Posted on 01/31/2005 11:44:25 AM PST by anymouse
Pure hydrogen fuel is non-polluting. Current methods of extracting hydrogen, however, use energy derived from sources that pollute. Finding ways to use the sun's energy to split water to extract hydrogen would make for a truly clean energy source.
Several research efforts are using materials engineered at the molecular scale to tap the sun as an energy source to extract hydrogen from water.
Researchers from Pennsylvania State University have constructed a material made from titanium dioxide nanotubes that is 97 percent efficient at harvesting the ultraviolet portion of the sun's light and 6.8 percent efficient at extracting hydrogen from water.
The material is easy to make, inexpensive, and photochemically stable, according to the researchers. The 97 percent efficiency is the highest reported, according to the researchers. There is one catch -- only five percent of the sun's energy is ultraviolet light.
The researchers are working to find a way to shift the response of the nanotube arrays into the visible spectrum.
The key to making titanium dioxide nanotubes that efficiently harvest the energy from light is controlling the thickness of the nanotube walls, according to the researchers. Nanotubes 224 nanometers long with 34-nanometer-thick walls are three times more efficient than those that are 120 nanometers long with 9-nanometer-thick walls.
The researchers made the titanium dioxide nanotube material by mixing titanium with acid and electrifying the mixture, which caused the tiny tubes to grow, then heating them to cause the material to crystallize.
The material could be ready for practical use in two to five years, according to the researchers. The work appeared in the January 12, 2005 issue of Nano Letters.
Storage was solved quite a while ago.
Sodium borohydride
http://www.millenniumcell.com/technology/index.html
"the low energy density"
Depends what you're comparing it to. You're right if you're talking about other hydrocarbon fuels, but H2 has an advantage in energy density (>3000 Wh/l) over Ni/Cd (~400 Wh/l) and even Li/C-CoO2 (~1500 Wh/l) batteries. So if they application is to generate energy for something like a laptop or a video camer, then there might be a market. However, there are some other issues like cost-effectiveness that still make it a tough sell.
You are correct, I was thinking in terms of hydrocarbons. There is a cost factor for electrical apps though- once you've factored in the energy used to produce, transport and store the hydrogen the advantage over batteries is probably diminished quite a bit. So it all comes down to cost- if (when) you can make a fuel cell that's cheaper than a battery then we'll see a revolution in portable electronics. That's the real ticket here- for transport fuel I don't think hydrocarbons will go away until someone creates a nuclear reactor that's small enough, cheap enough and safe enough to put under the hood of a car.
The claim out of Carthage Missouri is that they have their process at 85% efficiency, meaning they can "refine" turkey guts into oil and end up with a "net plus". If they can engineer this down, with a discreet input (manure, municipal water-waste, medical/slaughterhouse waste) their exists the possibility of colocating next to diesel power plants and generating electricity.
I wonder if we could get their hot air classified as a "greenhouse gas?"
Actually, it's 97% * 5% = 4.9% efficient.... ;-)
Note: this topic is from 1/31/2005.Thanks anymouse.
Researchers from Pennsylvania State University have constructed a material made from titanium dioxide nanotubes that is 97 percent efficient at harvesting the ultraviolet portion of the sun's light and 6.8 percent efficient at extracting hydrogen from water.
Note: this topic is from . Thanks anymouse. Re-ping from 7 years ago.
Re-ping what you sow?.......................
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.