As far as hydrogen storage goes, 2 different tanks are available through

Praxair at:

http://www.praxair.com/praxair.nsf/AllContent/
B2973104A60BF94685256CE3007BBAEF?OpenDocument

&URLMenuBranch=876DC39B3DED2AF28525706F005863A7

The pressure in the tanks is 2000 Pounds per square inche gas (psig).

The sizes are 65 ft3 and 195 ft3. I also know that I have rented a small

hydrogen tank from Lynde welding supply before with similar dimensions.

The cost for the hydrogen is at $15 for 100 ft3.

When you consider the rate of use there is a diagram that shows the

usage rate of these tanks on a much larger fuel cell at

4 Hours for the 65 ft3 tank & 11.5 Hours 195 ft3. The diagram is located at:

http://www.fuelcellstore.com/products/
ballard/cylinders.html

Since the Coleman fuel cell they are using has a much higher usage rate

than the fuel cell I have mentioned in this thread it may be possible

to get 2-3xs the time usage on each tank.

Goodnewsboy very good point on the dangers of hydrogen I have scrounged on

the internet and found a couple of websites regarding gas

monitoring instrumentation. I know from experience that hydrogen

is dangerous, and I mean hey remember the Space Shuttle Columbia?

Also nice point on the need for steady/no spike usage of fuel cells,

I hadn't heard it put that way.

Btrayfors as far as watt to amp conversion math is

12 watts/12 volts = 1 amp

12 watts/24 volts = 1/2 amp

200 watts/24 volts = 8.33 amps

200 watts/12 volts = 16.66 amps

400 watts/12 volts = 8.33 amps

Btrayfors you just take your math a step further. However converting

24v to 12v would likely have a 10% loss in the conversion.

Best Regards,

Windinthesails