[citation][nom]TA152H[/nom]This sounds horrible.The basis for life is water. So, we want to consume it by the billions of gallons every day. Then, this house will have pure oxygen around, and pure hydrogen, which is volatile. Presumably, the hydrogen would escape at some point, and the Earth can not keep hydrogen atoms, so it would leave our planet, never to return. Something seems wrong. We're complaining about not enough drinkable water, and then we want to liberate from the earth the hydrogen contained in it. When you consider how many people live in this world, if you're pulling down hundreds of millions of gallons of water a day, you don't think there's going to be some climate change from all this loss of water over a period of time? The only thing is, it's not clear if the water is reconstituted. If it is, no problem, but if it's lost, it's insanity.[/citation]
This just makes my head hurt. I'm convinced you're complaining just for the sake of complaining.
It's a danged fuel cell. We've been using them for decades and a basic 5 minute internet search would have taught you that. They're hardly anymore dangerous than any of the other energy sources you have pumped into your home already. And even if you were scared of a hydrogen explosion for some reason, you can always put it in a shed out back and transmit the electricity via wiring into your house (which is one of the handy things about electricity, you can transmit it on wires).
The water is disassociated into H2 and O2 in the 'leaf' and recombined in a fuel cell back into .... WATER. No water is lost. If you didn't recombine the H2 and O2 back into water, it wouldn't generate power. In fact, the water recreated in the fuel cell is potable solving your other worry over drinking water (e.g space shuttle fuel cell system).
Finally, even if we did 'lose' 100 million gallons of water a day through some unspecified Illuminati Reverse Vampire process it'd take us about billion years (based on the earth being 0.023% water by mass) for us to use all the water on the planet (at which point the sun will have made the planet unlivable anyway). If you're concerned about us running out of water after a billion years of use, I can't imagine how worried you are about running out of oil in a few hundred.