Hydrogen Fuel Cells

[pepdavies]

Just wondering if anyone else has experience of these? I just bought a 2.0 Coupe with one fitted and I'm getting over 40 mpg without much effort. It seems really cool, it splits distilled water and pumps the hydrogen into the airbox. It cost the previous owner almost as much as I paid for his car lol

[KozmoNaut]

It's bullshit.

The "fuel cell" works by splitting water into oxygen and hydrogen. Due to entropy, you can never reclaim all the energy it takes to do this. It's a net loss, in other words. Never mind the additional cost of topping up with distilled water.

Anyone telling you anything else may as well be selling you the Eiffel tower.

[pepdavies]

I understand your point about entropy but they claim you get more energy out of the petrol that would have been wasted. All i know is I am am getting better fuel economy than i expected. I wouldn't have paid for the install but I'm definitely leaving it connected.

[KozmoNaut]

Think about it. If there really are gains to be had from adding a water-cracking and hydrogen system to an engine, why doesn't every manufacturer use them? As far as I know, not a single vehicle has been delivered with such a system installed from the factory.

http://www.autoblog.com/2008/08/04/why- ... r-mileage/
http://www.autoblog.com/2008/08/12/hho- ... ails-in-t/
http://www.popularmechanics.com/cars/a3983/4310717/

To date, there has not been a single verified result of such a system having any positive effect on power or fuel mileage on any sort of vehicle, petrol or diesel. In other words, it is a complete waste of money, and your car would get the exact same fuel economy (or better!) without the system.

[gumby6371]

I'm also dubious but haven't looked into it.
Is the 40MPG calculated by the car or good old pen and paper?
I'd do a brim to brim test and also work out actual total costs per mile compared to just petrol.

In many cases the economy figure you see on the screen is a 'best guess' made by the ECU, my Megane tells me 51MPG pootling around town but actual is around 49.5. Needless to say I'm absolutely gutted at such poor figures

[pepdavies]

The mpg figure comes from the car, I'll try to do the sums myself. I suppose I can compare it to standard by disconnecting the power wire, will be interesting to compare.

[steve_earwig]

I thought hydrogen fuel cells were a way of storing/generating power on, erm, space ships

Can you disconnect the fuel pump and just run it on hydrogen?

[pepdavies]

I don't see how it would work on just hydrogen. Probably needs a specialised engine like in the BMWs. All new to me though!

[KozmoNaut]

It's not really a fuel cell, which generates electricity by oxidizing hydrogen.

The device in pepdavies' car uses electricity to split water into hydrogen and oxygen, which is then presumably fed into the intake at some point, and combusted alongside the petrol+air mixture in the engine. The proponents claim that this increases the power and efficiency, since you're basically adding more fuel and oxygen.

Common sense tells us that the electricity to split the water comes from the alternator, which is driven by the engine. This increases the load on the engine, causing any supposed gains to be nullified, at best. In reality, there is always some energy lost in such a process, so the end result is a net loss of efficiency.