No Fuel like an old fuel

[neptune]

For more years than I care to remember, we have been told that cars of the future will run on hydrogen. The main advantage of hydrogen as a fuel is that the main constituent of the exhaust gas is water vapour. One problem is that special alloys may have to be used in the engine, as hydrogen combustion can cause steel to go brittle. There is however a main disadvantage that is seldom discussed . Think of a fuel tanker delivering fuel to your local garage. A large articulated fuel lorry with 6 axles has a maximum permitted gross weight of 44 tonnes. So with a payload around 30 tonnes it will carry enough petrol or diesel to refuel about 350 cars.Now think of a hydrogen tanker. Hydrogen has to be compressed to a very high pressure to make its transport worthwhile. This would need a tank with walls of three inch thick steel. This would refuel less than 20 cars. So the transport could cost more than the fuel.

The other problem is that, in a sense, hydrogen is not a source of energy, it is an energy carrier. Hydrogen is made by the electrolysis of water. Using conventional electrolysis , you need to put in more energy, as electricity, than you gain from burning the hydrogen. That is fine if you have a source of free electricity, but such sources have yet to be available. There have been many claims of super efficient methods of electrolysis, but none have made it to the market place.

Another way to transport hydrogen gas, is in the form of metal hydrides, where the hydrogen is chemically combined with other elements. This would be far too expensive on any sort of large scale . I did read recently where a manufacturer of ebikes [Pedalgo?] was planning to market an ebike with a fuel cell as a range extender. I think the idea was to charge a battery at about 2 amps as you rode the bike, giving a claimed range of about 80 miles. The fuel, a metal hydride, was carried in an exchangeable cartridge. If it comes to market, the fuel cell on its own is likely to cost around 2 thousand pounds, and so is unlikely to be a world changer. You could by one hell of a battery for that money.

So I do not see hydrogen powered bikes any time soon.

 

[flecc]

There has been an Aprilia hydrogen fuel cell powered e-bike a few years ago, and one German enthusiast built a realistic hydrogen fuel cell recumbent trike with a range of 56 miles from it's 1000 lbs pressure cylinder. It was demonstrated at a number of locations.

As you say though, production of the hydrogen is a big problem which only nuclear can deal with realistically, either with electrolysis or more efficiently by direct production. The latter was coincidentally achieved by two of the reactors at Fukushima after the tsunami destroyed their cooling supply, though in that case the hydrogen was the vehicle that carried out the caesium 137 and iodine 131 to pollute the area.

Of course in normal production the hydrogen wouldn't be contaminated and would be captured direct from the reactor. One day, but not just yet while oil is still relatively easy to get and use.

 

[neptune]

@Flecc. It is interesting that fuel cell powered bikes have been ridden, in a limited way . There is still the problem of transporting hydrogen. You, like me, are old enough to remember that when nuclear energy was first proposed, it was going to provide electricity that would be so cheap that it would not be worth metering .Sadly, this proved not to be the case. Another possibility would be to generate hydrogen at the local garage, or even at home, using off peak electricity. In a way, a hydrogen car is just an electric car with a novel type of battery. Sooner or later, [I would hope sooner] nukes as we know them will be history. Not a good technology to base our future on, as our grandchildren will have enough to do to clear up the mess we have made already.I know that is a matter of opinion , but that is mine.

 

[flecc]

I think you probably know mine is the opposite view, most of the so-called mess being useful fuel for future use, it's usage doing much of the clearing. Many of today's dirty reactor methods will be consigned to history of course.

In any event our uranium fission production will only last around 300 or so years, a mere drop in the ocean of time, and our planet is big enough to handle it's residues with ease.