Terawatt Electrolysis

[matrixscarface]

If there was a terawatt of power running into water as in electrolysis, would it split the water instantly? assuming the ammount was say, 1000 gallons? or at what ammount would it be instant? more or less?

[HydrogenBond]

To split water you don't need a lot of voltage, from about 2-10 volts. At one terawatt of power that is a 100M amps at 10 volt. That puny voltage would not vaporize the water, but would sure make a lot of hydrogen and oxygen in a hurry. If you crank up the voltage, you will begin to ionize the oxygen and hydrogen causing water to reform in a very explosive way. It would be a waste of terawatts, since no useful product might result.

[Jay-qu]

Originally Posted by HydrogenBond

If you crank up the voltage, you will begin to ionize the oxygen and hydrogen causing water to reform in a very explosive way. It would be a waste of terawatts, since no useful product might result.

what if you did this out the back of a space ship? fuel would be water and then you just need a source of this large amount of electricity.. say a nuclear reactor(fission or fusion in the future) Im sure the overall mass of the system would make it not a feasible idea - but thats where ideas start

[UncleAl]

How many joules/sec is a terawatt?
How many moles/second of water will that many joules do

2H2O --> 2H2 + O2

given the free energy of formation of liquid water from the elements at STP?

There is your limiting answer. Don't bother the Forum with questions amenable to simple arithmetic. Spring for a $5 calculator or use the calculator built into Windows.

[Jay-qu]

well I did do the calculations.. but i cant find the piece of paper i did it on.. I had an energy output - but I dont know if that can output enough because I dont know what the overall mass of the system would be

[UncleAl]

but I dont know if that can output enough because I dont know what the overall mass of the system would be

Hell yes you do: per mole.

If the answer is indeed indeterminate, why did you post the question?

[Jay-qu]

I wouldnt say the answer is indeterminate - just to me. And yeah sure I worked it out by mol, but what I really meant was that if is where used as the propulsion of a spacecraft then I have no idea what the overall mass of the ship would be, so I couldnt really tell if that amount of energy would be able to accelerate some large mass x..

[HydrogenBond]

Back in the 1960's there was a blue sky space miltary thought project that was based on the idea of strapping rockets onto large orbiting space boulders and then crash landing them in the enemy's back yard, harbors, etc.. One of the ideas for propulsion was based on hydrogen. If you take hydrogen gas and heat it to almost a plasma state, when it reformsm maybe with oxygen you get this extra turbo kick out the hydrogen. Thism I believe, is the basis for what are called ion impulse engines.

[Jay-qu]

isnt there also a hydrogen slush engine design? like liquid hydrogen that has started to freeze or something I thought we couldnt get close to making hydrogen freeze...

[nkt]

Hydrogen slush is a way to increase the energy density per unit volume of hydrogen as a fuel. The problem with burning hydrogen is that it doesn't have much energy per mole, and so you need a big container full of light fuel to get where you want.

Hydrogen is burned within the ramjet and scramjet engines being designed by the USA military and other groups. It is the best clean fuel for this sort of thing, and leaves a hard to follow trail compared to a gas/petrol burning engine. It also sustains combustion over a very wide range of temperatures, pressures and speeds. In fact, the only downsides are the lack of energy density by volume and the cryogenic tempertures required. (The military don't see cost as an issue, generally. It isn't their money they are burning!)

As for blowing up water with electric, if you add some sulphuric acid to the water, it makes it more conductive, and it might be possible to lower the hydrogen bonding using additives. Certainly detergents lower the surface tension dramatically, and this might have an effect on efficiency.