29 ms·

Peugeot Bets on a Different Kind of Hybrid Car

35 points by vdondeti 14y ago

stcredzero 14y ago
Isn't compressed air somewhat like capacitors? So-so energy density, but great power density? It's supposed to be great for a burst of speed, but not for lots of range.
- mistercow 14y ago
  Perhaps, but my understanding is that gas engines are really very efficient at keeping you at speed; it's accelerating from a stop where you use a lot of fuel. So a burst of power with little range can win out if it adds a lot less mass to the car than the battery and electric motor in an electric hybrid.
  - ams6110 14y ago
    Yep, it's a completely mechanical way to recover the energy expended in braking and apply it to getting the vehicle rolling again. In this way the gasoline engine is mainly used to maintain speed and climb hills. Other experimental vehicles have used flywheels to capture braking energy, but the advantage of compressed gas is that it can store the energy indefinitely (assuming no leaks). Sounds like it could be more efficient and reliable than the electrochemical process that electric hybrids use, with less weight and environmental concerns related to battery manufacture and disposal.
    - pkulak 14y ago
      Well, there's always a risk when you're storing energy. In this case it would be explosion. Could be a very small risk, though.
      - pilap82 14y ago
        I had the same "concern" but they say: The energy stored in the nitrogen tank is small — equivalent to only about five teaspoons, or a couple dozen cubic centimeters, of gasoline So I guess that the explosion of a tank full of "about five teaspoon" should not wreak too much damage :)
        DeepDuh 14y ago
        What I gather from the article it's not the stored energy that's of some concern, but the 250 bar nominal pressure in the tanks - a rupture might lead to metal splinters flying around. However, they claim that the car's underfloor is enough shielding. I'd say let some independent safety tests figure that one out. So far I think this is a very promising concept - I was always weary about electrical hybrids because of the use of rare earth metals and the environmental impact in some regions because of that. Putting some nitrogen tanks and mechanical/electronic bits in a car to achieve the same effect for city driving seems like a big winner - mass produced I'd think you could make those cars only minimally more expensive than normal gas powered ones. Electrical Hybrid car prices, meanwhile, don't seem to scale down much.
        gus_massa 14y ago
        Here in Argentina ~1/5 of the cars use compressed natural gas (mostly methane) tanks at 200 bars, because it is cheaper than gasoline. I don't remember any horror story of a crash, and these cars are generally considered almost as safe as the usual cars. The main drawback is that the tank is very big and uses half of the back trunks. More information: http://en.wikipedia.org/wiki/Compressed_natural_gas http://en.wikipedia.org/wiki/Compressed_natural_gas
        StavrosK 14y ago
        We do the same in Greece, the tank is 50-60 liters (not sure if that volume is when the gas is at STP or compressed), though, and takes around the room of the spare. That's also where they put it.
        mistercow 14y ago
- pkulak 14y ago
  There could be huge gains if it really can store all the breaking energy and subsequently release all of it quickly (even with what must be pretty large losses in a system like this). On my Prius anything more than light breaking engages the disc brakes and the electric motor is not able to accelerate the car at all.
rikacomet 14y ago
Oh gosh, I don't want to complain, but I reported this about 1 month ago, and it didn't even get 1 point. It seems different timezones, have different taste :P hehe
- lnanek2 14y ago
  Also strongly depends on what else is going on when it is posted. Only time I can recall being on the front page for long was when a hurricane had tons of people out of power and not posting. :)
  - rikacomet 14y ago
    haha yeah, people can be odd sometimes. I just had a -4 on a post saying that a particular thread (is so good) that it should go front page on HN, apparently it did, but oh the irony.
- gus_massa 14y ago
  I saw you submission last month. The problem is that it looked like direct copy of an AFP new that looked like a direct copy of a press release of Peugeot, so it was difficult to know how interesting the new method was and how much was only hype. The NYT has a little more credibility and the article seams to be written more independently, but until there are some more real use case reports with the new cars it's still difficult to separate the reality from the hype.
  - rikacomet 14y ago
    Yeah, I see what you mean. I will remember that in future. Cheers, and thanks for reply.

35 points by vdondeti 14y ago

Isn't compressed air somewhat like capacitors? So-so energy density, but great power density? It's supposed to be great for a burst of speed, but not for lots of range.

mistercow 14y ago
Perhaps, but my understanding is that gas engines are really very efficient at keeping you at speed; it's accelerating from a stop where you use a lot of fuel. So a burst of power with little range can win out if it adds a lot less mass to the car than the battery and electric motor in an electric hybrid.
- ams6110 14y ago
  Yep, it's a completely mechanical way to recover the energy expended in braking and apply it to getting the vehicle rolling again. In this way the gasoline engine is mainly used to maintain speed and climb hills. Other experimental vehicles have used flywheels to capture braking energy, but the advantage of compressed gas is that it can store the energy indefinitely (assuming no leaks). Sounds like it could be more efficient and reliable than the electrochemical process that electric hybrids use, with less weight and environmental concerns related to battery manufacture and disposal.
  - pkulak 14y ago
    Well, there's always a risk when you're storing energy. In this case it would be explosion. Could be a very small risk, though.
    - pilap82 14y ago
      I had the same "concern" but they say: The energy stored in the nitrogen tank is small — equivalent to only about five teaspoons, or a couple dozen cubic centimeters, of gasoline So I guess that the explosion of a tank full of "about five teaspoon" should not wreak too much damage :)
      - DeepDuh 14y ago
        What I gather from the article it's not the stored energy that's of some concern, but the 250 bar nominal pressure in the tanks - a rupture might lead to metal splinters flying around. However, they claim that the car's underfloor is enough shielding. I'd say let some independent safety tests figure that one out. So far I think this is a very promising concept - I was always weary about electrical hybrids because of the use of rare earth metals and the environmental impact in some regions because of that. Putting some nitrogen tanks and mechanical/electronic bits in a car to achieve the same effect for city driving seems like a big winner - mass produced I'd think you could make those cars only minimally more expensive than normal gas powered ones. Electrical Hybrid car prices, meanwhile, don't seem to scale down much.
        gus_massa 14y ago
        Here in Argentina ~1/5 of the cars use compressed natural gas (mostly methane) tanks at 200 bars, because it is cheaper than gasoline. I don't remember any horror story of a crash, and these cars are generally considered almost as safe as the usual cars. The main drawback is that the tank is very big and uses half of the back trunks. More information: http://en.wikipedia.org/wiki/Compressed_natural_gas http://en.wikipedia.org/wiki/Compressed_natural_gas
        StavrosK 14y ago
        We do the same in Greece, the tank is 50-60 liters (not sure if that volume is when the gas is at STP or compressed), though, and takes around the room of the spare. That's also where they put it.
      - mistercow 14y ago
pkulak 14y ago
There could be huge gains if it really can store all the breaking energy and subsequently release all of it quickly (even with what must be pretty large losses in a system like this). On my Prius anything more than light breaking engages the disc brakes and the electric motor is not able to accelerate the car at all.

rikacomet 14y ago

Oh gosh, I don't want to complain, but I reported this about 1 month ago, and it didn't even get 1 point. It seems different timezones, have different taste :P hehe

lnanek2 14y ago
Also strongly depends on what else is going on when it is posted. Only time I can recall being on the front page for long was when a hurricane had tons of people out of power and not posting. :)
- rikacomet 14y ago
  haha yeah, people can be odd sometimes. I just had a -4 on a post saying that a particular thread (is so good) that it should go front page on HN, apparently it did, but oh the irony.
gus_massa 14y ago
I saw you submission last month. The problem is that it looked like direct copy of an AFP new that looked like a direct copy of a press release of Peugeot, so it was difficult to know how interesting the new method was and how much was only hype. The NYT has a little more credibility and the article seams to be written more independently, but until there are some more real use case reports with the new cars it's still difficult to separate the reality from the hype.
- rikacomet 14y ago
  Yeah, I see what you mean. I will remember that in future. Cheers, and thanks for reply.