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Print 44 comment(s) - last by ghost49x.. on Mar 27 at 9:48 PM

No fuel cell vehicles from VW on the horizon

Source: Auto News





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RE: The solution is on youtube
By ppardee on 3/22/2013 2:39:26 PM , Rating: 3
The problem is that making hydrogen from water, then burning the hydrogen is a negative energy equation. You will always use more energy creating the hydrogen than you get from burning it. Hydrogen isn't a fuel, it's an energy storage medium at best.

If it's just an energy storage medium, wouldn't it be better to use a battery that doesn't explode when you look at it sideways?


RE: The solution is on youtube
By Visual on 3/25/2013 5:11:09 AM , Rating: 2
Dude, every closed process is a "negative energy equation". That is not an issue.

Also the actual efficiency of the process is as bad as you make it sound.
Average fuel cells are 40-60% efficient, and electrolysis efficiency can vary from 50% to up to 95%. Combined gives a worst case of 20%, which might sound terrible but is in fact comparable with ICE efficiency. And it is also obvious that above 50% efficiency is possible with the right electrolysers today. That is worse than the 90% figure possible with batteries, but not by too much, and especially not when looking at batteries in realistic situations instead of theoretical max, taking into account self-discharge, temperature effects, limited capacity and recharge time.

And there is still room for future improvement in fuel cells efficiency, with the theoretical maximum given as 83% without heat recapture. Also systems with heat recapture, even though not usable in something like a car currently, already can boost fuel cells to 80-90% efficiency. In the future maybe we can adapt them for cars as well.


RE: The solution is on youtube
By Visual on 3/25/2013 5:13:42 AM , Rating: 2
"is as bad as you make it sound"... yeah... obviously that is exactly what I meant to say... not.
My point got defeated by Dailytech's lack of edit button.


RE: The solution is on youtube
By zephyrprime on 3/25/2013 12:00:35 PM , Rating: 2
The problem with this analysis is that it doesn't take into the fact that gasoline engines effectively get free energy from free oxygen in the atmosphere. Of course, the energy in the oxygen comes from somewhere (plants) but we don't care about that because the cost is free for humans. With electrolysis, even with 95% efficient electrolysis, a lot more than 5% of energy is wasted producing oxygen which can be gotten for free in the atmosphere.


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