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

[gary]

In a 13 March 2019 article 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.

Originally Posted by Maria Gallucci, IEEE Spectrum

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 system can convert 15 percent of the solar energy it receives into hydrogen, the team says. That’s a significant leap from 0.1 percent efficiency they first achieved 10 years ago.

Originally Posted by Maria Gallucci, IEEE Spectrum

However, Martens’s lab was tight-lipped about its technology. Tom Bosserez, a post-doctoral researcher, declined to disclose any specifics, citing intellectual property concerns. He says only that the lab specializes in “catalysts, membranes, and adsorbents.”

“Using our expertise in this area, we were able to develop a system that is very efficient in taking water from the air and splitting it into hydrogen by using solar energy,” Bosserez wrote in an email. Asked about some of the engineering challenges they faced during a decade of development, he says, “The most difficult part is getting the water out of the air.”

Academic papers offer scattered clues about the technology, though Bosserez says their research “goes beyond what we publish.” In recent years, the engineers have studied the efficacy of a variety of materials, including porous, multi-junction silicon solar cells with “micrometer-scale pore dimensions”; thin-film catalysts made from manganese (III) oxide; and a poly (vinyl alcohol) anion exchange membrane involving a potassium hydroxide solution and nickel-based catalysts.

Full story here :-
https://spectrum.ieee.org/energywise...oduce-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 (Julian)]

Originally Posted by skysurfer

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%".

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 (Marc)]

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

[bojan]

Originally Posted by julianh72

.....r—and has a rated power output of about 210 watts."
.

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

[glend (Glen)]

Originally Posted by multiweb

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

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

[Sunfish (Ray)]

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 (Julian)]

Originally Posted by glend

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

It's called an Air Conditioner!