New Chemical Process Could Make Ammonia a Practical Car Fuel 380
A phys.org article says UK researchers have made a breakthrough that could make ammonia a practical source of hydrogen for fueling cars. From the article: "Many catalysts can effectively crack ammonia to release the hydrogen, but the best ones are very expensive precious metals. This new method is different and involves two simultaneous chemical processes rather than using a catalyst, and can achieve the same result at a fraction of the cost. ... Professor Bill David, who led the STFC research team at the ISIS Neutron Source, said 'Our approach is as effective as the best current catalysts but the active material, sodium amide, costs pennies to produce. We can produce hydrogen from ammonia "on demand" effectively and affordably.'"
The full paper. The researchers claim that a two-liter reaction chamber could produce enough hydrogen to power a typical sedan.
Re:Why not just burn the ammonia (Score:5, Informative)
why not just burn the ammonia?
Actually this is possible. From wikipedia [wikipedia.org]:
Ammonia cannot be easily or efficiently used in existing Otto cycle engines because of its very low octane rating, although with only minor modifications to carburetors/injectors and a drastic reduction in compression ratio, which would require new pistons, a gasoline engine could be made to work exclusively with ammonia, at a low fraction of its power output before conversion and much higher fuel consumption
Re:Now I'm confused ... (Score:3, Informative)
Ammonia can be stored liquid at room temperature and pressure, has high storage density (NH3), and is the second most commonly produced chemical in the world.
Re:Wait, *why* couldn't we do this? (Score:5, Informative)
Sure, first hit on Google [archives-ouvertes.fr], gets over 10KW/g of catalyst.
Keep in mind that weight doesn't matter for (solid) catalysts, but surface area does. If you can spread one gram over a square mile's worth of substrate, you get the same catalytic activity as if you used a kilogram with the same area.
Re:waste of time (Score:1, Informative)
They still get 0 miles to the gallon technically...
If they are traveling zero miles on zero gallons then that is zero divided by zero.
When you divide zero by zero (ignoring calculus and limit theorems) the result is undefined, not 0 mpg.
Re:waste of time (Score:4, Informative)
Ammonia is very much renewable. The Haber process is well understood and has been running on an industrial scale for over half a century.
Ammonia is toxic, but it's not THAT toxic. It is certainly less likely to kill you or leave lasting harm than a hydrogen fire/explosion.
The car CAN be fuel cell based, but TFA was talking about reforming a small amount into hydrogen to form a mixture of hydrogen and ammonia that can fuel an internal combustion engine.
Meanwhile, ammonia is much easier to store in liquid form
Re:Now I'm confused ... (Score:5, Informative)
The point here is that to store Hydrogen you need 10,000 psi (http://en.wikipedia.org/wiki/Hydrogen_storage#Compressed_hydrogen) and Ammonia only needs 250 psi in a plastic container (http://en.wikipedia.org/wiki/Ammonia#Storage_information).
They are looking at the following problem
H2O+Energy->H2->H2-Storage->FuelCell->Electricity+H2O
and have worked out that they can do
H2O+Energy->H2,+N2+Energy->NH3->NH3-Storage->H2 +N2 without NOx->FuelCell->Electricity +H20
and what they are excited about is that NH3 storage and transport is a known and solved problem industrially and NH3 cracking is now cheap and clean. Now someone just needs how to work out H2O->H2->NH3 using solar and the problem is solved.
There is also the other issue that a H2 leak is benign or a quick fireball and that an NH3 leak will eat the noses and lungs of everyone nearby.... http://www.wral.com/ammonia-le... [wral.com]
Re:waste of time (Score:5, Informative)
Ammonia is toxic, but it's not THAT toxic. It is certainly less likely to kill you or leave lasting harm than a hydrogen fire/explosion.
The ammonia in your cleaning bottle is hydrous ammonia, which is a fancy way of saying it is mostly water. Hydrous ammonia is pretty tame stuff. Anhydrous (no water) ammonia, like the kind required for chemical reactions, is nasty nasty stuff. If you breathe the vapors it can cause permanent damage to your lungs. If you get it on your skin, you can easilly get a nasty chemical burn. The vapor is flamable and forms explosive mixtures with air. It reacts violently with a variety of compounds.
Anhydrous ammonia is dangerous. Certainly much more dangerous than you seem to think it is.
Re:waste of time (Score:5, Informative)
Myth Busters took this on for a very congested test (also very controlled)
They got somewhere around 180 cars through a traditional 4 way stop, and over 300 through the same space as a roundabout. I was floored it was that great of a difference, they said because at any given time there were multiple cars in the roundabout doing their own thing. (may be off on the numbers, but the roundabout was unbelievably better in their test)
Granted the layout of the roundabout matters a TON, and most I have seen around here are cram a roundabout in a tiny space so you don't REALLY know if the car to your left is leaving the roundabout or continuing...