5 ms·

Most commercial trucks are lacking for weight, not for volume. They wouldn't use all those axles and tires if they didn't need to. Weight and charging time ar

Most commercial trucks are lacking for weight, not for volume. They wouldn't use all those axles and tires if they didn't need to. Weight and charging time are the current major roadblocks to adopting batteries. Hydrogen theoretically solves those but introduces a lot of technical complexity along the way and needs a supply chain that currently doesn't exist.

SigmundA 6y ago
I don't see a lot of extra room on a truck for safe liquid hydrogen tanks 5 times the size of diesel tanks.
- darksaints 6y ago
  That would be true for cars, not so much for trucks. Most trucks hit their mass limits long before they hit their volume limits. Most box trucks, for example, are transporting more air by volume than cargo.
  - SigmundA 6y ago
    Trucks have length limits and more constrained in Europe which is why you still see many cab overs there. The US loosened length limits in the 70's allowing for long nose trucks which help with aero dynamics and safety.
    - darksaints 6y ago
      So you don't store it on the tractor itself, you store it with the trailer. That's how your god Elon is proposing to do it with batteries.
      - SigmundA 6y ago
        Yes with 10,000 psi hydrogen lines from trailer to tractor and expensive tanks on the trailer. AFAIK the Tesla semi has all batteries in the tractor. He is most certainly not my god.
        darksaints 6y ago
        The Tesla semi, without batteries on the trailer, is limited to about 500kWh of batteries...maybe 1000kWh if you have some extremely clever engineering. You can't really do much more than that without moving to a monocoque carbon frame to offset the weight, because the batteries are too dense. Commercial trucks have total weight limits, but they also have per-axle weight limits. If you are too heavy on a single axle, you're illegal. And while 500kWh batteries, are awesome and the perfect use case for local delivery, they won't cut it for OTR trucking. You need 700 mi of range at an absolute minimum for singles, ~2000mi for doubles. The weight of a 700 mile battery is a non-starter. Tesla's largest battery pack that they're even considering selling has a 500 mi range. There is a reason Tesla quotes kWh/mile, and not kWh/lb-mi (cargo, not GVW). They aren't competitive, and they likely never will be. And adding more batteries just makes the economics less competitive. There's a saying in the aircraft industry: it takes a lot of fuel to fly a lot of fuel. The same goes for batteries: it takes a lot of battery to move a lot of battery. Batteries, no matter what technical advances can be made, have limitations posed by the laws of physics, and none of them will ever have the energy density to make sense for long haul trucking. Which is why actual trucking companies that have actually beat His Lord and Savior Elon Musk to market with electric trucks (i.e. Volvo) are still looking to better alternatives in the long run.
        SigmundA 6y ago
        So now how much does a hydrogen fuel cell semi weigh whats its range? How much does it cost? Where do you fill it up? Current hydrogen fuel cell vehicles weight more than an equivalent battery powered car not not even looking at cost and power and refueling infrastructure. I agree that diesel is most viable for long haul and probably will be for some time and still has room to improve see Frieghtliners SuperTruck.
        darksaints 6y ago
        Fuel cell technology used in cars is inferior to battery technology cars. But it's not comparable here. A light, intermittently used vehicle, with fast startup and frequent shutoff, and with no long range requirements, does not have the same set of constraints that class 8 trucks do. Holy Father Elon's criticism of fuel cells in passenger vehicles do not apply here at all. 800hp fuel cell: 500-600lbs, 3 cubic feet. 60% efficiency baseline, easily augmented to 75% with heat recovery. https://technology.nasa.gov/patent/LEW-TOPS-120 https://technology.nasa.gov/patent/LEW-TOPS-120 Runs on any hydrogen-based fuel: pure hydrogen, methane, butane, propane, gasoline, avgas, diesel, ammonia, whatever. In fact, you can mix fuels in the same tank, and the SOFC will consume them regardless. Use any infrastructure that you want. Use any fuel system that you want. You can start out running standard low-sulfur diesel, or use natural gas or propane with standard modifications that are already used for diesel conversions all over the third world. If hydrogen storage works out for your use case, then use it. If it doesn't, then just use diesel and wait for synthetic fuels to drop in price. There will never be a battery-powered truck that can compete with that value proposition for long haul trucking.
    - JoblessWonder 6y ago
      Thanks for explaining why Europe has mostly cab overs.... I noticed it but never bothered to figure out why!
- maxerickson 6y ago
  Split trucks have lots of room. https://m.youtube.com/watch?v=4Bk7-L7ffiY https://m.youtube.com/watch?v=4Bk7-L7ffiY
  - SigmundA 6y ago
    Long wheelbase sleepers are very difficult to maneuver, they are pretty specialized and you won't see them in Europe do to length restrictions.
    - maxerickson 6y ago
      Sure, but it's an absurd example of space not being a particularly critical factor. That thing is a huge factor bigger than the volume of the fuel tanks.
      - SigmundA 6y ago
        Not sure why you say that, its very critical in Europe and still a concern in the US.
marcosdumay 6y ago
The problem with all those calculations is that storing hydrogen requires a lot of weight. If hydrogen were such a great idea, trucks would be already migrating to the in-between solution that is natural gas.
- thehappypm 6y ago
  Trucks maybe aren't, but city buses certainly are, all over the country. That's likely because of the infrastructure. You don't need to dot the entire country with LNG stops for your city buses, just a few fuel-up points here and there around town.
  - marcosdumay 6y ago
    Yes, buses and taxis are big adopters of it. Maybe there is something there and if we cut the cost of hydrogen enough (you know, all that extra solar power must go somewhere), it will be interesting for them too.
- albrewer 6y ago
  I second this insight. I'm a pressure vessel designer by trade. I got my numbers for all of this here[0] Liquefied hydrogen either needs to be stored cryogenically as a liquid, or at a very high pressure as a gas (65 MPa). I'm ignoring adsorption methods here. Given that we can't continuously maintain -253 °C all the time, this method is impractical for mobile usage. That leaves gaseous storage. To match the current range of diesel tractor-trailers, you'd need at least 4x the volume in hydrogen to come close to the standard of 600 miles between refills. I'm going to assume we need to store 1500 L of hydrogen to match the range. Other assumptions: The tank has a max overall length of roughly 2.5 meters. Inner and outer corrosion / gouge allowance of 6mm Design temperature of 200 °C (in case of fire). Material of construction is A-387 5 2 (5% Cr, 2% Mo steel) lined with something that prevents diffusion into and hydrogen embrittlement of the base metal. Vessel consists of a cylinder with spherical head on either end. Given: Inner diameter is 890mm, shell length is 1830mm, allowable stress is 178 MPa at the design temperature, we can use equation 4.3.1 from the ASME BPVC Section VIII Division 2 to determine the minimum thickness required for the given pressure. D is the corroded inner diameter of the vessel, P is the design pressure, S is the allowable stress, and E is the weld joint efficiency (assumed 1). D / 2 * (exp[P / (S * E)] - 1) + Corrosion 902 / 2 * (exp[65 / (178 * 1)] - 1) + 12 = 211mm wall thickness The weight of just the cylinder at that thickness with a length of 1.83m (without the spherical heads) is 11,000 kg. At that weight, batteries are pretty competitive. [0]: https://www.energy.gov/eere/fuelcells/hydrogen-storage-basics-0 https://www.energy.gov/eere/fuelcells/hydrogen-storage-basic...

SigmundA 6y ago

I don't see a lot of extra room on a truck for safe liquid hydrogen tanks 5 times the size of diesel tanks.

darksaints 6y ago
That would be true for cars, not so much for trucks. Most trucks hit their mass limits long before they hit their volume limits. Most box trucks, for example, are transporting more air by volume than cargo.
- SigmundA 6y ago
  Trucks have length limits and more constrained in Europe which is why you still see many cab overs there. The US loosened length limits in the 70's allowing for long nose trucks which help with aero dynamics and safety.
  - darksaints 6y ago
    So you don't store it on the tractor itself, you store it with the trailer. That's how your god Elon is proposing to do it with batteries.
    - SigmundA 6y ago
      Yes with 10,000 psi hydrogen lines from trailer to tractor and expensive tanks on the trailer. AFAIK the Tesla semi has all batteries in the tractor. He is most certainly not my god.
      - darksaints 6y ago
        The Tesla semi, without batteries on the trailer, is limited to about 500kWh of batteries...maybe 1000kWh if you have some extremely clever engineering. You can't really do much more than that without moving to a monocoque carbon frame to offset the weight, because the batteries are too dense. Commercial trucks have total weight limits, but they also have per-axle weight limits. If you are too heavy on a single axle, you're illegal. And while 500kWh batteries, are awesome and the perfect use case for local delivery, they won't cut it for OTR trucking. You need 700 mi of range at an absolute minimum for singles, ~2000mi for doubles. The weight of a 700 mile battery is a non-starter. Tesla's largest battery pack that they're even considering selling has a 500 mi range. There is a reason Tesla quotes kWh/mile, and not kWh/lb-mi (cargo, not GVW). They aren't competitive, and they likely never will be. And adding more batteries just makes the economics less competitive. There's a saying in the aircraft industry: it takes a lot of fuel to fly a lot of fuel. The same goes for batteries: it takes a lot of battery to move a lot of battery. Batteries, no matter what technical advances can be made, have limitations posed by the laws of physics, and none of them will ever have the energy density to make sense for long haul trucking. Which is why actual trucking companies that have actually beat His Lord and Savior Elon Musk to market with electric trucks (i.e. Volvo) are still looking to better alternatives in the long run.
        SigmundA 6y ago
        So now how much does a hydrogen fuel cell semi weigh whats its range? How much does it cost? Where do you fill it up? Current hydrogen fuel cell vehicles weight more than an equivalent battery powered car not not even looking at cost and power and refueling infrastructure. I agree that diesel is most viable for long haul and probably will be for some time and still has room to improve see Frieghtliners SuperTruck.
        darksaints 6y ago
        Fuel cell technology used in cars is inferior to battery technology cars. But it's not comparable here. A light, intermittently used vehicle, with fast startup and frequent shutoff, and with no long range requirements, does not have the same set of constraints that class 8 trucks do. Holy Father Elon's criticism of fuel cells in passenger vehicles do not apply here at all. 800hp fuel cell: 500-600lbs, 3 cubic feet. 60% efficiency baseline, easily augmented to 75% with heat recovery. https://technology.nasa.gov/patent/LEW-TOPS-120 https://technology.nasa.gov/patent/LEW-TOPS-120 Runs on any hydrogen-based fuel: pure hydrogen, methane, butane, propane, gasoline, avgas, diesel, ammonia, whatever. In fact, you can mix fuels in the same tank, and the SOFC will consume them regardless. Use any infrastructure that you want. Use any fuel system that you want. You can start out running standard low-sulfur diesel, or use natural gas or propane with standard modifications that are already used for diesel conversions all over the third world. If hydrogen storage works out for your use case, then use it. If it doesn't, then just use diesel and wait for synthetic fuels to drop in price. There will never be a battery-powered truck that can compete with that value proposition for long haul trucking.
  - JoblessWonder 6y ago
    Thanks for explaining why Europe has mostly cab overs.... I noticed it but never bothered to figure out why!
maxerickson 6y ago
Split trucks have lots of room. https://m.youtube.com/watch?v=4Bk7-L7ffiY https://m.youtube.com/watch?v=4Bk7-L7ffiY
- SigmundA 6y ago
  Long wheelbase sleepers are very difficult to maneuver, they are pretty specialized and you won't see them in Europe do to length restrictions.
  - maxerickson 6y ago
    Sure, but it's an absurd example of space not being a particularly critical factor. That thing is a huge factor bigger than the volume of the fuel tanks.
    - SigmundA 6y ago
      Not sure why you say that, its very critical in Europe and still a concern in the US.

marcosdumay 6y ago

The problem with all those calculations is that storing hydrogen requires a lot of weight. If hydrogen were such a great idea, trucks would be already migrating to the in-between solution that is natural gas.

thehappypm 6y ago
Trucks maybe aren't, but city buses certainly are, all over the country. That's likely because of the infrastructure. You don't need to dot the entire country with LNG stops for your city buses, just a few fuel-up points here and there around town.
- marcosdumay 6y ago
  Yes, buses and taxis are big adopters of it. Maybe there is something there and if we cut the cost of hydrogen enough (you know, all that extra solar power must go somewhere), it will be interesting for them too.
albrewer 6y ago
I second this insight. I'm a pressure vessel designer by trade. I got my numbers for all of this here[0] Liquefied hydrogen either needs to be stored cryogenically as a liquid, or at a very high pressure as a gas (65 MPa). I'm ignoring adsorption methods here. Given that we can't continuously maintain -253 °C all the time, this method is impractical for mobile usage. That leaves gaseous storage. To match the current range of diesel tractor-trailers, you'd need at least 4x the volume in hydrogen to come close to the standard of 600 miles between refills. I'm going to assume we need to store 1500 L of hydrogen to match the range. Other assumptions: The tank has a max overall length of roughly 2.5 meters. Inner and outer corrosion / gouge allowance of 6mm Design temperature of 200 °C (in case of fire). Material of construction is A-387 5 2 (5% Cr, 2% Mo steel) lined with something that prevents diffusion into and hydrogen embrittlement of the base metal. Vessel consists of a cylinder with spherical head on either end. Given: Inner diameter is 890mm, shell length is 1830mm, allowable stress is 178 MPa at the design temperature, we can use equation 4.3.1 from the ASME BPVC Section VIII Division 2 to determine the minimum thickness required for the given pressure. D is the corroded inner diameter of the vessel, P is the design pressure, S is the allowable stress, and E is the weld joint efficiency (assumed 1). D / 2 * (exp[P / (S * E)] - 1) + Corrosion 902 / 2 * (exp[65 / (178 * 1)] - 1) + 12 = 211mm wall thickness The weight of just the cylinder at that thickness with a length of 1.83m (without the spherical heads) is 11,000 kg. At that weight, batteries are pretty competitive. [0]: https://www.energy.gov/eere/fuelcells/hydrogen-storage-basics-0 https://www.energy.gov/eere/fuelcells/hydrogen-storage-basic...