Friday, October 2, 2009

The second movement.

This is an addendum of sorts to 'The harmonies and the synchronies'.

That’s a Delta IV launch vehicle in its ‘Heavy’ configuration taking off. The pretty lights under it are shockwaves cascading through superheated water. (The engines use H2/Lox – the exhaust is almost plain water. Albeit, vaporized and partially ionized)

Tell me again why science isn’t the most awesome thing ever?

The picture was sourced from http://gizmodo.com/5372241/this-insane-photo-destroyed-a-camera-lens and it was taken by an awesome dude named Ben Cooper

2 comments:

Ketan said...

The pic is actually cool!

Yes, hydrogen and liquid oxygen as fuels are great things. I'd heard of hydrogen cells, which also work on the principle of oxidation of hydrogen, which I think is most exothermic chemical reaction known, right?

But I wonder, if we could find economical techniques to accumulate hydrogen. Electrolysis of water would be economically effective only if it would not require one of the fossil fuels/energy source we're already using! Of course, I'm speaking in context of current/future energy crisis, which you didn't directly deal with in your post, but probably had in your mind.

Any further ideas/information you have on the issue?

Harshad Srinivasan said...

Technically, Hydrogen and Florine yield the most exothermic (or energetic) reaction. But Oxygen is much easier from an engineering perspective and is nearly as good.

Fuel cells utilize H2 and O2 in a very similar way (i.e. 2H2 + O2 = 2H20) but the science is quite different (and the process is much more efficient). But for raw power, its nearly impossible to beat a giant H2/O2 powered launch vehicle. (A large one puts out more power than small nations!)

'Cracking' water to produce Hydrogen takes as much energy as a fuel cell can put out (actually, it produces rather less because of efficiency issues).

That's why H2 isn't so much an energy source as an energy storage medium - you use solar/wind/whatever to 'crack' water into H2 and O2 whenever those sources are available and then use the H2 in a fuel cell as a battery for an end use.

This way, you achieve much much higher efficiencies and power densities as any current battery technology.

The problem is one of engineering now and not basic science. In other words, its only a matter of time before your laptop runs on H2 and doesn't run out of power for a week.