Fuel cells

[mike killay]

First Hydrogen Bike - YouTube
No mention of how much a cylinder of Hydrogen would cost.

 

[neptune]

This is very interesting. However, in its current form, it is not world changing . I would guess that the hydrogen cylinder itself is quite heavy. Its performance does not exceed the very best current ebikes by any great margin. Its real advantage is its rapid recharging ability. This however does not manifest itself unless the infrastructure exists to support it. You would need to be able to buy hydrogen at your local petrol station, or Asda. I suspect that the thing that will kill it will be initial cost and recharge costs.

 

[mike killay]

What they also do not tell us is what if the electric motor was replaced by a small ICE engine. How would that perform on hydrogen.

 

[neptune]

I think I read somewhere that the efficiency of a fuel cell can be double that of an IC engine.

 

[flecc]

It's not the first one by far, Aprilia produced a very practical hydrogen powered prototype e-bike a whole decade ago!

Also several years ago one continental enthusiast produced a hydrogen powered fuel cell recumbent trike with a 1000 lbs pressure tank which had an over 50 mile range. He demonstrated it at a number of venues and shows.

I think I read somewhere that the efficiency of a fuel cell can be double that of an IC engine.

Two very different things, one is a "fuel" supply source like a battery, the other a fuel user, so the efficiency of them cannot be compared in any realistic way.
.

 

[neptune]

@flecc. IMO the only meaningful way to compare the efficiency would be to do a mileage range test with the setup as described, and then, leaving the same size hydrogen cylinder in place, replace the fuel cell and electric motor with a small IC engine, and repeat the range test.

 

[flecc]

Not what was said though, the comparison of fuel cell efficiency with an ic engine was what I answered.

In that comparison, the fuel to mechanical output cycle was incomplete for the hydrogen, but complete for an ic engine. Add the efficiency loss of the electric motor to the former and that would change the comparative efficiency.

 

[neptune]

@flecc. Yes I understand what you are getting at. But if we assume an average efficiency for the electric motor and controller of say 80% , I believe that your cylinder of hydrogen would take you quite a bit further than if you burned it in an IC engine. What do you think?

 

[flecc]

@flecc. Yes I understand what you are getting at. But if we assume an average efficiency for the electric motor and controller of say 80% , I believe that your cylinder of hydrogen would take you quite a bit further than if you burned it in an IC engine. What do you think?

I don't know to be honest, though hydrogen using fuel cells can be very efficient. If an ic engine was specifically designed for hydrogen use, it might substantially change the position though. Given the true gas nature and volatility of hydrogen as opposed to atomised petrol, I think an optimised piston engine design would have over-square bore/stroke ratio and be very much higher revving with low torque but high power.

Of course if the whole chain is taken for comparison, production of the fuel through to mechanical output, the hydrogen versus petrol/diesel position could shift quite a lot.

Technical problems continue to impede fuel cell introduction though, their life in mobile applications is very poor at present and replacement cost too high. London trialled three single deck buses and has ordered eight more after a successful trial, but at a million pounds each, success is a qualified term since that million pounds for one buys three diesel double deckers! Given the high capital cost and cost of short fuel cell life, the whole fleet of hydrogen buses would at least quadruple fares.

 

[neptune]

@flecc. You raise some interesting points.Yes, you would probably gain efficiency with a high revving oversquare hydrogen engine. However the downside would be the necessity for a multistage reduction gear train, so there would be some losses there. The emissions would be as clean as the fuel cell, but it would of course be noisier. It would probably be much cheaper . I think that fuel cells need a lot more Rand D before they become commonplace. Regarding the busses, what is the odd million pounds if you are spending other peoples money?

 

[flecc]

Regarding the busses, what is the odd million pounds if you are spending other peoples money?

True, until it has to be recovered from fares, which is what will have to happen if they buy too many of them. At present the cost of eleven is hidden in a fleet of 6800 buses and the fares from around half of the six million passenger trips every day (the young to 16/18 and the elderly travel free in London).