forums energies: society, ecology and clean technologies

A subject close to my heart: low pressure hydrogen storage

Because I am convinced that with photovoltaic solar, it is the most suitable way to store solar energy.

http://neel.cnrs.fr/spip.php?article1280

The first reservoir based on nanostructured magnesium hydride has just been developed. The hydriding of magnesium is very strongly exothermic, which poses difficulties linked to the management of thermal fluxes. Indeed, the introduction of hydrogen causes a sudden rise in temperature. The equilibrium conditions are immediately reached, stopping the hydrogen absorption reaction. The realization of an adapted heat exchanger made it possible to divide by 4 the loading time. This first tank can absorb 170 liters of hydrogen, with a volume density comparable to liquid hydrogen.

- My vision: a well oriented photovoltaic roof of around 100 m²
- Production: around 20 KW.h annual electricity with current panels (000 times more with future ones)
- Conversion: with an electrolyser performing around 6500M3 of H2 per year

The hydrogen thus stored can therefore supply a fuel cell for electricity, at home or on board, or be used for other direct heating purposes. happiness and energy independence

http://www.futura-sciences.com/fr/sinfo ... hnologie-1
/ d / a-disposable-aluminum-hydrogen-tank_14738 /

Hello
orbs

orbs wrote:http://www.futura-sciences.com/fr/sinformer/actualites/news/t/technologie-1
/ d / a-disposable-aluminum-hydrogen-tank_14738 /

Hello
orbs

I rather suggest:
http://www.futura-sciences.com/fr/sinfo ... ble_14738/

Hello Orbs and Maloche!

Yes, hydrogen ... I rather see obtaining very electropositive metals like Aluminum or sodium by hydrolysis, as you say Capt_Maloche, with solar electricity. It's easier to store and transport

It is then a breeze to make H2 in situ, just add water to the sodium. In addition, it is exothermic, therefore usable also in heat.

Here, watch the video on this link ...
http://ww3.ac-poitiers.fr/sc_phys/cyber ... /NaH2O.htm

@+

Not understand the reaction

it's extremely violent ...

What is it exactly, not sodium anyway?

Si, sodium and water:

Na + H2O -> NaOH + H2

Strongly exothermic reaction, incandescent pieces of Na are projected by boiling water, when the proportion of H2 in the air released by the reaction exceeds the lower flammable limit, there can be an explosion.

Perhaps exploitable in heat, but I suspect that the purification of Na must "cost" much more expensive in energy ...

Hello Maloche,

The reaction is well known to chemists looking for thrills

Na + H2O -> Na OH + 1/2 H2

It is exothermic.

In the experiment presented, the H2 is confined under the board, when it reaches the pressure and the critical proportion starts a reaction with the air:

H2 + 1/2 O2 -> H2O

This heats and blows off the cover, the H2 having not yet reacted ends up burning with the outside air.

So that we can seriously consider in an engine to initially relax hot H2 in a cylinder ... Then in a second time recompress and inject air, classic explosion ...

Full please? No bp, 30 kg of metallic sodium and 50 L of water

rescwood wrote:Si, sodium and water:

Na + H2O -> NaOH + H2

Strongly exothermic reaction, incandescent pieces of Na are projected by boiling water, when the proportion of H2 in the air released by the reaction exceeds the lower flammable limit, there can be an explosion.

Perhaps exploitable in heat, but I suspect that the purification of Na must "cost" much more expensive in energy ...

The purification of Na is in reality a completely conventional hydrolysis of brine (cooking salt). We start by evaporating the water in the open air. Then the salt which becomes liquid is heated to 600 ° C.

PUR sodium is then obtained on one electrode, and pure dichlorine on the other.

Dichlor is a sought-after industrial product for pesticides, and the manufacture of plastics, such as PVC (polyvinyl chloride) and more generally of chlorinated hydrocarbons.

To form solid NaCl, it takes 411 kJ / mol, or to dissociate it as much + heating energy to pass it to the liquid state (for example with solar concentrators or a little biomass to burn).

The energy of Na + H2O -> NaOH + 1/2 H2 gives back 184 kJ / mol

Combustion with air 1/2 H2 + 1/4 O2 -> 1/2 H2O
again gives 143 kJ / mol

So with a little solar energy, it goes quietly

Reminder: solar energy = 10 times the current anthropogenic consumption of energy

What to meditate

Ah? interresting

you could make a freehand crobard of the solar process that you describe with T ° and masses / flows in play?

Please?

Not immediately Captain, not immediately!

On the fact:

PRODUCTION

Step 1: extraction of salt in full sun by evaporation of sea water

Step 2: heating by ecological means of salt. Wood or cylindroparabolic concentrator with heat transfer fluid ... Ultraclassic

Step 3: immerse 2 electrodes supplied with direct current / voltage, collect the chlorine bubbles on one, and the liquid is concentrated in pure sodium, especially at the other electrode

Step 4: pour the still liquid sodium into small ingots, let it cool!

CONSUMPTION

1 / In your toto, you fill up with water and sodium ingots

2 / A reactor is built where water is squirted under pressure on the sodium, the Na is attacked and produces soda and gaseous and hot H2

3 / we relax it all in a pre-bedroom

4 / We re-inject all this into the main bedroom at maximum volume

5 / We compress, we balance air: explosion

6 / We recover water, NaO, Na2O oxides, and sodium hydroxide

7 / the soda condenses with the water in the exhaust and is recovered

8 / when you fill up, you give a can of soda that can be used directly in industry.

Here is Capt_Maloche my idea ... And all this can be done with my PRBC engines ... for their compactness and the extreme flexibility of use of each room ... Hydrogen storage is nice, but I think that vsis far from perfect and for a long time.

And I am impatient for a lot of reasons about it ...