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 ...
1) What is done with the O2/CO2 gerenated by the catalyst?
2) How is the hydrogen hydrogen embrittlement issue resolved?
3) Since the cycle is not self starting, the system needs the reserculation & compressor running, where does the startup energy come from?
4) While a minimal economic study was done compairing the proposed system to current systems, how much energy is required to build all the equipment: What is the infrastructure energy consumption vs. a conventionally electrified house?
5) What are the economics of the catalyst? Is it common or rare? Is it energy intensive to create, etc.
These backend questions, "hidden" cost items, trouble me the most about these "green" solutions. They turn out not to be very green at all.
PLUS where does the methanol come from?
I hear this is more difficult than it sounds.
methanol = wood alcohol so you have to cut down trees...............
of course you can also make methanol from COAL............................if this gets nny more stupider we need to shut down the Universities....................
You beat me to it. LOL
A gas line in your basement! What could possibly go wrong! Come on...
Hit NG with a spark and see what that’s like!
Let’s see, there are buses running around on the streets with compressed NG systems in them... I see they make the news every night because they’re blowing up all over the place.... /s
Would there have to be proper containment system for the hydrogen? YES! Is it a hugungus undertaking... No! It’s no more of an issue than an above ground liquid propane tank.
The horror! Those things explode all the time right? /s
The ISSUE is hydrogen embrittalment. THAT shortens the usable life of the system.
The mainteneance on the fuel cell: THAT shortens it!
Take your Hindenburg and stow it!
I was going to say “It’s not like methanol grows on trees.” (I know where it comes from btw)
Buy yourself a sense of humor.
Methanol is most commonly made from natural gas.
http://www.afdc.energy.gov/afdc/fuels/methanol_basics.html
Here’s a $ buy yourself a brain...
Even more evil..................
Absolutely wrong. Propane is liquid under reasonable pressure at room temperature. Liquid hydrogen turn to gas at -423F. Extreme cryogenics. PLUS liquid H2 takes up a lot of space to quote
The density of liquid hydrogen is only 70.99 g/L (at 20 K), a relative density of just 0.07. Although the specific energy is around twice that of other fuels, this gives it a remarkably low volumetric energy density, many fold lower.SO NO there really isn't a great deal of similarity between propane and liquid hydrogen.
You’re a total jerk aren’t you? LMAO
I've worked the design of propane and hydrogen storage and pumping/compression systems.
It is a heck of a lot more complicated and expensive than storing propane. Compressing it to a usable volume, the ease hydrogen leaks from systems due to the small molecule size are examples. Also the Group B rating for the Hazardous Area Classification makes equipment more expensive to manufacture.
Didn’t they have rooftop hydrogen at Fukushima Daiichi?
save
Not only that. Making methanol is made by the same process we make today, steam reforming natural gas.
So we steam reform natural gas to make methanol, to send through this process to make hydrogen.
Or we could just steam reform natural gas to make hydrogen in the first place.
However, as a fuel, hydrogen is really only useful in systems that are mass dependent like a rocket. It is really a lousy fuel.
Just use the natural gas in the first place.
The cycle rate on the renewing tends to be a little on the long-term side....
;-)
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