For the most part the hydrogen fuel cell is way beyond my ability to comprehend. That said, from what I have read, the oxygen comes from the air and the hydrogen is stored in a tank in the car. Combustion between hydrogen and oxygen is triggered by electricity supplied by lithium batteries like those used to power cell phones and laptop computers. When the process completes, energy is released and the byproduct is H
2O. I'm assuming that the energy is in the form of electricity. Ask Honda how it works or lease their new model at $600.00 per month for 36 months.
Right now the only two drawbacks are (1) no hydrogen fill stations (there were no gas stations when Henry Ford produced the first model T) and (2) the lithium batteries are subject to catching fire!
This algae deal exists in theory and practice but is not economical as yet - see "
http://www1.eere.energy.gov/biomass/pdfs/biodiesel_from_algae.pdfIt is a way to generate biomass to be used in making bio-diesel. It would be a substitute for diesel fuel not gasoline.
Already stealing french fry grease is an increasing crime problem as bioconversion becomes more common.
The days of free grease is over. My money is on "converting diesel engines to run on straight veggie oil" Why buy new or used grease and convert it to biodiesel every time the tank runs out when you can have a one time engine conversion expense and then run Crisco, canola oil, Mazola or whatever is handy. If you buy the biofuel from a dealer you won't be saving enough to be worthwhile.
My wife convinced me that I was crazy when I got the bio bug back when diesel hit $1.20 per gallon!
All I can do at this point is say, "I told you!" That don't cut it when diesel is $4.59 / gal.
Most of the savings now are in home brew jobs that carries no tax.. When all is said and done, the government will find new ways to tax you so you still won't save anything.