There's still a lot of problems to be overcome with using hydrogen, or swamp
gas, or biogas... or any other non-petroleum based fuel... in vehicles.

First and foremost, there's the energy density problem. All of those gases
have far less energy content per unit volume than any petroleum product.
Ergo, it takes lots of gas to create the same horsepower. Where are you
gonna put all that gas in a vehicle? You have to compress it and put it
into some kind of storage tank. Compressing anything takes more energy.
How are you going to create the hydrogen or other gas? You don't just
gather it up. It has to be manufactured, which takes more energy. Some
methods allow you to use passive energy such as solar, but take a long time
to generate the quantities required to be useful. Other methods require
energy input from... petroleum fuels... to create the "clean" gas. Ack.

Second, with hydrogen there is a huge storage issue. Hydrogen molecules are
tiny, the tiniest molecules around. They're even smaller than helium
molecules. Ever watch a helium balloon deflate over days? It leaks THROUGH
the balloon, not out the knot. Same thing would happen to a pressurized
hydrogen storage tank. Gradually the molecules would seep out and the tank
would empty. Not good. So, people are working on storage techniques using
metal hydrides to bind with the hydrogen, then release it upon demand.
Unfortunately, the "release" part requires more energy input.

Third, let's assume that we're talking about using a fuel cell approach to
convert hydrogen into energy. Fuel cells produce electricity. This means
electrical motors for a boat, and possibly larger battery banks. Ever
priced 100hp electric motors, not to mention 300hp ones? Wonder what the
power plant for a trawler consisting of a 200kW fuel cell, a bank of
batteries, two 100Hp motors, the associated electronic controllers, and the
huge inverter(s) for AC consumption onboard might cost? Ack. How about
what it would weigh?

Fourth, let's assume that we're not generating our own hydrogen or biogas or
swamp gas on our boats. How long do you think it will be before every
marina and fuel dock in cruising waters has a hose marked "hydrogen"? I
think the longterm answer will be some sort of sequential machine: hydrogen
generator feeds fuel cells which feed electric motors, or something. You'll
make your own hydrogen (or swamp gas, or ...) on the fly using sea water,
sunlight, and Special Sauce, then feed the gas you produce right into the
"engine". Hopefully, the "Special Sauce" will be cheap and available.

If I ever get into the cruising game, and I intend to - thus I'm lurking in
groups such as these - I'll try to employ alternative fuels. I just don't
think affordable diesel is going to last all that long into the future.
But, per my research, practical alternative fuels are ways away. Don't
believe me? Go to some of the web sites that promise such wondrous
technology. See how many have a commercial, viable product. Folks like to
talk about what can be done, but there are a LOT of technological and
economic hurdles yet to overcome before these alternative fuels are a viable
reality.



"bowgus" wrote in message
...
To clarify ... hydro, wind, solar energy could be used to create the
hydrogen. And it's looking like natural gas, swamp gas, you name it may be
used as well without the combustion side effects associated with getting
energy from gas.

The sticky point with hydrogen is that it takes so much energy to
produce. Where are we going to get all this energy, which we're
already
short of?