Posted on 05/17/2007 4:09:52 AM PDT by saganite
fat chance you’ll be driving a car with that anytime soon.
Nope, recycling aluminum is just melting it (to a first approximation), but reclaiming this alumina back into aluminum metal is equivalent, minus mining expenses and separating the alumina from the ore, getting the aluminum from the alumina in the bauxite ore in the first place.
I think I said that
That answer is pretty easy. The cost of the aluminum
The answer isn't easy at all. The current cost of aluminum is based on the current demand for aluminum. Refining aluminum from aluminum oxide requires a LOT of electricity and currently there is not much excess capacity in the US electric supply, so if you start using aluminum as an energy carrier, then the demand for aluminum (actually the electricity to make it as well as the facilities to refine it) will vastly increase, shoving the transportation energy demand back on the electric grid which just doesn't have the capacity. I read somewhere that replacing the transportation energy demand with electricity would need about 200 new nuclear generating stations. That is why that even if this is technically feasible (and how do you get rid of the solid waste produced? Big recycling costs associated with the recapture of the al2o3), it isn't economically feasible on anything but a demonstration scale without the electric generating capacity to back it up.
“Above the clouds, the sun is always shining...” is a lyric from an old gospel song.......
Air conditioners and refrigeration systems can run on ammonia like they did before DuPont invented Freon. That requires heat to boil the ammonia to make it a gas. The waste heat from the chemical reaction could be used for that, as could the exhaust.......
People keep saying we don’t have the electrical generating capacity, but the DOE numbers disagree. Look at the numbers in the link in post 108.
We may not have excess capacity on summer days during peak demand, but the overall excess capacity is 20% — in 2004 that was 150,000MW excess capacity.
If used to charge electric vehicles, that would be enough for 100 million cars to drive 100 miles every day. This aluminum oxidation process feeding hydrogen to an internal combustion vehicle is much less efficient than an electric car would be, but it still works out to 36 miles every day for those 100 million vehicles. Those would be expensive miles — equivalent to $5 gasoline — but there are many options to producing electricity compared to finding more petroleum.
You are correct that supply and demand will drive up the price of electricity and therefor aluminum if this were to be widely adopted. If it were widely adopted, however, and demand fell for gasoline then oil prices would fall. It would be impossible to switch everything overnight, so the volatility in price would be minor and spread out over decades. All the while, that additional generating capacity you talk about will be coming on line, right ?
As far as the “waste” goes, in the vehicle, the fesh aluminum moves from its tank, to the reaction chamber, to the alumina tank. Filling stations pump out the alumina at the same time they pump in new aluminum. Tanker trucks pick up the alumina when they deliver new aluminum, compared to leaving empty after delivering gasoline. More expensive than dead-heading back to the depot, but not all that much more.
The other peculiar thing about aluminum is that you can’t shut the refineries off. If they cool down for more than 4 hours the aluminum solidifies necessitating a complete rebuild of the tank. and about power, we may have enough peaking capacity (read expensive electricity), but is the base load capacity there? The cost of electricity varies form moment to moment as the generation mix changes during the day. Electricity must be generated in exactly the amount used; there really isn’t any storage any significant increase in al production is going to drive the cost of electricity up and decrease the reserves.
Actually, I think the excess capacity is all at night and the baseload capacity is more than the night-time demand.
So as long as you do your aluminum recycling at night, you are ok ;-) The author does make the point that new generating capacity dedicated to aluminum recycling would be best. I’m just saying we have some excess capacity that could be used without waiting for that.
Controlling the reaction to provide the amount of hydrogen needed according to varying demands of the vehicle seems like it is left out of the article entirely.
It wouldn’t make sense for the reactor to be a single big tank where all the aluminum and water is dumped at once. Similar systems that I’ve seen move the reactants together via screw delivery systems into the reaction chamber. So you can move only as much as necessary to provide the hydrogen output needed at that time, and few of the aluminum pellets would be wasted when the reaction (and vehicle) are shut down. Just those remaining in the reaction chamber and flushed out with water into the alumina waste tank. Maybe not even those, if the reaction is allowed to continue and the hydrogen from those last pellets is compressed for storage in a relatively small gaseous hydrogen tank. I think a vehicle reactor would need to do that anyway, so it could produce hydrogen at an average rate and temporarily store it to meet the varying demands of the vehicle.
I would be much more expensive transporting aluminum over the road than electricity over the wire.
If you have aluminum, you have 1/2 of an aluminum air battery. You do not need a fuel cell. Look up mechanically recharged aluminum batteries. They have been around for 40 years.
If someone ever figures out how to keep an electrically rechargable aluminum battery from gelling up, we would not even need gasoline. It would provide about 10 times the capacity of the best lithium battery.
I only have high school chemistry but know you don’t get to split water, make hydrogen, for free. It takes energy and in this case it’s supplied by aluminum which is quite expensive. In supplying this splitting energy the aluminum becomes aluminum oxide. To reuse the aluminum oxide you turn it back into aluminum by electricity.
I fail to see what’s so clever about this scheme
thanks, bfl
Nothing that I can see either other than it may be more energy dense than batteries. For that matter you could run a car on calcium carbide and water, but no one does it. might be a good test bed for this process
Instead of using electricity to make hydrogen by splitting water, this process uses aluminum which itself is made by using electricity, to make the hydrogen. So same or more probably more electricity is used to make the hydrogen.
Look up powerchips.gi
You got to be a little careful with that number. A lot of those MW are in very old plants, many of them small (less than 1 MW industrial units) that are rarely utilized because of their high costs, fuel type (lots of diesel or or distillate) and poor emission profiles. They contribute little but remain "on the books" as part of the installed base.
The real issue with generating capacity today is the need for new baseload power plants --- those in the 700 and 1200 MW range, that can generate power around the clock for 2-3 cents/kWh. (That's new coal and nuclear units.) Our baseload demand keeps growing as population and economic activity grows and that's the segment of the fleet we need to focus on now. The 90s saw large growth in gas turbines for both simple and combined cycle plants, but with high natural gas prices now, we don't want to rely on those for baseload power. They work very well for cycling and peak power operations, but they are too expensive for baseload operation.
Or thermite.
I think is magnesium oxide and aluminum powder.
Do you have any idea how expensive solar power really is? If it made financial sense, you wouldn’t need the government pushing it.
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