ton battery is closer to truth for a truck that has about 400-500 mile range. A Tesla Model 3 has a ~ 500 kg battery and weighs ~ 2 tons. With the drag coefficient of a truck being significantly greater and its gross weight amounting to ~ 15-20 times that of the Model 3, I'd say your 2 tons are way off. Sure, the truck will go slower than the Model 3, but still. Also electric motors do weigh a few kg's as well, so I'd guess the less heavy drive train of the electric vehicle isn't going to save all that much weight. > Charging at the starting point while loading, at (mandatory) breaks and at the destination should be enough; a BEV truck done right shouldn't require extra waiting time. I think this needs to be compared to the procedure with a diesel truck. The diesel truck needs a few minutes at the gas station to refill and get some Ad Blue or what. Then it's all flexible to go anywhere for a few hundred miles. Compared to that, your BEV truck is going to need careful planning ahead of charging and any small deviation from the plan is going to be a lot more of a hassle than for the diesel truck. Point being. Nope, there aren't many H2 gas stations either as of now. But once there are, the refuelling of a FCEV will be much more similar to that of a diesel/gasoline vehicle than that of a BEV, aka more convenient/resilient.
- vardump 4y ago
  "A Tesla Model 3 has a ~ 500 kg battery and weighs ~ 2 tons. With the drag coefficient of a truck being significantly greater and its gross weight amounting to ~ 15-20 times that of the Model 3, I'd say your 2 tons are way off. Sure, the truck will go slower than the Model 3, but still." A truck should consume about 5x than what a Model 3 LR does. 5x 445 kg (actual M3LR battery weight) is 2225 kg.
  - ephbit 4y ago
    > A truck should consume about 5x than what a Model 3 LR does. Do you have any hints as to why "5x" should be roughly correct?
  - ephbit 4y ago
    Model 3 Cd: ~ 0.23 [1] Tesla Semi Cd: ~ 0.36 [2] A shipping container measures w x h: 2.438 x 2.591 m The total height of the truck will be > 3 m so we're talking about 2.438 m x 3 m projected area. That's ~ 7.3 m2 A Tesla S apparently has 0.562 m2 drag area so let's assume 0.6 m2 for the Model 3. [1] This amounts to a factor of Semi to Model 3 of: 7.3 m2 * 0.36 / (0.6 m2 * 0.23) = 19 So at the same speed the aerodynamic drag of a truck will be almost 20 times that of a Model 3. Yes, a truck typically drives slower and speed goes into calculation of engine power at a power of 3. But the truck would have to go slower than the Model 3 by a factor of 19^(1/3) ~ 2.7 to have roughly the same drag. If the Model 3 drives at 150 kph and the Semi at 100 kph, the Semi still has more than 5 times the aerodynamic drag. And you'll have to add friction to that and losses for accelerating the greater mass. (I doubt regenerative braking will scale well with increased vehicle mass) [1] https://en.wikipedia.org/wiki/Automobile_drag_coefficient https://en.wikipedia.org/wiki/Automobile_drag_coefficient [2] https://insideevs.com/news/345710/tesla-semi-details-on-truck-aerodynamics-and-drag-coefficient/ https://insideevs.com/news/345710/tesla-semi-details-on-truc...