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Has anyone tried to calculate roughly how cheap and energy dense batteries have to get before hydrogen fuel cells become uncompetetive for small/medium vehicles

by audunw 10y ago

Has anyone tried to calculate roughly how cheap and energy dense batteries have to get before hydrogen fuel cells become uncompetetive for small/medium vehicles? I figure, hydrogen's technological downside is a fuel that's hard to store and handle (can't fill a portable tank and carry around like with gasoline, can't fill at home like with batteries). Pure battery's downside is shorter range and longer time to "fill". Hydrogen's economical downside is a more complex system with more parts to assemble. Battery's downside is the cost of large amounts of batteries. In both cases it seems that hydrogen has the upper hand in the short term, if they solve the cost of the fuel cell itself. But in both cases it seems to me like pure batteries have downsides that are likely to improve over time. It would be interesting to know where the break-even point is, given we have a cheap fuel cell. I'm worried that the hydrogen fuel cells are a bit of a blind alley for cars. Heavy trucks and cargo ships is another matter though. But then maybe biofuels aren't so bad if we can just combust them cleanly enough.

pjc50 10y ago
Surely this is the other way round: plug-in electric vehicles are starting to take off on batteries, having the upper hand in the short term. While hydrogen hasn't quite taken off because of the handling difficulties. I think it's more likely we'll see a renewables-to-methanol/ethanol solution than a hydrogen economy. There are various proposed processes for this, including the USAF's nuclear-to-jetfuel one which claims $6/USgal amortised cost.
- maxerickson 10y ago
  Butanol! It has better energy density than ethanol and absorbs less water than ethanol and is not as good a solvent as ethanol (so engine parts last longer).
- ryao 10y ago
  Renewables to methane probably makes more sense. Methane is cheap and easy to produce. Using it skips the additional step of methane to methanol conversion. There are already plenty of methane powered cars on the road in Europe and a few on the road in the US. Renewable production of methane is already being done at scale by BioSNG in Sweden. This claims that it is not yet competitive with untaxed natural gas from fossil fuels though: http://www.biosng.com/fileadmin/biosng/user/documents/reports/The_Economy_of_Large_Scale_Biomass_to_Bio-Methane.pdf http://www.biosng.com/fileadmin/biosng/user/documents/report... Presumably, the taxes in Sweden are sufficient to make it feasible.
  - hx87 10y ago
    Methane still forces you to run on the Otto cycle or a variant thereof, not the more efficient Diesel cycle, so unless engine makers get HCCI right, renewables-to-diesel would still be a better choice.
    - ryao 10y ago
      The only thing that matters for adoption of renewables in transportation is $/mile. The efficiency of the heat engines is irrelevant. Natural gas is cheaper to make in a renewable manner than diesel (Europe is already mass producing natural gas from biomass) and has higher energy densities in J/g, which makes it suitable for transportation. The lower combustion temperatures do lower efficiency, but they also lower NOx emissions, which are a difficult problem for diesel. As far as aviation is concerned, natural gas could be more efficient not only due to the lower weight, but also due to the fuel being "precooled" in its liquid state: https://en.m.wikipedia.org/wiki/Precooled_jet_engine https://en.m.wikipedia.org/wiki/Precooled_jet_engine
ZeroGravitas 10y ago
The consensus seems to be that hydrogen fuel cells have never been competitive for cars, so any future reduction in battery costs and building out of charging infrastructure is only going to make that worse. So it's interesting that you think they have a short term advantage. There's also plug-in hybrid cars which would fill the gaps that pure EV don't yet cover better than fuel cells, by allowing short commutes or restricted city centres to be pure electric with no emisions, while still allowing for quick refuels on longer journies and defeating range anxiety.
- audunw 10y ago
  > So it's interesting that you think they have a short term advantage. I think you missed this part ", if they solve the cost of the fuel cell itself. " Until they solve the high cost of the fuel cell, no, they don't have an advantage at all. But I feel like it's reasonable to assume that it can be solved. That is, I want to give hydrogen the benefit of doubt, but even then I see issues.
  - m_mueller 10y ago
    AFAIK even if the fuel cell was free it would still not be competitive. The reason being that you need 2-3x more electrical energy to get the same kinetiv energy if you store it in hydrogen rather than lithium based batteries. There goes the entire price advantage you have over gasoline cars - in order to get the mass market it needs to be cheaper both upfront and to run it, which only batteries can achieve, safe some revolutionary new way to convert electricity to hydrogen. There could be niche usecases though, such as long range trucks or buses - if energy density is more important than fuel cost.
- Pigo 10y ago
  I would love to get some kind of hybrid vehicle. But I really want to talk to someone who has had one for a period of time, in the real world, before I commit to it. I have no clue what maintenance is like, or more importantly costs. Can you replace components, or do you have to buy entire assemblies when something breaks?
Shivetya 10y ago
The two issues I see with pure battery solutions are weight and recharge time. As density increases we can solve the weight issue which is a serious negative currently but the issue with more density/etc is that charging systems may evolve beyond the point of being installed anywhere but dedicated facilitates. Has anyone calculated the maximum in KW/H or such that a normal house hold could sustain from standard street connections?
- audunw 10y ago
  > Has anyone calculated the maximum in KW/H or such that a normal house hold could sustain from standard street connections? I don't feel like this is very relevant. The number of people who can't charge their daily need within 8 hours on a 10kW connection is on the order of one in every 10'000, if not less. Or maybe you assume people charges at home in the same pattern as how they fill gasoline? I.e., they only charge when the battery is down to like 30%? That's probably not gonna be the case. If you have the option to charge at home, there's no reason not to plug it in every night. A significant number of people will need to drive long distance 2 or more days in a row, every once in a while, so that has to be solved by rapid charging stations. We will end up with ~350kW rapid chargers (the rough physical limit with water cooled cables), which is almost fast enough that it'd feel like filling gasoline does. But yeah, that will be dedicated facilities with grid storage scale batteries to smooth power consumption.
  - vvanders 10y ago
    Yup in ~2 years of EV ownership only time I've every wanted faster charging at home(~15kW) was once after ~7 hours of driving with 5% left when I finally got home. Just ended up taking the other car we had, if I needed to I could have just hung out at the supercharger for another 15 minutes.
  - pbhjpbhj 10y ago
    What's the charging limit on the car end of the cables limit it to 350kW. If it's a purpose built charge-station then why not superconducting cabling, or pumped liquid nitrogen, or ... that would push to the limit of the car/battery.
maxerickson 10y ago
There's toy investment in hydrogen and quite a lot of vehicles on the road using LNG. I don't think it is really a blind alley, it's just that fuel cells exist so they get talked about.

by audunw 10y ago

pjc50 10y ago

Surely this is the other way round: plug-in electric vehicles are starting to take off on batteries, having the upper hand in the short term. While hydrogen hasn't quite taken off because of the handling difficulties. I think it's more likely we'll see a renewables-to-methanol/ethanol solution than a hydrogen economy. There are various proposed processes for this, including the USAF's nuclear-to-jetfuel one which claims $6/USgal amortised cost.

maxerickson 10y ago
Butanol! It has better energy density than ethanol and absorbs less water than ethanol and is not as good a solvent as ethanol (so engine parts last longer).
ryao 10y ago
Renewables to methane probably makes more sense. Methane is cheap and easy to produce. Using it skips the additional step of methane to methanol conversion. There are already plenty of methane powered cars on the road in Europe and a few on the road in the US. Renewable production of methane is already being done at scale by BioSNG in Sweden. This claims that it is not yet competitive with untaxed natural gas from fossil fuels though: http://www.biosng.com/fileadmin/biosng/user/documents/reports/The_Economy_of_Large_Scale_Biomass_to_Bio-Methane.pdf http://www.biosng.com/fileadmin/biosng/user/documents/report... Presumably, the taxes in Sweden are sufficient to make it feasible.
- hx87 10y ago
  Methane still forces you to run on the Otto cycle or a variant thereof, not the more efficient Diesel cycle, so unless engine makers get HCCI right, renewables-to-diesel would still be a better choice.
  - ryao 10y ago
    The only thing that matters for adoption of renewables in transportation is $/mile. The efficiency of the heat engines is irrelevant. Natural gas is cheaper to make in a renewable manner than diesel (Europe is already mass producing natural gas from biomass) and has higher energy densities in J/g, which makes it suitable for transportation. The lower combustion temperatures do lower efficiency, but they also lower NOx emissions, which are a difficult problem for diesel. As far as aviation is concerned, natural gas could be more efficient not only due to the lower weight, but also due to the fuel being "precooled" in its liquid state: https://en.m.wikipedia.org/wiki/Precooled_jet_engine https://en.m.wikipedia.org/wiki/Precooled_jet_engine

ZeroGravitas 10y ago

The consensus seems to be that hydrogen fuel cells have never been competitive for cars, so any future reduction in battery costs and building out of charging infrastructure is only going to make that worse. So it's interesting that you think they have a short term advantage. There's also plug-in hybrid cars which would fill the gaps that pure EV don't yet cover better than fuel cells, by allowing short commutes or restricted city centres to be pure electric with no emisions, while still allowing for quick refuels on longer journies and defeating range anxiety.

audunw 10y ago
> So it's interesting that you think they have a short term advantage. I think you missed this part ", if they solve the cost of the fuel cell itself. " Until they solve the high cost of the fuel cell, no, they don't have an advantage at all. But I feel like it's reasonable to assume that it can be solved. That is, I want to give hydrogen the benefit of doubt, but even then I see issues.
- m_mueller 10y ago
  AFAIK even if the fuel cell was free it would still not be competitive. The reason being that you need 2-3x more electrical energy to get the same kinetiv energy if you store it in hydrogen rather than lithium based batteries. There goes the entire price advantage you have over gasoline cars - in order to get the mass market it needs to be cheaper both upfront and to run it, which only batteries can achieve, safe some revolutionary new way to convert electricity to hydrogen. There could be niche usecases though, such as long range trucks or buses - if energy density is more important than fuel cost.
Pigo 10y ago
I would love to get some kind of hybrid vehicle. But I really want to talk to someone who has had one for a period of time, in the real world, before I commit to it. I have no clue what maintenance is like, or more importantly costs. Can you replace components, or do you have to buy entire assemblies when something breaks?

Shivetya 10y ago

The two issues I see with pure battery solutions are weight and recharge time. As density increases we can solve the weight issue which is a serious negative currently but the issue with more density/etc is that charging systems may evolve beyond the point of being installed anywhere but dedicated facilitates. Has anyone calculated the maximum in KW/H or such that a normal house hold could sustain from standard street connections?

audunw 10y ago
> Has anyone calculated the maximum in KW/H or such that a normal house hold could sustain from standard street connections? I don't feel like this is very relevant. The number of people who can't charge their daily need within 8 hours on a 10kW connection is on the order of one in every 10'000, if not less. Or maybe you assume people charges at home in the same pattern as how they fill gasoline? I.e., they only charge when the battery is down to like 30%? That's probably not gonna be the case. If you have the option to charge at home, there's no reason not to plug it in every night. A significant number of people will need to drive long distance 2 or more days in a row, every once in a while, so that has to be solved by rapid charging stations. We will end up with ~350kW rapid chargers (the rough physical limit with water cooled cables), which is almost fast enough that it'd feel like filling gasoline does. But yeah, that will be dedicated facilities with grid storage scale batteries to smooth power consumption.
- vvanders 10y ago
  Yup in ~2 years of EV ownership only time I've every wanted faster charging at home(~15kW) was once after ~7 hours of driving with 5% left when I finally got home. Just ended up taking the other car we had, if I needed to I could have just hung out at the supercharger for another 15 minutes.
- pbhjpbhj 10y ago
  What's the charging limit on the car end of the cables limit it to 350kW. If it's a purpose built charge-station then why not superconducting cabling, or pumped liquid nitrogen, or ... that would push to the limit of the car/battery.

maxerickson 10y ago

There's toy investment in hydrogen and quite a lot of vehicles on the road using LNG. I don't think it is really a blind alley, it's just that fuel cells exist so they get talked about.