Nanoptek Combines Sunlight and a Nanostructured Photocatalyst to Produce Cheap Hydrogen
by Jeremy Elton Jacquot, Los Angeles on 02. 4.08
Image courtesy of Nanoptek, Inc.
The Massachusetts-based energy startup has developed a new process for producing hydrogen fuel from water using just sunlight and a proprietary photocatalyst. Reporting in Technology Review, Kevin Bullis describes its main advantage as being two-fold: it is "cheap enough to compete with the cheapest approaches used now, which strip hydrogen from natural gas, and it has the further advantage of releasing no carbon dioxide."
Nanoptek's technology centers on the use of titania, or titanium dioxide, a relatively cheap and abundant material, to absorb solar energy; according to John Guerra, the startup's founder and CEO, its engineers were able to modify the material so as to enable it to absorb more sunlight, rendering the process of splitting water to make hydrogen much more cost-effective.
To boost its absorption efficiency, Nanoptek's engineers used a technique often employed by the semiconductor industry to "strain" the titania; chip makers have long relied on this method to alter a material's electronic properties - choosing either to press together or pull apart its atoms to obtain the desired result. Guerra explained that less energy is required to split water when titania's atoms are pulled apart, allowing for the use of both high energy UV light and low energy visible light. The company's engineers deposited a coating of titania on dome-like nanostructures to get the atoms to pull apart.
Here is how Nanoptek's website describes the process:
"Nanoptek has developed a titania photoelectrode that is low cost, has a long lifetime, and higher efficiency in converting sunlight into hydrogen. Nanoptek has developed a way to use nano-structures (as shown in our logo) to cause large local nano-scale stresses in the titania. This stretches the titania crystal lattice so that electrons are held less tightly in the lattice and so can be knocked out of the titania with light of lower energy, meaning visible. These electrons then drive the hydrogen production. This is known as “bandgap engineering” and causes Nanoptek’s titania photocatalyst to be photoactive well into the visible blue, and so is 6X more efficient in sunlight than native titania, which requires the sparse ultraviolet (UV) part of the solar spectrum."
Unlike processes that rely on natural gas or electrolysis, which are more costly and inefficient, Nanoptek's approach is cheap and produces no carbon dioxide emissions. By being located close to its customers, the company's technology would also significantly cut back on transportation costs. In addition to supplying fuel-cell vehicles, Nanoptek's process - if it proves to be as cheap and efficient as Guerra claims - could be used for the nighttime storage of solar energy.
Via ::FuturePundit: Solar Material Makes Hydrogen From Water (blog)
See also: ::E. Coli: The Next Big Source of Hydrogen Fuel?, ::Water + Sunlight = Solar Hydrogen
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this is totally awesome, i hope this kind of technology can continue to be developed, unhindered.
Sounds cool, but what is the efficiency? That is really going to be the key as direct to hydrogen systems have been developed before using superheated water (heated by concentrated sunlight) and a platinum catalyst.
But isn't Hydrogen less efficient than straight-up electricity? Are there applications better suited to hydrogen use vs. electricity?
Hydrogen IS less efficient than electricity when you use electricity to produce it (electrolysis). But this process does not use electricity as its energy source but uses the sun's energy directly instead.
The clever bit appears to be that the process is very efficient so requires much less energy from the sun than would be the case without this process. Therefore you can produce much more hydrogen, apparently to the point that the process is productive to a worthwhile degree.
The problem with using any energy source in a moving vehicle is that you have to be able to store it. Gasoline/diesel are very good in this respect because they are easy to store and very energy dense. Electricity is pretty poor - batteries are heavy and inefficient (at least on the basis of current technology), and take quite a long time to charge.
Hydrogen potentially is a better fuel as far as storage and distribution, but up to now has not been energy positive - this process looks like it might address that issue if what they say is true.
A lot of people discount the potential of.... methane. It is currently our best way of storing hydrogen. Just take hydrogen from the Nanoptek concentrators and combine it with Carbon (from wherever is cheapest, probably coal for a while) and you have methane.
Methane can be stored as ANG and burnt in conventional engines with substantially lower GHG emissions.
I believe the Nanoptek process is 30% efficient. I'd do the math as to how much methane you could get per m^2/day.... but I'm too tired right now. Anyone else care to oblige?
Why would we use clean sunlight to make CO2 free hydrogen from water, just to combine it again with carbon to make a less efficient fuel that produces CO2?
I believe hydrogen in ICE engines is three times as efficient as gasoline. I'm not sure how that compares to methane, but I know methane isn't three times more efficient than gas. If we use fuel cells it will be even more efficient.
If you can get a copy of RMI's Winning The Oil End Game you'll see some pretty good options for ultra-light-weight vehicles that use either compressed hydrogen or hydrogen stored in a metallic compound (developed by Stanford Ovshinsky).
Pure hydrogen is the end goal. I don't see how adding processes would make it more efficient?