Water + Sunlight = Solar Hydrogen
by Jeremy Elton Jacquot, Los Angeles on 08.17.07
We've often heard the media and government officials talk up the potential for a future hydrogen economy to revolutionize the way we consume and produce energy. And while we've seen some promising applications of hydrogen as a fuel source in the last few months, it still seems very unlikely that we'll ever see a hydrogen-based energy market on the scale that some are envisioning. That's not to say that some scientists aren't still trying to gradually make this a reality: Craig Grimes, a professor of electrical engineering at Penn State University, has just announced that he and his team are close — in their words, "only a couple of problems away" — to developing a cheap, viable photoelectrolytic technology, that is one that would split water into hydrogen and oxygen by using sunlight.
While most current hydrogen production processes split hydrogen from natural gas — an inefficient technique that consumes energy and produces greenhouse gases — Grimes' method would rely on thin films made of titanium iron oxide nanotube arrays that could split water under natural light. According to Grimes, this method is much more eco-friendly since it only requires the natural energy of sunlight and doesn't produce GHGs.
The researchers already knew from previous trials that titanium oxide offered superior charge-transfer properties and corrosion stability, making it an ideal candidate for durable, inexpensive solar cells. Having used ultraviolet light to test earlier versions of their nanotubes — which only contains about 5% of the solar spectrum's energy — Grimes and his colleagues were keenly aware that they would need to find a way to harness a larger portion of the visible spectrum to make the nanotube arrays more efficient and viable.
Using a form of iron called hematite — a low band gap semiconductor material — they were able to capture a much larger portion of the solar spectrum in their arrays. In their recently published study, they reported a photoconversion rate of 1.5%, the second highest rate ever achieved using an iron oxide-related material.
They are now focusing on optimizing the nanotube architecture to obtain an efficiency closer to the theoretical maximum for materials with hematite (around 12.9%). Grimes is certainly hopeful about the prospects for his group's technology to transcend other production methods: "As I see it, we are a couple of problems away from having something that will revolutionize the field of hydrogen generation by use of solar energy."
Via ::Penn State Materials Research Institute: Revolution in Solar Hydrogen on the Horizon (press release)
See also: ::Trading Carbs for Hydrogen, ::Driving in Circles: Hydrogen Cars Close to Production at Ford
How can you have a hydrogen "economy" when it's as freely available as sunshine?
The Sun is a big hydrogen fusion reactor. :-)
"How can you have a hydrogen "economy" when it's as freely available as sunshine?"
Feel free to manufacturer your own hydrogen extraction, storage, and utilization systems.
Other people will most likely wish to rent/purchase theirs.
That sort of thing an economy doth make....
I don't know the answers but out of personal interest I have a question. The idea is to recreate the natural effect of lightning in a closed system in order to induce electrolysis, and produce hydrogen.
What if we started with a closed system of water.
Then separated the system with a layer of glass
Then electroplated the the layer of glass with thin titanium oxide.
Then darken one side of the system so that the glass is dark, and completely resistent to light infiltration.
Then focused solar light energy on one side of the glass. LIke the childhood trick of starting a fire with a magnifying glass.
Now there is a temerature differential which would engage a natural force toward homeostasis
Would the resulting excitement of neutrons on the hot side create friction, resulting in static electric discharge, creating electrolysis effect sepatating the hydrogen from the oxygen?
Also what if the two sides of the water system were separated by an air gap which might conduct the static charge better?
"Would the resulting excitement of neutrons on the hot side create friction, resulting in static electric discharge, creating electrolysis effect separating the hydrogen from the oxygen?"
No. Neutrons do not excite, this is not a nuclear reaction, perhaps you mean neutral molecules? In any event, a thermal gradient does not produce electrolysis.
"Also what if the two sides of the water system were separated by an air gap which might conduct the static charge better?"
An air gap is an insulator, it doesn't conduct anything.