The Car That Makes Its Own Fuel
Spy der Mann writes "A unique system that can produce Hydrogen inside a car using common metals such as Magnesium and Aluminum was recently developed by an Israeli company. The system solves all of the obstacles associated with the manufacturing, transporting and storing of hydrogen to be used in cars. And it's completely emission free."
first post to call bullshit! :: cough ::
Scott
I can produce methane inside my body using only common vegetables such as beans. OK, so it's not emission free.
From the article referenced by the Slashdot story: "The metal atoms will bond to the Oxygen from the water, creating metal oxide. As a result, the Hydrogen molecules are free, and will be sent into the engine alongside the steam."
This is just an example of moving the pollution elsewhere. The metal must be refined, at great cost to the environment. Then it is oxidized in a "pollution free" car.
Actually, a lot of Hydrogen Economy True Believers need to enroll in that same class. Nothing against hydrogen per se, but half the nation seems to think of it as an energy source, which of course it isn't..
Forced hot air from press releases?
The superheated water and H2 come from the magnesium metal reacting with water. The metal oxidizes, gives off heat, and releases the hydrogen part of the water. However, there's still the problem of obtaining the metal in the first place.
Spokesbossy for ominous cow herds everywhere.
Yes, you can get hydrogen out of acids by combining them with metals like aluminium or magnesium -- or hell, even sodium with water. But the cost of refining these metals in the first place is very high.
For instance, aluminium is produced by electrolysis: the ore is dissolved in cryolite, and the pure metal produced by passing an electric current through it. (Details)
There's a number of aluminium smelters in Australia (my home country); at least one of these has its own dedicated power plant, burning brown coal to produce its electricity.
So no, it's not "making its own fuel". The fuel is the refined metal and the acids (or water) that are combined with them to make the hydrogen gas. The fact that burning the hydrogen is what generates the useful energy is irrelevant to this point. The pollution is shifted to wherever the power to make the metals is produced.
When it comes to energy, there ain't no such thing as a free lunch.
I am intrigued by your ideas and wish to subscribe to your press releases.
Sleep is futile.
One thing I've learned over the years: Slashdot editors aren't much interested in science. The publish a lot of pseudo-science articles, or nonsense science articles like this one.
The issue here is that the process works, but it is very expensive in energy, because the metal oxide must be refined.
Anyhow, there is nothing new in the referenced article. The fact that it is possible to produce hydrogen using reactive metals has been known since perhaps 1860, maybe much earlier.
If I remember correctly, there was an explosion in Antoine Laurent Lavoisier's lab caused by hydrogen released by heating with metal. Mr. Lavoisier died in 1794, and not from the explosion.
a) yes Al takes a lot of energy to make. we would call this a "high energy density" material. This is a good thing, not a bad thing.
It would be a good thing if it were true. The massive ammounts of energy used to reduce bauxite are mostly lost as waste heat. If they were actually stored in the material, this might be an efficient system to transport energy.
Water will add to the weight, yes. I don't know all the physics, but in general I know you can get a LOT of hydrogen out of a little water.
Well, I do know the physics involved. No, you can't get "a LOT" of hydrogen from water. Water is only 2/18 hydrogen by weight. So you only get 111 grams H2 per kg H2O. That's elementary chemistry. The heat of combustion of H2 is about 141 MJ/kg (IIRC), and the heat of combustion of gasoline is about 44 MJ/kg. But if you're only getting 11% H2 from water, then the effective heat of combustion from the products of electrolysis is about 16 MJ/kg of H2O. Therefore, even neglecting the weight of the metal, this is not a very energy dense system as you claim it to be.
There so much wrong with the rest of your post, but I don't feel like addressing it. The FP had it right: this is bullshit.