Effeciency of photolysis versus electrolysis

[RVonse]

I was just watching a PBS documentary and they stated that the approximent effeciency of electrolysis (changing water into hydrogen and oxygen) was about 1.3. I guess that would mean it takes 1.3 watts of electricity to yield 1 watt of hydrogen if it is burned. Meaning after the hydrogen is burned you get your 1 watt of energy back plus the original water. So far all this makes sense to me.

 

Then the program went on to say that the photolysis process nature does in leaves is much more effecient but that so far, no one can duplicate this process to manufacture hydrogen directly. But if a break through comes in this photolysis it would solve the energy crises mankind faces today.

 

So what I am wondering is just how effecient is the process of photolysis anyway? Surely it can't be that much better than 1.3 to 1? I can not imagine a process that would yield more energy out than you put in. I had always thoguht the energy driving photolysis came from the sun and that was an equiavalent amount of electrical energy similar to electrolysis. Is this not the case? What am I missing here?

[insane_alien]

1.3? you can't infer anything from that. we don't know if its a ratio a percentage or space monkeys with evil shadows that have cups of tea.

 

Watts don't make much sense as its a unit of power. Joules would be more appropriate.

 

Did it give you a value for photolysis? this would make it easier to make a guess as to what they hell they're on about.

[RVonse]

I think their words about the electrolysis conversion is that 1.3 units of electrical power only yielded 1 equivalent unit of hydrogen envergy. Another words if the electrical energy was instead powering a resistive element it would heat 1.3 times as much as burning the hydrogen that was converted. Personally, I don't think that sounds so bad. But they said its not good enough effeciency to provide practical hydrogen conversion.