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An RC Car That Runs On Soda Can Rings
polyp2000 writes with an Engadget excerpt to inspire instant toy envy: "A pair of Spanish engineers have recently unveiled the dAlH2Orean (see what they did there?), a R/C car that runs on aluminum. Dropping a few soda can tabs into a tank of sodium hydroxide produces enough hydrogen to power the little speedster for 40 minutes — at almost 20mph."
Just on an intuitive level, I'm a touch surprised that they managed to get that much running time out of the system.
On consideration, of course, the energy required to coax aluminum out of whatever compound it has formed this time and into a bulk metallic state is pretty heroic. That does suggest that(while the aluminum oxide layer passivates it nicely under normal circumstances) bulk aluminum has some serious potential energy.
FTA: There may be another way to transport electricity, using the Aluminum battery as a medium. Each kilogram of Aluminum produced represents about 14 KWh of electricity, used to produce the ingots. This means that if we ship 20,000 Tons of Aluminum to Europe, we would be transporting the equivalent of 20,000,000 * 14 KWh of electricity. This is 280 GWh of electricity, enough to power 500,000 households in Europe for a year. The question, of course, is how can we free this electricity from the Aluminum transported. Here comes the Aluminum battery. Using Aluminum electrodes in a simple electrochemical cell, filled with seawater or Sodium Hydroxide solution and using a Nickel-Manganese counter electrode, the Aluminum will be oxidized to Aluminum Hydroxide and give off 3 electrons per Al atom used up in the reaction. A large part of the electricity stored in the above 20,000 tons of Aluminum can in this way be released, generating about 280 GWh of electricity and about 60,000 tons of Al(OH)3 sludge. This sludge could be recycled back to Iceland to generate again 20,000 tons of Aluminum to start the process of electricity generation anew. http://www.zpenergy.com/modules.php?name=News&file=article&sid=717
This happens much, much too often on Slashdot.
Aluminum takes a terrible lot of energy to refine from ore. The one good thing about that is that it's really easily recycled, so those aluminum cans sometimes get to be part of something again. But when you dissolve it in draino, and then, inevitably, dispose of the result in your landfill or sewer, you lose all of that energy and make some nasty pollution. What you get back in energy isn't a tiny fraction of what went in.
But they got a patent. Because the patent office doesn't care if your work is good, only that it's original. So, a lot of ignorant people will be impressed by their "innovation".
This would have been cool for a high-school science-fair project. Much too much bad science runs here.
Bruce Perens.
For those who don't recognize it, sodium hydroxide is more commonly known as lye. Not sure I would want to be in an accident in a full size vehicle powered by lye.
'The tyrant will always find pretext for his tyranny.' - Aesop's Fables
Hehe, this gives me the opportunity to pass along an old favorite to a much younger generation. We were doing this around the time that today's college students were being born. The best part is that you can still get all the pieces for this (unlike many stories 20 years before my youth, which centered around things like large gunpowder fireworks and F-size model rocket engines).
If you were to take a square of aluminum foil, fold it diagonally in half to create a crease, fill the crease with lye (available as Red Devil drain cleaner, among others), and the roll the whole thing up like a... uh... hand-rolled cigarette, and then to fill a (preferably small, 500 mL or less) bottle with a fair amount of water, into which you then place the Drano Reefer before quickly (but firmly) closing the cap and throwing it far, far away, you'd get the Drano Reefer bomb.
The hydrogen comes from the water; the NaOH is merely a catalyst preventing the 2Al + 6H2O -> 2Al(OH)3 + 3H2 reaction from getting stopped by aluminum oxide films, etc. Done right, the gas pressure will rupture the bottle, while the hydrogen produced will add to any flame. For obvious reasons, not recommended for glass bottles.
For an encore, take a metal can (soup, tomato, soda, whatever) and add roughly 1:1 ratio by volume of brake fluid and pool chlorinator (the "shock treatment" is preferred for its high free chlorine content). Adding fluid to chlorinator produces a delayed reaction; adding chlorinator to fluid produces a much faster reaction. Work with the proportions to produce the desired effect - if done properly, you can reliably produce any effect from smoke-only to rapid bonfire. Once you're comfortable with that, you can start working with paper or styrofoam cups to produce a self-immolating container.
Sure. Let's all do this. Let's power up our cars by improvised H2 generators using discarded aluminum cans. Ignore practical considerations such as: does the average household generate enough alumionum waste to cover its energy requirements, prioce and safe handling of sodium hydroxide, disposal of aluminum sodium oxide etc.
Fast forward 1 year. Most people who had started using the aluminum powered cars have abandoned the system.
Why? Not enough waste aluminum generated by the household.
Why? The price of canned soda has skyrocketed.
Why? The deposit on cans has suddenly gone up from 5-10cents per can to %1.50 per can
Why? Canners can't get cheap aluminum anymore
Why? Aluminum doesn't get recycled anymore because it gets burned instead. So canners need to buy "new" aluminum, which costs a lot more. Why? It takes a lot of electricity to refine from ore.
I hadn't known there were so many idiots in the world until I started using the Internet -Stanislaw Lem
You're too quick to dismiss this. As a chemist I'm able to appreciate the simplicity and energy density of aluminum metal. The problem with this and other powerful reducing agents (fuels) is that they are dangerously flammable under the wrong conditions. Nevermind the energy demands associated with producing it - the key is really to heat the aluminium oxide/fluoride ore bauxite up and get it good and melting in a big iron container which serves as the cathode for the electrochemical cell. The anode of choice, at least my best guess is good old carbon or graphite. Yes, it takes a lot of current to reduce the aluminum, but that's the freaking point. It's an energy storage medium. But anyhow, if you have a ready source of thermal energy and/or electricity, like say a nuclear reactor, this is moot. Aluminum is hella lot better to cart around than hydrogen gas ( very poor energy density ).
The idea of reducing/oxidizing a metal for energy is the principle for many existing battery designs, so the idea isn't new. Many of the problems are already apparent in other implementations, like the infamous "exploding" (I doubt they exploded, but they surely burnt hot and bright) lithium batteries.
Indeed, lithium (metal) and aluminum are powerful, energy-dense fuels. Lithium is so reactive (and yet the least among group I metals) that it reacts spontaneously with oxygen in the air while its oxide dissolves in whatever atmospheric moisture it can suck up. Aluminum is probably nearly as electro-positive (I'm not checking a periodic table) and sports three electrons' worth of reducing power relative to lithium's one donor electron. Its self-passivization just might make it the right tool for a bunch of cool applications where lithium and other alkalis are too reactive, too. Unfortunately its a solid and not readily mechanically metered like gasoline so it may be some time before we find it as a direct source of mechanical power in our automobiles, but you never know.
I suppose I should have put the period after "the patent office doesn't care."
Bruce Perens.
Aluminium takes about 15kWh per kilogram to produce. Even if a larger car consumes only half as much mass relative to its own mass, a 1kg RC car using 10g of aluminium would scale up to a 1 ton car using 5kg, or 75kWh, for 20*2/3 miles, or approximately 20 kilomaters traveled, or 325kWh/100km.
For comparison. a Tesla Roadster uses 17kWh per 100km.