There is ABSOLUTELY no substitute for the gasoline base fuels we have for our mobile transport - especially aircraft and automobiles. The energy carrying and energy releasing properties of 8 to 12 carbon atom alkane hydrocarbons are simply the best.
Hydrogen is a nice fuel, but very difficult to manage. Storing it as a hydride, or adsorbed on some material will give you the same problems as battery powered cars - weight, space and low range.
Gas stations that make hydrogen on site are a nonsense, especially when they talk about using petroleum as the raw material. Where does the carbon go ? Back to a power station so they can burn it to make the buckets of additional energy needed ? Then the carbon goes up the stack as CO2 ?
Do some simple arithmetic on my small local gas station.
Lets say he has 3 customers filling at any time for 8 hours per day, 7 days per week, and none in the other 16 hours. It takes about 5 minutes to fill a tank, and I use a very modest 40 litres/week.
So that gas station supports 672 customers like me, and uses 26,880 litres/week. (A bit less than one full tanker per week).
The heat of combustion of hydrogen is 33,887 cal/gram
The heat of combustion of n-octane (gasoline, more or less) is 11,500 cal/gram
Lets say the gas station keeps the hydrogen in its most dense form. Liquid hydrogen has a specific gravity of 0.0709 at -253 centigrade. Gasoline is near enough 0.8.
So if the conversion efficiency (fuel energy to power on the road) for a hydrogen fuelled automobile is the same as a gas powered one, the gas station must make an average 26,880 * (11,500/33,887) * (0.8/0.0709) = 102,930 litres of liquid hydrogen per week.
That sounds absurd. Lets say the hydrogen engine is 10 times as efficient as the gas one. Now the gas station has to make only 1,470 litres/day. If he wants to store 2 days worth to cater for downtime while his plant is serviced, he has to store 2,940 litres or 648 Imp. gallons. And he will need BIG "No smoking" signs.
That bit of arithmetic is extraordinarily optimistic in many ways. By the time you go to hydride storage, then add in the energy requirements needed to crack the H20 and compress it, you will strike insurmountable problems.
Solar cells can't drive practical automobiles (as we now know them). Maximum power solar power flux is (I think) about 1kw/ sq metre. If we say 50% conversion efficiency to power on the road, my little automobile, pottering along with granny driving it at a mere 10kw power on the road, airconditioning off, will need a 2 x 10 metre solar panel on the roof. It will need auto spoilers on it if granny goes too fast coasting downhill.
Solar panels will no longer be reasonably cheap to make when the raw materials (purified silica, metals, glass and plastics) have to be made with the power produced by solar cells, and without the benefits of petroleum and its byproducts.
Metals (Steel, Aluminium, Copper etc), while themselves a depleting resource, will become expensive commodities as the things which make them from their ores (coal, oil, power) dwindle. (Notice how Aluminium smelters like to be near hydro power ?)
Hydroelectric power is good, but limited. Does serious damage to the downstream area. Floods a few people.
Nuclear (fission) energy is no use in airplanes and automobiles (except via the hydrogen route), and is understandably not too popular.
Wind and tide power won't drive airplanes and automobiles (Blaniks and the like will never be a people mover)
Iceland would be a good property investment from an energy cost point of view (thermal).
Nuclear (FUSION) has some promise, except they can't do it.
So all you lucky people swanning around in your Boeings, Airbusses, Harriers (have I missed anyone important ?), enjoy your flight. Gasoline, Avgas and Avtur resources are finite. They will run out. The end is nigh.
But I think you have time to get home before the fuel runs out, and have a G&T. I am about to pour my third.
ET
[This message has been edited by EchoTango (edited 13 January 2001).]