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Posted on 08/11/2011 11:40:12 AM PDT by Freeport
While roofs across the world sport photovoltaic solar panels to convert sunlight into electricity, a Duke University engineer believes a novel hybrid system can wring even more useful energy out of the sun's rays.
Instead of systems based on standard solar panels, Duke engineer Nico Hotz proposes a hybrid option in which sunlight heats a combination of water and methanol in a maze of glass tubes on a rooftop. After two catalytic reactions, the system produces hydrogen much more efficiently than current technology without significant impurities. The resulting hydrogen can be stored and used on demand in fuel cells.
For his analysis, Hotz compared the hybrid system to three different technologies in terms of their exergetic performance. Exergy is a way of describing how much of a given quantity of energy can theoretically be converted to useful work.
"The hybrid system achieved exergetic efficiencies of 28.5 percent in the summer and 18.5 percent in the winter, compared to 5 to 15 percent for the conventional systems in the summer, and 2.5 to 5 percent in the winter," said Hotz, assistant professor of mechanical engineering and materials science at Duke's Pratt School of Engineering.
(Excerpt) Read more at sciencedaily.com ...
This gets dredged up on every thread about hydrogen. At low temperatures (around room temp), there "is" no "hydrogen embrittlement problem". The reactions that cause it go so slowly that it would take centuries to weaken iron. And yes, I can quote chapter and verse, and have done so on other threads.
are you for it? or agin’ it?
If this device can produce energy cheaper than some other methods; then it will carve out a niche in the market.
If massive government subsidies are required — then that too is all you need to know about the economic viability of the technology.
BTW, storage would not have to be a big problem. First off, you would only need to store a couple of days worth of hydrogen. That's a lot easier to manage than storing fuel for a month or more (as in the propane tanks). Also, hydrogen storage isn't limited to pressure tanks. There are a great many alternatives, including metal hyrdides.
Actually, there is an engineer in (I think it was) New Jersey who built his own home "hydrogen energy system". For storage, he used old propane tanks. He just used bigger tanks and stored under lower pressure. His "one off" system was quite expensive, but most of that was "in the engineering". He was developing a business to sell such systems to "rich guys who own islands" and who wanted all the amenities of civilization, but cheaper than boating in diesel. His estimated cost per system wasn't all "that" unreasonable for "boonies" operations. I'll see if I can find that article again....it's been a few years since I read it.
If the hydrogen is derived from methanol why not just use methanol? If methanol is derived from natural gas or coal or wood why not just use natural gas or coal or wood?
I’m one of those who think Natural Gas was here from the beginning of the planet..................
It was on the order of $500k - he used solar to crack hydrogen, then used the hydrogen to make electricity.
It worked - he powered his house.
Some probably was. Methane is the most stable form (without the presences of oxygen) for Carbon and Hydrogen to exist. But decaying matter clearly produces methane. Swamps, dumps, etc, all produce methane. When algae, plankton, etc, gets trapped in sediment on the bottoms of oceans and lakes, then gets covered up under layer and layer, having methane down there should be expected.
Storing propane and hydrogen are two very different things. Propane is easy to maintain as a liquid at relatively high pressures, not so hydrogen. If fact hydrogen is very difficult to hold as a gas because of its low molecular weight.
Hydrogen has the added danger of producing an invisible flame, not so propane.
Storing propane as a low-pressure gas is no more difficult than propane (and, in fact, old propane tanks work just fine with hydrogen). Yes, hydrogen's flame is invisible..a disadvantage. But, hydrogen is very much lighter than air, so tends to disperse much more rapidly than propane (or gasoline fumes). But the technology exists for safe use of either. There is nothing "exotic" about hydrogen storage. Millions of pounds of hydrogen are stored and used in myriad different size scales on a daily basis, from lecture bottle size tanks up to tank-truck size tank assemblies, in hundreds (if not thousands) of locations around the US.
Yeah, that's about the cost I recalled (and have found online). What I haven't found was his estimate for what one of his "commercialized" systems would run, which was "much" less. I seem to recall that it ran around $50K, but I certainly wouldn't swear to it.
The article is on FR ... somewhere. I was interested when it was first posted, because my cabin is “off the grid.” Landlocked - adjacent owner will no allow a utility easement - so it is off the grid permenently.
But his system is too expensive, too complex, and too hard to maintain - a jerry can of gas for the generator is dirt cheap, in comparison.
Also to be found on FR - honda or toyota, I forget which, had an experimental sunlight - to - hydrogen station for refueling fuel cell cars.
Put thos three together, and $50k is probably a high estimate.
I think you could do it now, for $20k in panals, $10k for the cracker, $10k for the fuel cells, and use the rest for plumbing...
“The roof, the roof, the roof is on fire ....” ;)
The dramatic flames you see, are from burning the rocket fuel they coated the skin with. As other posters have pointed out, hydrogen flame is invisible.
Thanks for the laugh....it’s been that kind of week...
I didn’t suggest “exotic” just more difficult which translates into more expensive if any quantity is going to be stored.
Yes, at LOW pressure, hence low volume, amounts, no problem but when you talk about the many facilities storing the gas you don’t mention the pressures involved nor the cost of compressing and storing at high pressures.
And at higher pressures hydrogen is virtually impossible to seal in as it will penetrate many metals.
Storing at home is not something I would want to do so perhaps immediate consumption by a fuel cell might be feasible but still storing gaseous hydrogen and liquid propane are very animals particularly if we’re talking about doing so at home.
Nope. Not true. For "non-transport" use, low pressure is just fine...you just need to use bigger tanks, which are readily available, and relatively cheap. The only time ultra-high pressures are needed is when you try to use hydrogen as a transport fuel, where energy density is hugely important.
"Yes, at LOW pressure, hence low volume, amounts, no problem but when you talk about the many facilities storing the gas you don’t mention the pressures involved nor the cost of compressing and storing at high pressures. And at higher pressures hydrogen is virtually impossible to seal in as it will penetrate many metals."
Ah, yes. The standard "mantra" about the insurmountable difficulties of hydrogen storage. Yet hydrogen is in use, in hundreds and thousands of locations at low, intermediate, and high pressures, without problem, on a daily basis. And no exotic or unusual technology is needed. Yes, you "do" have to be careful in choosing the materials to use, but all the engineering to do that is "off-the-shelf". I've worked with hydrogen for years. I don't notice that properly-installed hydrogen systems are any more prone to leak that any other compressed gas system.
"Storing at home is not something I would want to do so perhaps immediate consumption by a fuel cell might be feasible but still storing gaseous hydrogen and liquid propane are very animals particularly if we’re talking about doing so at home."
People store and use gasoline and propane "at home" all the time. Hydrogen will be no different when its turn rolls around.
Hmmm....I missed that one. Hadn't heard word one about it. If you run across a link, shoot me a Freepmail. In the meanwhile, I'll give Google a go and see what turns up.
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