New solar cell cuts out the middle man, harvests hydrogen from water

Some Penn State researchers are taking a cue from nature and have built the first solar cell that can effectively split water to harvest the hydrogen. While the technology and efficiency of electricity-gathering solar cells has been humming on nicely, cells that can pull hydrogen out of water directly (instead of using solar-harvested electricity to do it) have found that the catalysts conducive to separating hydrogen and oxygen are usually pretty good at putting the two gases right back together again. The folks at Penn State have now developed a process that more closely mimics the photosynthesis process in plants, and while we won't pretend to understand all the nitty gritty of dye usage and other such nonsense, we do know that such a system could eventually attain 15% or so efficiency, providing a nice and clean way to gather power for that fuel cell car of the future.

[Image courtesy of MTU.edu]

[Flashpoint @ Feb 18th 2008 9:48AM]

How long does it take one of these cells to generate 1.21 Gigawatts?

[Warhorse @ Feb 18th 2008 10:45AM]

Don't be silly, Mr. Fusion takes care of all of that for you now.

[AboveUnrefined @ Feb 18th 2008 11:56AM]

Jigawatts! Doc, What the Hell is a Jigawatt?

[Abuzar @ Feb 18th 2008 9:59AM]

Are they using cyanobacteria?

Read The Green Trap by Ben Bova.

[Justin B @ Feb 18th 2008 10:08AM]

Wat. Cyanobacteria undergo photosynthesis. In which the electrons are removed from water to create Hydrogen protons and oxygen. The hydrogen protons are necessary for the cell's survival.

[Abuzar @ Feb 18th 2008 11:17AM]

Yeah the plot of the book was the one guy managed to genetically engineer cyanobacteria so they broke down more water molecules then they needed to survive.

[Sirius @ Feb 18th 2008 10:17AM]

Photosynthesis huh.. so we can also get glucose on tap in our fuel cell cars? :D

[bi0hazard @ Feb 18th 2008 10:50AM]

Aren't people fat enough already?

[qwho @ Feb 18th 2008 10:53AM]

WE ARE!

[CosterMonger @ Feb 18th 2008 11:03AM]

it runs on water man!

[Superprime @ Feb 18th 2008 11:14AM]

"we do know that such a system could eventually attain 15% or so efficiency"
Translation:
"This doesn't really work but we'd sure like some funding"

Universities are the number one source of projects that only suck money and don't go anywhere.

[sitruc @ Feb 18th 2008 12:25PM]

Intel wishes that were true.

[greymullet @ Feb 18th 2008 1:25PM]

15% is GOOD.

[Bill @ Feb 18th 2008 12:18PM]

Photosynthesis is nowhere near 15% efficient.

Not to mention we don't have any practical way to transport or store hydrogen (check how much energy it takes to compress to 700 bar, the pressure fuel cell vehicle manufacturers want to use)

[Sean O @ Feb 18th 2008 2:19PM]

Associating hydrogen exclusively as automobile fuel is small minded. First off, I do not believe hydrogen fueled cars will be in our future. We will all be using electric cars with nano-tech super batteries (think electric Hummers that can go 400 miles on one charge). The issue is generating electricity in a clean, cheap, and renewable manner. Hydrogen, created in a remote location (like a solar farm in the ocean) could be sent to traditional power plants via pipelines that are already set up for burning oil and natural gas. There are also other ways being developed to store hydrogen, such as titanium polymers, and coal powder.

[Joe Maki @ Feb 18th 2008 1:30PM]

>> One reason for the difficulty is that once produced, >> hydrogen and oxygen easily recombine.

So outside of hydrogen production couldn't this also be used for desalination and purification of water?

[Reader @ Feb 18th 2008 1:57PM]

Hydrogen will most likely die off with the rise of more efficient batteries and supercapacitors. Might be cool for other uses though (like a paintball shop).

[0150r @ Feb 18th 2008 2:56PM]

Hydrogen at a paintball shop? Paintball markers use compressed air or CO2. There is one that uses propane, but hardley anyone uses it. Many fields do not allow the propane powered markers because of insurance issues and legality (some stays may classify the propane marker a firearm). I highly doubt anyone would use hydrogen for paintball.

[Reader @ Feb 18th 2008 3:24PM]

Just noticed what I did... It's nitrogen/compressed air we use not hydrogen. What a fool I am. Been a while since I've been paintballing.

[0150r @ Feb 18th 2008 2:57PM]

stays = states

[kyau1 @ Feb 18th 2008 8:54PM]

For a large university and some intellectual superminds, they could have paid a graphic designer (student) to create a nice diagram. But the obviously chose the imagery from lead researcher's daughter's 8th grade science project.

Great idea if it works though.

[jamesFF @ Feb 18th 2008 10:20PM]

Solar powered rockets, COOL!!

[Fried bourbon n coke @ Feb 19th 2008 7:43AM]

what about a car or house that has such a system intrinsically built in... your car sitting in the sun could be recharging its batteries by re burning its harvested exhaust. Or, more interesting, using the conversion back to power up its hydrogen cell for burst energy such as start up of systems and environment cooling/heating. The way it reacts could change the way the vents open or close and curtains close or open making your house/vehicle react almost like it is alive.

[Dr. Kenneth Noisewater @ Feb 19th 2008 12:27PM]

So 15% efficiency means what? 150ml of hydrogen per liter of water? 15% of a mole of H2 per mole of H20?

Maybe I should RTFA... :p

[Meower68 @ Feb 19th 2008 1:20PM]

Direct, unobscured sunlight puts about 1 kW of energy on a sq meter. A kilogram of H2 is approx. equivalent to 36 kWh of energy. At 100% efficiency, 36 sq meters of solar collector could make 1 kg of H2/hour.

At 15% efficiency, you'd need about 6.5 hours for 36 sq meters of this stuff to make 1 kg of H2. 1 kg of H2 has about the same energy content as a gallon of gasoline.

Most of your commercially available PV panels top out at 20% or less. A hydrolyzer (using electricity to split water) is typically 50% efficient or less. So, best case, modern PV and a modern hydrolyzer would be 10% efficient (sunlight -> electricity = 0.2x; electricity -> hydrogen = 0.5x; 0.2x * 0.5x = 0.1x), total.

This would go from sunlight straight to hydrogen, without needing the sunlight -> electricity -> hydrogen process. Such things have been developed before, but they were < 1% efficient.

[Bigtimes @ Feb 19th 2008 12:29PM]

Maybe I'm missing something here, but can't we do this exact same thing by just running a regular solar cell's positive and negative leads into water and collecting the hydrogen and oxygen from the terminals?

[jdkchem @ Feb 19th 2008 1:26PM]

Yes. However, it is extremely time consuming. From http://www.switch2hydrogen.com/h2.htm
"You can produce your own Hydrogen from electricity using either common "household current" or directly from solar cells so your energy cost is zero. It does however take a substantial amount of time to produce sufficient Hydrogen to fill even a small tank.
As an example, it takes over 2 days of our generator running at full power, 24 hours a day, to fill our smallest "short range" tank."

[Bigtimes @ Feb 20th 2008 9:26PM]

I wonder what the efficiency difference is.

[Kent G. Budge @ Feb 19th 2008 1:20PM]

"...the catalysts conducive to separating hydrogen and oxygen are usually pretty good at putting the two gases right back together again."

Well, that's true of all catalysts. It's basic thermodynamics.

[bour3 @ Feb 19th 2008 3:17PM]

So, according to that illustration up there, the roots of a tree serve only as an anchor?

These oversimplifications, they simplify things to the point of, of, simplification.

[jrtallen @ Feb 19th 2008 8:37PM]

Correct me if I', wrong, but a British company called Hydrogen Solar invented the same thing about 3 years ago, didn't they?

www.hydrogensolar.com

[Kent G. Budge @ Feb 23rd 2008 1:47PM]

"So 15% efficiency means what? 150ml of hydrogen per liter of water? 15% of a mole of H2 per mole of H20?"

I think it means that 15% of the solar energy striking the cell is captured as chemical energy of reduced hydrogen.