In reading about all the difficulties faced by engineers trying to build practical electric cars 9short battery life, limited range, long charging times), I wonder if this idea would work? We use metallic sodium and water: sodium and water will release gaseous hydrogen, which you can then use to power an I.C. engine, or a hydrogen-oxygen fuel cell. The sodium you can make from electrolysis of common salt,using nighttime (off-peak) electric power. So, no need for bulky, expensive batteries. Would this work?
Hmmm.
This would be energy intensive, plus you’d get the problem of transporting a metal that is pretty explosive when it gets wet.
I don’t see it working.
Apart from the risks inherent in moving/handling sodium metal (which will eat your skin and burns in contact with water), the disposal of tonnes of Chlorine gas (which will eat you lungs) as a byproduct of sodium production, and the NaOH waste material (which destroys organic material) - and the heat of reaction which needs to be cooled …
No issues at all. :rolleyes:
Plus the efficiency of the cycle will be pretty poor
Si
I remember about a year ago in New Scientist the magazine wrote an article about a similar process involving boron and boron oxide, which is a solid that can in turn be reprocessed into boron using some solar array and magnesium chloride. Aside from needing the water at 800 degree Celsius, would this be an effective solution?
Sure, if you didn’t mind paying about $500K for a tank of fuel. :eek: (Boron’s about $5/gram.)
There’s nothing theoretically wrong with the idea, just practical problems. Sodium has a high energy content, it could be used directly as a fuel for a heat engine. Lithium for example is used as a fuel in boilers for torpedo engines.
While the scheme in the OP would work, reacting sodium with water releases a lot of heat that is essentially wasted energy. (Although whether that is more or less than would be wasted if it were used as a fuel for a heat engine is an interesting question.) A better system would be to use the sodium as the reducing agent in an electrolytic cell, such as the sodium-sulphur battery.
Hydrogen storage has always been an issue for vehicular use, whether the hydrogen was burned in an engine or used in a fuel cell. Chemical generation of hydrogen in situ is certainly one solution under consideration. Such fuels are referred to as “hydrogen carriers”, methanol being the most common. Sodium-and-water combined comprise a hydrogen carrier, just not the most practical one.
So recycle the NaOH and electrolyse it back into sodium and steam instead of using sodium chloride. Efficiency and safety issues probably kill the idea as proposed, but there’s nothing inherently wrong with electrolytic production of metals for energy storage. Try googling “aluminium air batteries” sometime.
matt totally has it. The reaction of sodium and water would be an incredible waste of energy. The byproducts are a serious environmental hazard. If your going to use sodium as a fuel, you want to use it in an electrolytic cell.
The current state-of-the-art for hydrogen storage is in amine-borane complexes. The only problem is getting the hydrogen back into the amine-borane. That is unless you don’t mind your tank heating up to 800 degrees at several atmospheres while pumping hydrogen into it.