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Self-Sustaining Solar Reactor Creates Clean Hydrogen
An anonymous reader writes "A mechanical engineer working out of the University of Delaware has come up with a way to produce hydrogen without any undesirable emissions such as carbon dioxide. The solar reactor is capable of using sunlight to increase the heat inside its cylindrical structure above 3,000 degrees Fahrenheit. Zinc oxide powder is then gravity fed through 15 hoppers into the ceramic interior where it converts to a zinc vapor. At that point the vapor is reacted with water separately, which in turn produces hydrogen. If the prototype gets through 6 weeks of testing at the Swiss Federal Institute of Technology located in Zurich, we could see it scaled up to industrial size, producing emission-free hydrogen."
Finally, a source of clean hydrogen.
Gently reply
Am I the only one who gets annoyed when scientific articles use archaic scales like Fahrenheit?
How much energy and other resources will be required to first mine all that zinc and then create the oxide to use in this device? What other costs of the process are being omitted here?
I'm not an engineer, so get out your salt-lick before reading...but, they've developed a "proof of concept" device. I don't know if it's even appropriate to discuss "practical" uses of this device, yet. It's possibly a very expensive way to produce hydrogen and may not be meant to see much light of day outside academic circles.
One interesting feature of the reactor is that, in theory, the zinc oxide byproduct created during the reaction will be re-usable, making the project self-sustaining.
“This is probably the most complex device built by a graduate student in the history of our department,” added Prasad. “If he is successful, one day, we can imagine a huge array of mirrors out in the desert concentrating sunlight up into a large central tower containing a larger version of Erik’s reactor and making hydrogen on an industrial scale.”
So there's "hope", but is currently experimental:
We [they] will measure the temperature and the production of oxygen inside the reactor in real time, which will tell us how much solar fuel or zinc we are actually producing,” Koepf explained.
All of the above from TFA.
PS: I don't reply to ACs.
water ( aka dihydrogen monoxide ) is far less of a concern with respect to the greenhouse effect than CO2 is.
Its far better on the environment to emit water vapour instead of CO2.
The warmer the atmosphere, the longer water vapor will remain gaseous and the higher the saturation point. We're told the atmosphere is already warming and will continue to do so. It seems rather risky to bellow the most dangerous greenhouse gas of all directly into the air in quantities this planet has never seen before.
You're ignoring the effects of atmospheric heating on that cycle. Thanks for the ad hominem as a bonus.
It's not self-sustainable. It's sustained by the sun.
It is no longer uncommon to be uncommon.
Because Pushing-Robot apparently can't read, I've gone and done some investigation myself. From what I've been reading, it seems the most common method is by burning zinc ores or through carbothermal reduction to produce zinc vapor which then is mixed with oxygen to produce a zinc oxide runoff. These generally both produce large carbon output.
Using the device itself to burn zinc ore (in order to produce zinc vapor and additional fuel) will still produce carbon dioxide as a by-product. You need purified zinc to avoid this, and there are no clean purification methods.
The wet chemical process still results in zinc carbonate which needs to be heated to be refined to zinc oxide, releasing the carbon.
Laboratory production by electrolyzing a solution of sodium bicarbonate with a zinc anode produces useful zinc hydroxide and hydrogen gas. However carbon and sodium are released as waste.
Is there a way this can actually be produced without releasing carbon, or is this reactor just shifting the problem elsewhere like so many "green" solutions?
"The true measure of a person is how they act when they know they won't get caught." - DSRilk
If it's solar then the atmospheric heating would have been there anyways.
When our name is on the back of your car, we're behind you all the way!
I know that you're being deliberately obtuse, but for the benefit of any people who may not see through your little charade, I'll point out the key difference between water vapor and the CO2 this technology would be replacing: The half life of CO2 in the atmosphere is nearly a century. The half life of water vapor is a couple of days.
about 14 million tonnes of water evaporate from the oceans every second. I don't think we're going to make that much of a difference.
404: sig not found.
Unless you are being unnecessarily pedantic, the ZnO should be considered as a one-off, sunk cost and therefore this does indeed represent "carbon-free energy":
Zinc-Zinc Oxide Cycle
The reaction regenerates the ZnO at the end of the cycle (reminiscent of a catalyst); therefore, the net reaction is H2O -> H2 + 1/2 O2. So, while the reactor requires some quantity of ZnO to bootstrap itself, very little (or no) additional ZnO should be required to keep it operating. If this particular prototype reactor doesn't fully regenerate & reuse the ZnO, then that is a limitation of the particular implementation and not a limitation of the thermochemical cycle itself.
However, if you were intending to be pedantic in the sense that almost *nothing* can be built without generating some sort of carbon dioxide emission (eg. if you consider wind energy to be "non carbon-free energy" because CO2 is produced during the manufacture of wind turbines), then please accept my opprobrium for your pedantry.