Posted on 05/17/2007 4:09:52 AM PDT by saganite
ping
The savings will be there when gasoline hits $15 a gallon. Once the population of China and India own cars at the same rate that Americans do we will see the price of gas shoot up to astronomical figures.
Its simple supply and demand.
Agreed. Hopefully by the time that happens this technology (or something similar) will be advanced enough to be economically feasible.
“A midsize car with a full tank of aluminum-gallium pellets, which amounts to about 350 pounds of aluminum.”
I wonder how much water, which would need to be stored in a separate tank until needed, is required to use up all that aluminum? I guess I should really ask that the other way around, since it is the water that is the source of the hydrogen fuel. Seems heavy compared to the 80 lbs of gasoline or so I carry in my car’s tank, but maybe the fuel cell would be sufficiently lighter than an internal combustion engine to make up the difference.
Interesting concept, but I don't see me shoveling 350 lbs of aluminum pellets into my car to drive it for a week. Process needs to get far far more efficient to be useful.
I’m also wondering about the efficiency of this cycle. The article states that considerable heat is also liberated in this reaction - how much, and is it of any use? I guess it might be useful for heating the car in the winter. How efficient is the process of reforming the aluminum oxide back to aluminum? The devil’s in the details with these schemes. Of course, it’s not hard to beat the 25% (or so) efficiency of the gasoline powered internal combustion engine.
Yes, smelting aluminum is extremely energy intensive. That’s why many of the major aluminum producers have been in places like Quebec or British Columbia, located nearby to major hydroelectric facilities. That’s despite the fact that the bauxite comes from the other side of the world.
The other problem is how do you dispose of the solid "ash" Al2O3 Without looking up the bond energies and doing the calculation I'm guessing with you that there is a lot of waste heat in this operation. My idea is to run a car on water and calcium carbide Then you have to dump the Ca(OH)2
From your comments I gather you don’t believe recycling the aluminum as mentioned in the article is feasible?
Obviously not. Once it's burned, then it becomes aluminum oxide that has to be re-reduced electrically to metallic aluminum; that -1600 kJ/mol again.
Seems like the extra cost of transporting 350 pounds of aluminum pellets (plus some amount of gallium) from the nuclear reactor would be significantly higher than current transportation costs for an equivalent amount of gasoline (say 20 gallons at about 120 pounds). Plus the used Al has to be transported back. Six times the transport costs of gasoline...
Plus, we would be transporting a whole lot of water. Interestingly, the process requires approx. equal masses of Al and water. So the 350 pounds of Al requires transporting an additional 350 pounds of water (42 gallons).
Finally, if the water is emitted as steam won’t the global warming freaks be offended? Isn’t water vapor a potent greenhouse gas? Or maybe we can extract the heat energy and emit the water as liquid. Crowded highways will be permanently wet as each car on the road dumps a gallon of water on each 8 miles of highway (this may not sound like much, but consider a heavy traffic day with 75 cars per minute - this would be the equivalent of 1/3 inch of rain per day on the highways).
That said, if the process could be made more efficient (smaller Al-Ga granules to increase surface area) and possible recycling of exhausted water to reuse in the process) there may be a point where it becomes at least somewhat useful...
Of course, but it's not a bad start for a new idea. Give it a few years and see where it lands.
I don't see me shoveling 350 lbs of aluminum pellets into my car to drive it for a week.
I don't either. It's probably be more like a large bin elevated above your head, you pull a lever and the pellets slide down into the holding container. The water can be pumped in like gas is now, or simply dropped with the pellets. (from a separate bin... don't want them reacting before they get put in the cars!)
How would the by-product alimuna be removed? My guess: you flip a lever on the car's container (before re-filling) and it all drops out into a pit in the ground, like a Jiffy Lube basement. let gravity do all of the work.
Anything to make the Middle East (and Islam) irrelevant again!
The energy path is now {oil,coal,hydroelectric,nuclear->electricity)->aluminum->water hydrolysis->hydrogen. There is a energy conversion loss at every step. This proposal is just making the aluminum alloy into the store of energy. Aside from a safer way store energy than gaseous hydrogen, I see little merit in this invention. The "waste" product will need to be recycled as you are no longer just generating CO2 and H20 as you drive.
read this aluminum smelting
Finally, if the water is emitted as steam won’t the global warming freaks be offended? Isn’t water vapor a potent greenhouse gas?
That’s always been my first question regarding the use of hydrogen in vehicles. The increased production of the greatest greenhouse gas there is never seems to be addressed in any of the hydrogen schemes. If there is concern about a minor greenhouse gas like CO2 then you would think the greens would be falling all over themselves to prevent the use of hydrogen.
All of this is fine and dandy, provided you have plenty of electrical capacity. I submit, that we need a HUGE investment in Nuclear Powerplants. Once we have enough spare electricity, we can create whatever fuels we need, and make everyone pretty happy.. I am dismayed that the GW fanatics don’t jump on this bandwagon.
I read the article and wondered about this quote:
“Recycled aluminium requires only 5 per cent of the energy required to make “new” aluminium. Blending recycled metal with new metal allows considerable energy savings, as well as the efficient use of process heat. There is no difference between primary and recycled aluminium in terms of quality or properties”.
Does this not apply as regards the recycling mentioned in this article?
That's not a fair comparison. It leaves out all the conversion losses incurred in generating the hydrogen. A fair comparison would start at the primary source of energy and include all the conversion losses on the way to the wheel. Gaseous hydrogen is hard to store. You can lose half a tank in a week without driving anywhere. That is also a loss in the total chain from primary energy to the wheels.
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