Sodium-Water to make H2 Fuel For Cars, can this be true?

[djeenius]

Hello,

I found from a mythbusters forum
under a new energy discussion
http://www.mythbustersforum.com/viewforum.php?f=8 (there is a poll to vote)

discussion about using cheap sodium and water
http://www.mythbustersforum.com/viewtopic.php?f=8&t=11

to generate hydrogen.
This could be used to run cars on regular water.
They don't claim overunity, but sort of battery use,
if the explosive nature of the reaction
could be mechanically controlled.

The over unity discussion on that site was quite sceptic
so I assume this could have a realistic point. 

[triffid]

Sodium metal(i don't think its cheap) will react violently with water to liberate hydrogen but its hard to control.It is not overunity.Triffid

[djeenius]

Thanks for quick and smart reply.

As you point out price of sodium in the metallic form (not salt!)
is definitely a key issue.

I did also some research

It would appear that sodium might not be too expensive compared to the extreme energy contents.

A link about extreme reaction
http://www.periodictable.com/Stories/011.2/index.html

I found price of 13 EUr /kg in 50 kg scale,
http://www.special-metals.com/sodium.html

One coulld assume that in ton scale the price would be a fraction
of this. Assuming that it would not need to be pure
but potassium and earth alkalis from sea water would also work,
this may allow price level of a few, may be 0.5-5 Eur /USD /kg ??

The reactions of sodium are exremely violent so huge amounts of energy can
be released.
Would need to find exact reaction energy, any ideas?

Part of the energy is in form of Hydrogen gas exploding from the
heat of reaction. H2 is obtained as about 1 /23 (ratio of atomic weights)
part of mass sodium,  based on  reaction(2 Na + H20 -> 2 NaOH + H2)
giving amount of about 50 grams or 25 mol  (about 550 liters).
H2 energy content can be considered.

Building a machine using this reaction would be require some creativity.

[fritznien]

Thanks for quick and smart reply.

As you point out price of sodium in the metallic form (not salt!)
is definitely a key issue.

I did also some research

It would appear that sodium might not be too expensive compared to the extreme energy contents.

A link about extreme reaction
http://www.periodictable.com/Stories/011.2/index.html

I found price of 13 EUr /kg in 50 kg scale,
http://www.special-metals.com/sodium.html

One coulld assume that in ton scale the price would be a fraction
of this. Assuming that it would not need to be pure
but potassium and earth alkalis from sea water would also work,
this may allow price level of a few, may be 0.5-5 Eur /USD /kg ??

The reactions of sodium are exremely violent so huge amounts of energy can
be released.
Would need to find exact reaction energy, any ideas?

Part of the energy is in form of Hydrogen gas exploding from the
heat of reaction. H2 is obtained as about 1 /23 (ratio of atomic weights)
part of mass sodium,  based on  reaction(2 Na + H20 -> 2 NaOH + H2)
giving amount of about 50 grams or 25 mol  (about 550 liters).
H2 energy content can be considered.

Building a machine using this reaction would be require some creativity.

according to http://www.shec-labs.com/calc/fuel_energy_equivalence.php
550 L of  h2 is = to .17 L of gasoline
not cheap imho
you can also do this with aluminium but same problem not cheap

[triffid]

Calcium metal and potassium metal react violently with water too (just like sodium metal) to liberate hydrogen ,leaving the hydroxide of the metal behind.However CaOH
does not dissolve well in water( can be found in whitewash) whereas NaOH and KOH will.Triffid