wrote:

G. R. L. Cowan wrote:
Perhaps you could take a cue from the Levitated Dipole Experiment,
for fusion plasma confinement, and find a way
to bond hydrogen to the *outside* of a diamond nanofilament.
Less carbon would be required
if it were on the inside, pulling on the hydrogen,
rather than on the outside pushing.


--- G. R. L. Cowan, former hydrogen fan
Burn boron in pure oxygen for vehicle power:
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.html

An interesting suggestion. Amorphous diamond is commonly made
containing hydrogen, though it can be made to remove the hydrogen.
Hydrogen is known to desorb from the amorphous diamond at raised
temperatu

THERMAL STABILITY OF DIAMOND LIKE CARBON THIN FILMS PREPARED USING
PLASMA ENHANCED CHEMICAL VAPOUR DEPOSITION.
http://www.physics.muni.cz/~jzuda/skola/J05385.doc

The report states the desorption becomes significant at 250C and
increases to a high rate at 400C.
According to the report the amount of hydrogen can be 50 at.%. This
means the number of hydrogen atoms is half the total number of atoms,
or the same as the number of carbon atoms. Then since carbon is 12
times as massive as hydrogen, the hydrogen amounts to 1/13th the total
mass, or 7.7%. This exceeds the DOE weight percentage requirements
assuming all the hydrogen could be desorbed.
For the volume requirements, the mass of hydrogen has to be .07 kg per
liter total storage volume, or 70 kg per cubic meter. Assuming the same
density for the amorphous diamond as diamond at 3500 kg/m^3, the mass
of the hydrogen would be .077*3500 = 269.5 kg.

You said you liked the boron paper I link in my signature,
but then you mentioned space propulsion,
which IMO boron is not well suited for.

It doesn't sound to me as though any elemental-hydrogen
storage system can beat a Dewar flask. Consider these numbers:

Per 300 driveshaft kWh, volumes (L) and masses (kg):

108 L 96 kg · Gasoline
448 L 516 kg · Hydrogen, -253°C liquid
972 L 1,222 kg · Hydrogen, 10-kpsi gas
666 L 1,533 kg · Zinc pellets
245 L 331 kg · Boron pellets
208 L 323 kg · Aluminum pellets
??? L 7,880 kg · GM EV1 NiMH battery pack
??? L 12,700 kg · GM EV1 lead-acid battery pack
? 1050 L 2,100 kg · AC Propulsion T-zero Li-ion battery*


If you want to carry energy for energy and hydrogen for water,
I think you'll find the mass saved by going from liquid hydrogen
to boron or aluminum pellets is enough that you can add a
fairly large water tank and still be ahead.


--- G. R. L. Cowan, former hydrogen fan
Burn boron in pure oxygen for vehicle power:
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.html





* http://www.acpropulsion.com/EAASV_101803.pdf , p. 17 of 42