6 ms·

It depends on how you define convenient. Hydrogen can be refilled quickly, in minutes, like a conventional liquid fueled car. If there were a network of hydroge

It depends on how you define convenient. Hydrogen can be refilled quickly, in minutes, like a conventional liquid fueled car. If there were a network of hydrogen filling stations then driving, especially long distances, would be similar to driving a liquid fueled car.

Cthulhu_ 5y ago
More like an electric car, if it's a hydrogen fuel cell car (I'm not sure if all hydrogen cars are that or if there's another variant that combusts the hydrogen)
- jdblair 5y ago
  Drives like an electric, refuels like a liquid fuel car (it uses a compressor, not electric charge).
  - bryanlarsen 5y ago
    If by "electric" you mean "Prius", you're right. Tesla's and similar cars have great acceleration because they support massive currents at high voltages. They need this to support fast charging, the incremental cost of adding a high torque motor is small. Hydrogen cars have tiny batteries that don't need to support fast charging. Like a Prius.
    - hwillis 5y ago
      > Hydrogen cars have tiny batteries that don't need to support fast charging. Because that's what they think consumers want, not because of technological limitations. Size is not a requirement for high power batteries. The Porsche 918 has a 6.8 kWh battery that can do 210 kW. That's ~31 kW per kWh, compared to a top-end Model S at ~6 kW/kWh.
      - bryanlarsen 5y ago
        Yes, a $800K Hydrogen car would probably have a small but high power battery. But Nexo's and Mirai's don't.
        hwillis 5y ago
        High power batteries aren't like high power engines. They're built on the same production lines. High power engines prioritize power over cost; high power batteries just prioritize it over capacity. It's not challenging to make a cheap, small battery that can provide 200 kW. It just happens that it hasn't been prioritized. A provable example: 1,826 Sony VTC4 18650 cells will push 200 kW continuously. That's only 14 kWh of storage and weighs <100 kg. It's a 28.5"/72 cm square 3"/7.5 cm thick. I could personally build that battery for <10k USD. A full scale automaker should be able to do it for half that. That would almost triple (136 -> 336) the Mirai's power and put it (2050 kg @curb) in spitting distance of the 550i (390 kW, 2020 kg @curb). The BMW's MSRP starts 27k USD higher. Of course you would need to change the suspension and geometry completely, make the interior far nicer, and add even more power to be able to actually compete with the 550i, but the point stands. A small, powerful battery is cheap and easy to add to a FCV.
        bryanlarsen 5y ago
        If you are wiring all 1826 cells in parallel, that means you need 1826 battery controllers to achieve reasonable life and reliability. Plus the hassle and cost of using bus bars instead of wires. And it means that the battery module output is 3.6V at an insane amperage and needs a massive transformer for a reasonable voltage.
        hwillis 5y ago
        > If you are wiring all 1826 cells in parallel, that means you need 1826 battery controllers to achieve reasonable life and reliability. NB that I'm an electrical engineer and have built many batteries before, including from 18650s. First off, it is absolutely not necessary to have so many controllers; cell-level controllers are only used in the cheapest batteries. High-quality batteries will match cells individually and switch them in groups, which reduces the losses from running a bunch of parallel circuitry. This is not really different from simply using larger cells, as long as you can match them sufficiently well. Cell-level BMS is very cheap as a result, for example this single cell chip that costs 7 cents each: https://lcsc.com/product-detail/PMIC-Battery-Management_HY2213-BB3A_C113632.html https://lcsc.com/product-detail/PMIC-Battery-Management_HY22... > Plus the hassle and cost of using bus bars instead of wires. Only if you're using 18650s; if you are using prismatic cells you just solder or crimp the tabs to the HV supply. If you're using small-format cells, you would typically used stamped sheet current carriers rather than busbars. > And it means that the battery module output is 3.6V at an insane amperage and needs a massive transformer for a reasonable voltage. It certainly does not, because batteries are DC and you do not use transformers to convert their voltage. Transformers require you to convert to AC and back, but you can use an inductor ~100x smaller by using one of the many "boost" topologies. The basic idea is that you only need to convert to AC, and you don't need to rectify back to DC. You chop the high-current DC up very finely, then store 1-3 cycles in a very small inductor. If the inductor is sized just right, it will drain out current that is very close to DC. Naturally though you would really want to operate between the 245 volts of the Mirai's battery or the 650 volts of the Mirai's fuel stack. That would be something between a 68s27p pack and a 180s10p pack. That's far more efficient. You can still have cell-level BMS for every single cell- that IC I linked above is daisy-chainable, meaning it does not need a real 0v ground reference. It's perfectly happy working at whatever voltages on the two ends of the particular cell its connected to. In this case I'd opt for something closer to 68s- the more cells you have in series, the more susceptible your design is to degraded performance over time.
- hwillis 5y ago
  There is! Here's what it sounds like: https://www.youtube.com/watch?v=2dgzKW8EKMc https://www.youtube.com/watch?v=2dgzKW8EKMc Hydrogen is more energy-dense than gasoline, but it's much more of a pain in the ass. Gasoline is far denser than air but hydrogen is far less dense, so normal injection displaces a ton (30%) of oxygen from the cylinders. You need to use direct injection to get any kind of power out of hydrogen, and a very high-flow fuel pump. Combustion is also much hotter than normal, so you produce a ton of NOx compounds; that's why there's a huge catalytic converter on the back of the Toyota. Without the efficiency of a fuel cell there's quite a lot of loss of range. The potential for increased power+lower weight in high performance vehicles could do a lot to combat the halo effect of gasoline... or at least I hope so.
bkor 5y ago
> Hydrogen can be refilled quickly, in minutes Only if the gas station has enough hydrogen at the right pressure. After a few cars it'll need 45+min to build up pressure again. The gas stations are really expensive due to the problems, plus there are more restrictions on where they can be placed. Hydrogen for cars is great for companies such as Shell. For the foreseeable future they expect most of the Hydrogen to be created using non-green methods. Even if it's green, you'll need way more green energy (e.g. wind / solar). Way more profit to be had.
- jeffbee 5y ago
  What are the restrictions? There’s a hydrogen station in Berkeley in University Avenue across the street from a school and with houses on two sides.
  - ClumsyPilot 5y ago
    I think he meant fire safety of hydrogen requires more consideration than an electric charger.
    - bkor 5y ago
      In NL a hydrogen station needs to follow loads of safety requirements. So not just fire safety, safety in general. This was raised as an issue around hydrogen gas/fuel stations. Note that due to increase of EVs the safety requirements for garages have been increased (in NL). E.g. more monitoring is needed, automatic link to fire department, plus changes in construction requirements. Construction bit is due to an EV burning for longer. They basically demand thicker concrete walls and so on. This from memory and it's only what I've been reading (interested in safety; I don't work in construction).
Robotbeat 5y ago
Right. Similar to a liquid fueled car, but worse than an electric car in most circumstances. But the problem is there will never be an equivalent hydrogen network as there is gasoline network because hydrogen fueling stations are far more expensive to install and maintain. Either the station overhead ends up much higher than gasoline or hydrogen is used much more rarely. Electric car distance records as of 2018 are 1178km in a Model S and 1001km in a Model 3. https://www.teslarati.com/tesla-model-s-model-3-hypermile-world-records/amp/ https://www.teslarati.com/tesla-model-s-model-3-hypermile-wo... Model S Plaid+ next year is supposed to have ~50% greater range than the Model S used in that 2018 record. And has a nationwide charging network (and access to other EV charging networks, which themselves are becoming impressive... Lucid Air’s offering is also impressive). I just don’t see the attraction of hydrogen any more besides niche applications. The vehicles are much more expensive (Model 3 way cheaper than equivalent range Toyota Mirai), the charging is far less convenient and totally unavailable outside California, they’re slower, and the fuel is vastly more expensive, and they’re fundamentally less energy efficient. Heck, the Model 3 LR actually weighs less and has more range than the Toyota Mirai. Hydrogen cars are a bonfire of money. Conventional carmakers insistent on fast fueling capability ought to do plug-in hybrid. Even if you use synthesized fuel for the few trips that go beyond the electric range, the cost per mile (and cost per vehicle) would be way lower than hydrogen and you could use existing gas stations (although we’d need a lot fewer of them), and you still get the logistical benefit of home/work charging for commutes. You could switch everyone’s car for a plug in hybrid version today and they wouldn’t even know except it’d sound different. We could ban new vehicles without a plug and it wouldn’t ruin anyone’s corner case commute and a lot of people wouldn’t even realize it at first (just like many don’t realize they drive a mild hybrid). This is a far better argument than hydrogen cars’ “liquid fueling like experience! But only in a handful of stations in California at enormous expense...”
- nobleach 5y ago
  I think the two biggest sellers of Hydrogen electric over battery electric, are the fact that batteries have a useful life. That life degrades over time. Hydrogen doesn't have this characteristic. Secondly, cold weather doesn't affect Hydrogen electric vehicles the way that it does with battery electric. If one lives in a cold weather climate, owning a Tesla isn't as advantageous.

Cthulhu_ 5y ago

More like an electric car, if it's a hydrogen fuel cell car (I'm not sure if all hydrogen cars are that or if there's another variant that combusts the hydrogen)

jdblair 5y ago
Drives like an electric, refuels like a liquid fuel car (it uses a compressor, not electric charge).
- bryanlarsen 5y ago
  If by "electric" you mean "Prius", you're right. Tesla's and similar cars have great acceleration because they support massive currents at high voltages. They need this to support fast charging, the incremental cost of adding a high torque motor is small. Hydrogen cars have tiny batteries that don't need to support fast charging. Like a Prius.
  - hwillis 5y ago
    > Hydrogen cars have tiny batteries that don't need to support fast charging. Because that's what they think consumers want, not because of technological limitations. Size is not a requirement for high power batteries. The Porsche 918 has a 6.8 kWh battery that can do 210 kW. That's ~31 kW per kWh, compared to a top-end Model S at ~6 kW/kWh.
    - bryanlarsen 5y ago
      Yes, a $800K Hydrogen car would probably have a small but high power battery. But Nexo's and Mirai's don't.
      - hwillis 5y ago
        High power batteries aren't like high power engines. They're built on the same production lines. High power engines prioritize power over cost; high power batteries just prioritize it over capacity. It's not challenging to make a cheap, small battery that can provide 200 kW. It just happens that it hasn't been prioritized. A provable example: 1,826 Sony VTC4 18650 cells will push 200 kW continuously. That's only 14 kWh of storage and weighs <100 kg. It's a 28.5"/72 cm square 3"/7.5 cm thick. I could personally build that battery for <10k USD. A full scale automaker should be able to do it for half that. That would almost triple (136 -> 336) the Mirai's power and put it (2050 kg @curb) in spitting distance of the 550i (390 kW, 2020 kg @curb). The BMW's MSRP starts 27k USD higher. Of course you would need to change the suspension and geometry completely, make the interior far nicer, and add even more power to be able to actually compete with the 550i, but the point stands. A small, powerful battery is cheap and easy to add to a FCV.
        bryanlarsen 5y ago
        If you are wiring all 1826 cells in parallel, that means you need 1826 battery controllers to achieve reasonable life and reliability. Plus the hassle and cost of using bus bars instead of wires. And it means that the battery module output is 3.6V at an insane amperage and needs a massive transformer for a reasonable voltage.
        hwillis 5y ago
        > If you are wiring all 1826 cells in parallel, that means you need 1826 battery controllers to achieve reasonable life and reliability. NB that I'm an electrical engineer and have built many batteries before, including from 18650s. First off, it is absolutely not necessary to have so many controllers; cell-level controllers are only used in the cheapest batteries. High-quality batteries will match cells individually and switch them in groups, which reduces the losses from running a bunch of parallel circuitry. This is not really different from simply using larger cells, as long as you can match them sufficiently well. Cell-level BMS is very cheap as a result, for example this single cell chip that costs 7 cents each: https://lcsc.com/product-detail/PMIC-Battery-Management_HY2213-BB3A_C113632.html https://lcsc.com/product-detail/PMIC-Battery-Management_HY22... > Plus the hassle and cost of using bus bars instead of wires. Only if you're using 18650s; if you are using prismatic cells you just solder or crimp the tabs to the HV supply. If you're using small-format cells, you would typically used stamped sheet current carriers rather than busbars. > And it means that the battery module output is 3.6V at an insane amperage and needs a massive transformer for a reasonable voltage. It certainly does not, because batteries are DC and you do not use transformers to convert their voltage. Transformers require you to convert to AC and back, but you can use an inductor ~100x smaller by using one of the many "boost" topologies. The basic idea is that you only need to convert to AC, and you don't need to rectify back to DC. You chop the high-current DC up very finely, then store 1-3 cycles in a very small inductor. If the inductor is sized just right, it will drain out current that is very close to DC. Naturally though you would really want to operate between the 245 volts of the Mirai's battery or the 650 volts of the Mirai's fuel stack. That would be something between a 68s27p pack and a 180s10p pack. That's far more efficient. You can still have cell-level BMS for every single cell- that IC I linked above is daisy-chainable, meaning it does not need a real 0v ground reference. It's perfectly happy working at whatever voltages on the two ends of the particular cell its connected to. In this case I'd opt for something closer to 68s- the more cells you have in series, the more susceptible your design is to degraded performance over time.
hwillis 5y ago
There is! Here's what it sounds like: https://www.youtube.com/watch?v=2dgzKW8EKMc https://www.youtube.com/watch?v=2dgzKW8EKMc Hydrogen is more energy-dense than gasoline, but it's much more of a pain in the ass. Gasoline is far denser than air but hydrogen is far less dense, so normal injection displaces a ton (30%) of oxygen from the cylinders. You need to use direct injection to get any kind of power out of hydrogen, and a very high-flow fuel pump. Combustion is also much hotter than normal, so you produce a ton of NOx compounds; that's why there's a huge catalytic converter on the back of the Toyota. Without the efficiency of a fuel cell there's quite a lot of loss of range. The potential for increased power+lower weight in high performance vehicles could do a lot to combat the halo effect of gasoline... or at least I hope so.

bkor 5y ago

> Hydrogen can be refilled quickly, in minutes Only if the gas station has enough hydrogen at the right pressure. After a few cars it'll need 45+min to build up pressure again. The gas stations are really expensive due to the problems, plus there are more restrictions on where they can be placed. Hydrogen for cars is great for companies such as Shell. For the foreseeable future they expect most of the Hydrogen to be created using non-green methods. Even if it's green, you'll need way more green energy (e.g. wind / solar). Way more profit to be had.

jeffbee 5y ago
What are the restrictions? There’s a hydrogen station in Berkeley in University Avenue across the street from a school and with houses on two sides.
- ClumsyPilot 5y ago
  I think he meant fire safety of hydrogen requires more consideration than an electric charger.
  - bkor 5y ago
    In NL a hydrogen station needs to follow loads of safety requirements. So not just fire safety, safety in general. This was raised as an issue around hydrogen gas/fuel stations. Note that due to increase of EVs the safety requirements for garages have been increased (in NL). E.g. more monitoring is needed, automatic link to fire department, plus changes in construction requirements. Construction bit is due to an EV burning for longer. They basically demand thicker concrete walls and so on. This from memory and it's only what I've been reading (interested in safety; I don't work in construction).

Robotbeat 5y ago

Right. Similar to a liquid fueled car, but worse than an electric car in most circumstances. But the problem is there will never be an equivalent hydrogen network as there is gasoline network because hydrogen fueling stations are far more expensive to install and maintain. Either the station overhead ends up much higher than gasoline or hydrogen is used much more rarely. Electric car distance records as of 2018 are 1178km in a Model S and 1001km in a Model 3. https://www.teslarati.com/tesla-model-s-model-3-hypermile-world-records/amp/ https://www.teslarati.com/tesla-model-s-model-3-hypermile-wo... Model S Plaid+ next year is supposed to have ~50% greater range than the Model S used in that 2018 record. And has a nationwide charging network (and access to other EV charging networks, which themselves are becoming impressive... Lucid Air’s offering is also impressive). I just don’t see the attraction of hydrogen any more besides niche applications. The vehicles are much more expensive (Model 3 way cheaper than equivalent range Toyota Mirai), the charging is far less convenient and totally unavailable outside California, they’re slower, and the fuel is vastly more expensive, and they’re fundamentally less energy efficient. Heck, the Model 3 LR actually weighs less and has more range than the Toyota Mirai. Hydrogen cars are a bonfire of money. Conventional carmakers insistent on fast fueling capability ought to do plug-in hybrid. Even if you use synthesized fuel for the few trips that go beyond the electric range, the cost per mile (and cost per vehicle) would be way lower than hydrogen and you could use existing gas stations (although we’d need a lot fewer of them), and you still get the logistical benefit of home/work charging for commutes. You could switch everyone’s car for a plug in hybrid version today and they wouldn’t even know except it’d sound different. We could ban new vehicles without a plug and it wouldn’t ruin anyone’s corner case commute and a lot of people wouldn’t even realize it at first (just like many don’t realize they drive a mild hybrid). This is a far better argument than hydrogen cars’ “liquid fueling like experience! But only in a handful of stations in California at enormous expense...”

nobleach 5y ago
I think the two biggest sellers of Hydrogen electric over battery electric, are the fact that batteries have a useful life. That life degrades over time. Hydrogen doesn't have this characteristic. Secondly, cold weather doesn't affect Hydrogen electric vehicles the way that it does with battery electric. If one lives in a cold weather climate, owning a Tesla isn't as advantageous.