What do I need to make enough hydrogen gas to power a gas lawn mower for 15 minutes?
I want to be able to store it in a 20 lb propane tank which means I need to compress it. (That's the average size tank that mounts on a small trailer)
H2 at the maximum pressure the tank can hold has a density of .075 pounds/cf. This means you can get .05 pounds of H2 in the tank. H2 has 50,000 BTU/lb so you can store 2500 BTU's (if you fill the tank with propane, it will hold 400,000 Btus some 150 times as much energy). This amount of H2 is equal to 2.5 ounces of gasoline. A lawn mower will use .5 ounces per minute or more, so your tank will last 5 minutes.
You will need a compressor to put the H2 into the tank. H2 compressors are very exotic and the smallest ones cost $10,000. Looks like you will need some cash to get started...
