Self-Sustaining Solar Reactor Creates Clean Hydrogen 406
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."
Darn that dirty hydrogen (Score:5, Insightful)
Re:Darn that dirty hydrogen (Score:5, Insightful)
Finally, a source of clean hydrogen.
That is true, but isn't one of the big problems with Hydrogen storing it [wikipedia.org], not just producing it? I mean, don't get me wrong, it is excellent to see that part of this "we want to use hydrogen" problem solved, but a lot more still needs to be done.
Re:Darn that dirty hydrogen (Score:5, Informative)
One reason storing it is such a big deal is because generating it can be expensive. Make hydrogen easier to produce and it lowers the demands on storage.
Re:Darn that dirty hydrogen (Score:5, Interesting)
Hydrogen stored under pressure has a considerably lower energy density compared to hydrocarbons that we use. Hydrogen is great when you look at the energy by weight, but if a tank is sitting in the back of a car, it doesn't matter whether it weighs an extra twenty kilos, what matters is how far a tank can make a car drive.
Like I said, don't get me wrong, I think it is a fantastic breakthrough to have - a cheap, clean and sustainable way to make Hydrogen gas, but a lot of work still needs to be done before we can all whizz around in clean cars and certainly before we have large scale power stations powered by burning Hydrogen.
Having said that, burning Hydrogen makes water, this process turns water into Hydrogen. It would make for a wonderful closed circuit...
Re: (Score:2)
What happened to all those storage schemes that involved Metal hydrides and all sorts of other esoteric stuff. Did any of that end up being useful?
I saw one demonstration where they shot a cylinder with a rifle and all it did was hiss quietly.
Re:Darn that dirty hydrogen (Score:5, Informative)
The biggest hurdle would seem to be infrastructure. It's catch 22, mass production and distribution of H2 requires a H2 market to sell to, and vica-versa. Petrol did not really have this problem, the first generation of car owners bought their fuel in cans from the local pharmacy. The car and car fueling infrastructure evolved together, by the second generation of car owners we had two new major industries led by companies such as Ford and Standard Oil.
So here we are in the 21st century and FF transport is ubiquiotous, the no way a competing technology such as H2 will never gain a foothold with current market fources. It would have to be a cooperative effort between government and industry to deliberatly kill off FF cars, that's already happened with lightbulbs but transport is a much bigger challenge and (for some people) it beccomes as personal as a cowboy's horse.
Re:Darn that dirty hydrogen (Score:4, Funny)
The biggest hurdle would seem to be infrastructure. It's catch 22, mass production and distribution of H2 requires a H2 market to sell to, and vica-versa. Petrol did not really have this problem, the first generation of car owners bought their fuel in cans from the local pharmacy.
Hell, that's an idea! Let's sell H2 canisters at pharmacies.
(ducks)
Re: (Score:3)
H2 gas has around 1/3 the energy density of methane, the largest component of natural gas. Rather than saying "Hydrogen sucks because I can't put it my car," we should be asking, "Can we replace natural gas with hydrogen?" I use natural gas for heating, cooking, and it's increasingly used in power generation. Do we need all new pipelines, or can we use some of the existing infrastructure? I've never heard anyone complain that natural gas is too expensive for the providers to store at various places alon
Re: (Score:2, Insightful)
It would make for a wonderful closed circuit...
For a closed circuit wouldn't we also end up with a pile of zinc oxide?
Re:Darn that dirty hydrogen (Score:5, Informative)
You start with zink oxide. Apparently (not a chemist here) you de-ogygenate it via heat making zink vapor (releasing O2, which is vented) and that zink vapor grabs oxygen from the water, leaving you with your H2 product, and a clean supply of Zink Oxide again.
The byproduct is Oxygen.
Re:Darn that dirty hydrogen (Score:4, Funny)
.. with zink oxide...making zink vapor...that zink vapor....supply of Zink Oxide again.
Are you German, perhaps?
Re:Darn that dirty hydrogen (Score:4, Funny)
Hydrogen stored under pressure has a considerably lower energy density compared to hydrocarbons that we use. Hydrogen is great when you look at the energy by weight, but if a tank is sitting in the back of a car, it doesn't matter whether it weighs an extra twenty kilos, what matters is how far a tank can make a car drive.
Well... one can always mix hydrogen with some carbon to store it, can't one now?
(ducks)
Re:Darn that dirty hydrogen (Score:5, Funny)
No, the obvious, cheap, easy way to store hydrogen is to mix it with oxygen. It makes a really stable compound which we could truck around, or send places in pipes.
Re:Darn that dirty hydrogen (Score:5, Funny)
Re:Darn that dirty hydrogen (Score:5, Informative)
Re:Darn that dirty hydrogen (Score:4, Informative)
Re:Darn that dirty hydrogen (Score:5, Interesting)
Re: (Score:3)
That 2-3x doesn't take into account the tank required to store hydrogren, a battery is self-contained and directly outputs usable electricity. Hydrogen further requries a fuel cell. If stored at a more reasonable pressure, say 300bar/4,500psi lithium ion batteries are on-par/slightly better with hydrogen. If you compare by weight, the weight of the storage tank would be considerable. The higher the pressure the heavier the tank. CNG powered cars only hold ~250bar. LPG (like your BBQ gas bottle) is stored a
Re: (Score:3)
Re: (Score:3)
Re: (Score:3)
Hydrogen stored under pressure has a considerably lower energy density compared to hydrocarbons that we use.
Hydrogen+CO2+energy=hydrocarbons, specifically methane (aka natural gas), and water.
Use nuclear/hydro/solar/wind/whatever for the energy source, and you've got a closed carbon cycle fuel with only fairly minimal changes needed.
Re:Darn that dirty hydrogen (Score:5, Interesting)
Or even use the hydrogen in a Carbon-monoxide/dioxide capture scheme and produce methanol that could be used in today's engines with minor conversions.
The cars would of course re release that carbon dioxide when driving, so it wouldn't really be sequestering.
See syn-gas to methanol process from the 1920's by Alwin Mittasch and Mathias Pier. Or alternatively the newer processes involving a copper catalyst.
Re:Darn that dirty hydrogen (Score:5, Interesting)
Eh? Those have nothing to do with each other. Hydrogen storage is a pain because of density and sealing. At STP, hydrogen is a very low density gas. To get decent energy density out of it, you either have to compress it to ridiculously high pressures, or chill it to ridiculously low temperatures. Di-atomic hydrogen gas molecules are about the smallest molecules that exist. They will leak through anything. A seal which is water-tight and air-tight is not necessarily hydrogen-tight. Couple this with high pressures and you have a major storage PITA.
Unless we discover some sort of hydrogen sponge which soaks up H2 gas and easily holds it at an energy density competitive with batteries and chemicals, I really doubt the hydrogen economy will take off. OTOH if someone can tweak this process so it can convert CO2 + 2 H2O ==> CH4 + 2 O2, then we have a winner. Methane, while not as ideal for storage as a liquid hydrocarbon (most oil wells and refineries just burn it off rather than try to capture and store it), is much easier to work with than H2 gas and has nearly 4x the volumetric energy density.
Long-term, I think alcohol biofuels will win out. Alcohol is nearly as good a storage medium as gasoline/diesel. First you use photosynthesis to create sugar: CO2 + H2O + sunlight ==> O2 + (CH2O)n. Plants are basically made of really long sugar molecules (cellulose). You then ferment the sugar to create alcohol: (CH2O)n ==> C(n)H(2n+1)OH. At some point we'll probably figure out a way to go straight from the raw ingredients (CO2 + H2O + sunlight) to alcohol, at which point you're converting solar energy straight into liquid fuel.
Re: (Score:3)
That's why you build new houses around this reactor to channel sunlight into a centralized location in the basement!
Re: (Score:3)
Could be very useful in large scale industry -- the energy required to produce CNG or Aluminum is pretty high.
Attaching a "3000-degree solar zinc reactor" to an aluminum plant isn't going to be a big deal.
Re: (Score:3)
The question is whether it exceeds efficiency of other solar-to-electricity production.
It doesn't need to be better, or even as good. Being able to store the energy and generate baseload electricity is a huge advantage, and the inability of most solar power systems to do this is the main reason why they don't easily scale beyond a small fraction of total capacity.
Re: (Score:3)
Re: (Score:3)
Re:Darn that dirty hydrogen (Score:4, Interesting)
coal is very easy to move around, all you need is a bucket big enough.
Hydrogen is very hard to move around under pressure. as one of the other ./'ers aid like trying to hold water in a strainer.
Even Gasoline is relatively easy to transport.
Re:Darn that dirty hydrogen (Score:5, Interesting)
You're proposing a cycle that goes something like:
solar mirrors -> zinc reactor -> hydrogen furnace -> turbine
Why not just use the old and tried method of:
solar mirrors -> hot steam -> turbine
It would be simpler and far more efficient.
Now, the story is interesting because it's about creating hydrogen using sunlight, without converting the sunlight to electricity first.
Re: (Score:3)
compressor -> solar mirrors -> turbine
Re:Darn that dirty hydrogen (Score:4, Insightful)
Maybe to not have to deal with not being able to produce power at night? Yes, the fuel can only be generated during daylight hours, but the fuel can be consumed at any time.
Re:Darn that dirty hydrogen (Score:4, Informative)
Note that while it has the highest energy by mass, by volume it's actually pretty low, though it does beat LiIon. This also doesn't count the vessel needed to contain it - not a big deal for a massive cylinder at a factory, but it's a substantial mass/volume hit to include a 700 bar pressure vessel in a car.
Re:Darn that dirty hydrogen (Score:5, Insightful)
You are talking "energy density" as density relates to weight. Unless you're talking spacecraft, energy density related to volume is usually a lot more important. Look at your car's design. When the engineers designed your car, were they more worried about the WEIGHT of the gas in the tank, or the VOLUME of the gas tank? If the weight of the gas went up 50%, probably not all that big of a deal, make stronger tank straps and maybe reinforce the tank a little. But imagine the tank SIZE going up 50%. OK now we're seriously eating into your trunk space. Or look at that in reverse, if the manufacturer wants to double battery life in your MP3 player, he can make it twice as heavy or twice as BIG, which do you think he will want to do, which product will people buy, the heavier one or the big brick? Here down on earth, size matters. Weight is more important if you're going to orbit it.
Re:Darn that dirty hydrogen (Score:4, Informative)
The leaks may be dangerous, but a hydrogen leak simply escapes to atmosphere and dissipates. A gasoline leak collects on the ground and acts as both a poison if you touch it and worse if the stuff finds a source of ignition. It also pollutes ground water, streams, etc.
Dump out a gallon of gasoline and a gallon of hydrogen and see which one causes a bigger problem.
Re:Darn that dirty hydrogen (Score:5, Informative)
Hydrogen exceeding ~4.5% in air is explosive, so a slow leak in a ventilated area just escapes into the atmosphere. A faster leak, or a poorly ventilated area presents a tremendous explosion potential. Remember the reactor buildings in Fukushima? Those were from hydrogen building up inside the building.
Re: (Score:3)
Hindenburg wasn't an explosion, and it was much higher than 5% hydrogen. So, yea, I'm sticking with Fukushima.
not any more, read about formic acid (Score:5, Interesting)
it can be stored in vast quantities in the form of formic acid and then released and restored in a continual cycle. there is obviously efficiency losses but apparently its very practical as it allow storage of large amount of hydrogen at a very high density in a room temperature atmospheric pressure liquid,
that is basically as safe as vinegar.
I was thinking this clean hydrogen would be perfect in so many parts of the world where their is plenty of sunlight but the land is otherwise of low value.
ps: its the nail polish like odor that gets released when ants die, and more specifically when they get crushed. its probably something they are sensitive to, so hopefully our green cars in the future dont get covered with ants in because of the pheromone.
Re: (Score:3)
formic acid will fuck you up though... blind, and eventually dead.
Store it as fertilizer etc (Score:5, Interesting)
As a fuel hydrogen gas is a pain to store and transport in comparison to butane, propane etc or a liquid fuel, but if you can make it at sane costs where you need it then you don't need to store or transport much of it.
Re: (Score:3)
Hydrogen has many uses that do not rely on being able to store it. For example, the Sabatier reaction [wikipedia.org] combines hydrogen with carbon dioxide in the presence of a nickel catalyst to produce methane and oxygen. And methane is the primary component of natural gas, so I'm sure that you can see why that is useful.
Hydrogen can also be used together with carbon monoxide in the Fischer-Tropsch process [wikipedia.org] to create liquid hydrocarbons, which could be used as synthetic petroleum. In other words, another very advantageous
Comment removed (Score:5, Interesting)
Re:Darn that dirty hydrogen (Score:5, Insightful)
When we (the US) get rid of the penny there will be a HUGE supply of zinc out there.
Re: (Score:2)
Agreed. Any denomination less than 5c is just dead weight now. I would say 10c should be the smallest were it not for the ubiquitous quarter.
Re: (Score:2)
How about we just adjust the currency. Let's shift it one decimal point and everything that costs a dollar is now 10 cents and if you make 3000 dollars a month it's now 300 dollars. New currency can be issued and all the old money face value is now down one decimal place. Then a coke will be 6 cents at work instead of 60 and the penny is relevant again. No more trying to feed worn bills into the vending machine.
Re:Darn that dirty hydrogen (Score:5, Informative)
Re: (Score:2)
So help me out here, photolyzed zink oxide is pure zink vapor, and the oxygen goes someplace, (out the stack?) and then the zink gloms onto oxygen from the water. So, wouldn't that tend to yield fairly pure zink oxide after it cools?
Self-sustainable... pfft. (Score:5, Insightful)
It's not self-sustainable. It's sustained by the sun.
Re:Darn that dirty hydrogen (Score:5, Interesting)
Clean in this context probably refers to not requiring fossil fuels.
Apparently the Zink Oxide is recoverable as well:
As well as a lack of emissions, the other good news is that the zinc oxide can apparently be reused, meaning the solar reactor is theoretically self sustaining as it only relies on materials and energy that are renewable.
although it isn't spelled out how that is performed, or if any processing is required, and if so, at what cost.
To heck with scaling this up. Lets scale it down so I can have one in my back yard, or at every corner gas station. A small reactors working any time there is sunlight and water scaled just large enough to keep your car topped off makes a lot more sense than trucking hydrogen around. Especially if the zink oxide recovery can be built in.
Then maybe hydrogen cars can become a realistic option rather than the proof of concept models and conversion kits for fleet vehicles.
Re:Darn that dirty hydrogen (Score:5, Insightful)
It operates at ~1700C. You're not going to get sustained temps like that without large mirrors and large reactor vessels. So it's not going to scale down terribly well.
Re:Darn that dirty hydrogen (Score:5, Insightful)
Well, scaled really small, it just works slower to fill your H2 tanks.
Photo-voltaic panels ---> Electricity--> heat small continuous flow reactor chamber (maybe no bigger than your thumb). Maybe the whole package sits beside your house in a package the size of an air conditioning compressor, while the panels are on the roof. We got a boat load of roofs in this country.
Re:Darn that dirty hydrogen (Score:4, Interesting)
You can melt steel with a 10' mirror. You can't melt *much* steel, but getting high temperatures isn't a problem; the question is whether the yield is enough per square meter of mirror to be worth it, and whether it scales up to higher efficiencies as you increase the area of the mirror and the size of the reactor vessel.
Re: (Score:2)
Re:Darn that dirty hydrogen (Score:5, Informative)
Electrolysis tends to eat away at the materials causing you to have to get more. This is fairly closed loop in that the only ingredient is water and heat. Instead of mining zinc for the rectors that will run indefinitely (supposedly) you would have to continuously mine the metals used for electrodes in electrolysis. Cleaning and replacing these parts can be "dirty" where this reactor seems to eliminate that component. The only thing I think you'd have to do with this is grind the zinc back into powder. (as I assume it probably melts and coagulates?)
Re: (Score:3)
Zink Oxide is recovered. Its not consumed.
Re: (Score:3)
Nopee. Zinc is recovered. you need to do another chemical process to make zinc oxide. gee, i wonder how green that process is, which gives us green hydrogen?
Go read TFA, or go directly to the University of Delaware's page from which the TFA was sourced:
http://www.udel.edu/udaily/2012/apr/solar-reactor-040312.html [udel.edu]
It CLEARLY states:
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.
Zink oxide in, heated to drive off its oxygen, exposed to water where it scavenges oxygen, which frees hydrogen, and you get zink oxide back. Probably nearly pure.
Re:Sustainable? Not really. (Score:4, Informative)
Zinc! COME BACK ZINC! (Score:4, Funny)
Great, just one more think to go wrong when pimply faced teenagers wish to live in a world without zinc.
How down-scalable is it? (Score:5, Interesting)
Re:How down-scalable is it? (Score:5, Interesting)
It seems to me that as an energy storage medium (and that's what it is, it's not a fuel "source") Hydrogen would lose out to a plain old chemical battery when all it needs to do is sit in your basement. One of the primary pitfalls of a battery is weight and size, but that won't much matter if you just dig a deeper hole in the ground and never move it.
Anyways, going Solar -> Hydrogen -> Electrical sounds a lot more complected (not to mention inefficient) than just Solar -> Electrical.
Re: (Score:2)
Google "battery"
Re: (Score:2)
Re: (Score:2)
Looks interesting... (Score:5, Funny)
But it's pointless to speculate about its utility without knowing how much hydrogen a given unit can produce, how much that unit costs, and how much maintenance it will need.
And the four giant robot arms the operator wears don't fill me with confidence.
Global Warming! (Score:5, Funny)
But if you burn hydrogen, it creates dihydrogen monoxide, a known greenhouse gas!
This is terrible!
Re:Global Warming! (Score:4, Insightful)
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.
But is it really emissions-free? (Score:5, Interesting)
Re: (Score:2)
plenty of zinc in the world....aren't US pennies made of the stuff?
Anyway, from TFA:
As well as a lack of emissions, the other good news is that the zinc oxide can apparently be reused, meaning the solar reactor is theoretically self sustaining as it only relies on materials and energy that are renewable.
Re:But is it really emissions-free? (Score:5, Informative)
You burn zinc metal. Really. The zinc oxide and tower are not the interesting part. That is simply an alternative method of smelting a source of zinc to obtain zinc metal.
The deeper linked articles say "the hoppers will feed zinc oxide powder (a benign substance resembling baking soda) onto the ceramic layer, causing a reaction that decomposes the powder into pure zinc vapor. In a subsequent step, the zinc will be reacted with water to produce solar hydrogen."
Ok.
Zn(s) + 2H+ -> Zn2+(aq) + H2(g)
but
Zn2+ + 2OH- -> Zn(OH)2(s)
So the water that's left over will contain a zinc hydroxide particulate (or sludge).
The zinc hydroxide is an emission. Might be better than a gaseous emission, but it's still a waste product. If this system is truely closed with respect to zinc, then the zinc hydroxide has to be converted into zinc oxide or somehow directly smelted back into zinc vapor. That's the missing element from the article in my opinion.
Other questions: how fast is the aquoeous reaction (toss zinc in a glass of water -- it's slow at standard temperature and pressure); what is the equilibrium pressue of H2 above the liquid (if it's a low partial pressure, then you need to both maintain a vacuum over the liquid and compress the drawn-off gas); what is the net energy output of H2 versus the input of heat (assuming that you close the system with respect to zinc by drying and converting the sludge back to zinc metal).
Re:But is it really emissions-free? (Score:5, Informative)
Just to be clear, chemically this is not hard:
Zn(OH)2 -> ZnO + H2O at about 800 C (this is a calcination reaction)
It's a materials handling issue. Dewatering a sludge, drying a dewatered sludge, and, if necessary, calcining the zinc hydroxide separately from forming the zinc metal, all involve some technically complicated additional steps.
Re: (Score:2)
The zinc oxide is just used in an intermediate step. It is not permanently depleted in the overall reaction. You start with zinc oxide and water. You end with zinc oxide, oxygen, and hydrogen.
You take zinc oxide, use sunlight to produce zinc vapor and oxygen. Somehow the zinc vapor and oxygen are separated so that they don't form zinc oxide again (the oxygen is no longer needed in the device and is discarded as far as the generator is concerned. The zinc is then reacted with water to produce zinc oxide and
Re:But is it really emissions-free? (Score:5, Informative)
Nope. Zn(OH)2. You have to do something else to convert the hydroxide into an oxide.
I agree that you can't simply condense the Zn vapor into a liquid or solid. In normal thermal smelting the metal is chemically reduced to draw off the oxygen using a reducing agent such as carbon monoxide. At very high temperatures, you can force a metal oxide to form a plasma of dissociated ions, but as you indicated something has to draw off or separate the oxygen, and something also has to donate electrons to the zinc ion plasma. Might be a set of high temperature electrodes?
What happens to the oxygen? (Score:2)
Re: (Score:2)
Seems to be the thermal decomposition on ZnO
Zinc Oxide --> Zinc + Oxygen
Followed by the reduction of water:
Zinc + Water --> Zinc Oxide + Hydrogen
If the Zinc Oxide is reusable that's pretty decent, but I wonder how it compares energy wise to other methods of water separation.
is this useful? (Score:2)
Is it any easier to transport hydrogen from where the sun shines to where it's needed as fuel as compared to electricity? It seems that the energy needed for compression and leakage from storage tanks, fittings, and transmission lines would result in significant energy losses. Plus a 200 mile hydrogen pipeline from the sunny desert to a populated area seems prohibitively more expensive than a power line.
Is this hydrogen plant really any better than just creating electricity? Granted, electricity can be hard
And what about that ZnO? (Score:2, Insightful)
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?
Re:And what about that ZnO? (Score:5, Funny)
Re:And what about that ZnO? (Score:5, Funny)
You mean if we get rid of them like the Canadians plan to do? Won't that inflate the price of our thoughts by 500%? Egads! Intellectual property will be too expensive for everyone.
production does not equal efficient production (Score:5, Insightful)
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.
This is a threat to public safety (Score:4, Funny)
We here at the Clean Alternative Fuels Committee see this as just too dangerous to allow and plead to the US Government to outlaw this potentially dangerous technology. We simply can not trust the public with the ability to produce Hydrogen which could lead to the creation of Mini-H bombs. We propose the advancement of existing Hybrid technology as the clean energy alternative for a successful future and is wholeheartedly endorsed by our Charter Members: Chevron, Exxon-Mobile and Shell.
Byproduct of hydrogen combustion (Score:2, Troll)
What is the chemical result when hydrogen is burned? Water vapor.
What is the atmospheric component that is the predominant contributor to the greenhouse effect? Water vapor.
So lemme get this straight: all these disciples of the so-called hydrogen economy want us to burn hydrogen in energy-equivalent amounts as the fossil fuels we use now, thus putting more of the worst greenhouse gas of all directly into the atmosphere? Sure, some of it will change phase and precipitate back into oceans and lakes and riv
Re: (Score:2)
How can it not return to the water cycle? If you have too much water vapor in a given section of atmosphere, it precipitates. Isn't that what clouds and rain are? Where does the water for this hydrogen come from? Space? Did everyone forget high school science class in this thread?
But I looked it up to be sure: http://en.wikipedia.org/wiki/Greenhouse_gas#Role_of_water_vapor [wikipedia.org]
Re:Byproduct of hydrogen combustion (Score:5, Insightful)
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.
Re:Byproduct of hydrogen combustion (Score:5, Insightful)
Re: (Score:3)
Which - duh! - happens to be exactly the direction we're already inexorably headed. So to recap: add more water vapor to an already heating atmosphere, thus retaining more of it in the atmosphere, and thus further increasing atmospheric heating. Rinse, later, repeat. Did I get that right?
Re: (Score:3)
Ummm... no, I didn't get that right: "later" <--- "lather"
Re:Byproduct of hydrogen combustion (Score:4, Insightful)
Re: (Score:2, Informative)
That's what I was thinking.. What's the carbon output of obtaining, refinement and purification of the Zinc Oxide?
Re:so... (Score:5, Informative)
TFAs: Read one today!
Re: (Score:2)
Didn't actually answer his question - you've got to produce the ZiO2 once, and the recovery is never going to be 100%, so there'll be a need for steady (hopefully low-level) replacement.
So, anyone know how dirty zinc mining and refinement are?
Re:so... (Score:5, Informative)
The recovery could be pretty close to 100%; the reactor's only products are oxygen and hydrogen, both of which are gases, so capturing zinc should be simple enough.
Zinc is usually found in conjunction with other metals like copper, so we get most of it "for free". Zinc oxide is actually a lot easier to produce than pure zinc, so refinement costs should be relatively low. The most common ore of Zinc, Sphalerite, is ZnS, and converting it to ZnO just involves adding oxygen and heat:
ZnS + (3)O2 = ZnO + SO2
The sulphur dioxide can be converted to sulphuric acid (H2SO4).
No carbon involved.
Besides, we already use >10 million tons of the stuff per year, and have at least a couple centuries more deposits to mine (to say nothing of recycling), so using a bit for this solar plant wouldn't even be noticed.
Re:so... (Score:4, Insightful)
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 [wikipedia.org]
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.
Re: (Score:2)
10000 mirrors (Score:3)
There are already solar towers using massive arrays of mirrors all aimed at the same point. This could presumably use something similar.
Re:40 rods to the hogshead (Score:4, Insightful)
2. Neither of the links in the submission go to a scientific article. One goes to a press release on the UD website, and the other goes to a blog that summarizes the press release.
3. Complaining about customary units does not make you cool or indicate scientific literacy. However, it does make you sound like pedantic, whiny bitch.
You may now go back to looking at cat pictures and masturbating.
Re:40 rods to the hogshead (Score:5, Insightful)
1) While it's in use by a lot of people, _most_ people don't use it.
2) It's about a scientific article, so we're talking about science. It just makes sense to use celsius or kelvin in a science topic. If we're talking about the distance between planets, we use AU or light years. If we're talking temperature, fahrenheit is not the first choice.
Re: (Score:3)
To be honest, Fahrenheit is probably the single worst "traditional" unit. All others you can kinda sorta get used to, because the conversions are linear and fairly straightforward - for the most part, you can assume 2 pounds in kg, 3 feet in meter, and 1.5 km for a mile, and not be too much off.
But Fahrenheit conversion is just crazy - not only the factor is a very inconvenient 9/5, but you have to add/subtract 32, and not forget when you do it before multiplying, and when you do it after. Yes, yes, if you
Re:40 rods to the hogshead (Score:4, Interesting)
Re: (Score:3)
Yeah, because the Rest Of The World ( aka Not North America ) uses Kelvin instead of Celsius.
Sigh...
There are far more 'laypeople' in the world who use Celsius than there are those who use Fahrenheit.
Re: (Score:2)
My question too. I've been off-grid on PV solar since 1980 or so, even charge my Volt with it. 3k degrees won't be reached easily or often with the tech I know, even with trackers and concentrators. So not only "how much energy does it make vs the same sq feet of PV panels" is in question, but how much per average day per sq foot when it's partly cloudy and so forth. Gheesh and then, electricity is hard eno