Prototype solar panel claimed to produce 250 litres of hydrogen/day from air moisture

[gary]

In a 13 March 2019 article (https://spectrum.ieee.org/energywise/green-tech/fuel-cells/solar-panel-prototype-splits-water-to-produce-hydrogen)at the Institute of Electrical and Electronics
Engineers (IEEE) web site, Maria Gallucci reports on a claim by researchers
at Katholieke Universiteit Leuven in Belgium that they have produced
a prototype solar panel that takes moisture from the air and splits it
directly into hydrogen and oxygen molecules. Rather than use
electrolysis, this is referred to as direct solar-splitting technology.





Full story here :-
https://spectrum.ieee.org/energywise/green-tech/fuel-cells/solar-panel-prototype-splits-water-to-produce-hydrogen

[skysurfer]

250 liter gaseous H2 ?
That is a tiny bit.

Here some basic high school thermochemistry.
That is about 10 mol = 20 grams with an energy of 10*286 kJ/mol = 2860 kJ.
2860kJ / day (the 250l is a day yield) = 2860000 J / 86400 s = average power of 35 W.
The size of the panel is 1.65m * (assumed ?) 1m = 1.65m2 which collects 1650W when exposed directly to the Sun.

Efficiency = 35/1650 = 2.2% and not the "15%".
Electrolysis powered by the same solar panel is probably better.

But it is a first step to more.

[julianh72]

To be fair, there are at best 12 hours per day of sunlight (averaged over the year), and a couple of hours per day may not have sufficient intensity to reach operating requirements (and that's before we account for clouds etc), so the overall efficiency is probably 2 to 3 times higher than your estimate.

The article states:

"The solar panel measures 1.65 meters long—roughly the height of a kitchen refrigerator, or this reporter—and has a rated power output of about 210 watts."

The Solar Constant is about 1.36 kW/m2, so if their unit is producing 210 watts of usable hydrogen energy (released by combustion), that is not too far off the claim of 22% efficiency.

They'll need to produce more information to back up their claims before it becomes clear that generating hydrogen to burn for energy (or power a fuel cell?) is a better solution than direct solar to electricity. At the end of the day, a lot will come down to overall system efficiency, and the relative costs of storing energy in gas tanks or batteries.

[multiweb]

Now solar panels that make water out of thin air that would be cool. :)

[bojan]

Not sure stated 210W is for solar panel as such (actually, that is quite average) or final output (in a form of hydrogen)?

[glend]

It's called a Stillsuit, invented by the Fremen of Dune.

[Sunfish]

Very interesting first step. Let’s have some on every garage.

If it was a suit there would be a little extra energy from the methane and a little less greenhouse gas. Maybe cows could wear them.

[julianh72]

It's called an Air Conditioner!