[alancalverd]

Can i sell them some liquid hydrogen too?

If you can make it at a competitive price, there is a growing market not only for rockets but also cars. Get ahead of the curve and make a fortune!

[vdblnkr34 (OP)]

Not a bad Idea. Probably can be used liquid nitrogen solution as refrigeration system.

Can I build hydrogen compressor to liquid on my own?

[alancalverd]

Not a bad Idea. Probably can be used liquid nitrogen solution as refrigeration system.

No. Nitrogen boils  at 77K, hydrogen at  20K.

Can I build hydrogen compressor to liquid on my own?

Other people have, so why not? Or just buy one and save the research and development cost. H2Prime, Linde and AirLiquide, for example,  all manufacture the kit in various sizes and have years of experience.

[vdblnkr34 (OP)]

I just looked at NASA website and found that they also buy CO2.

That's funny.

[dervid30]

Hello, you can pump O2 and H2, I also pumped it and it was fine, so if you want, yes

[vdblnkr34 (OP)]

What is better. To modify internal combustion engine to run on hydrogen/oxygen gas or power the steam engine using hydrogen/oxygen burners?

[wolfekeeper]

NASA pays less than $4 per kilogram for liquid hydrogen, with pretty much the same potential combustion energy as a gallon of diesel, in about twice the volume and a quarter of the weight. Totally feasible and competitive.

They get it from steam reforming methane though and it generates shitloads of CO2.

[vdblnkr34 (OP)]

How difficult to convert propane gas engine to a hydrogen gas engine?

[wolfekeeper]

May be quite easy, provided it's not made of metals that are easily embrittled. Hydrogen is very easy to burn. You'd have to change the jets/carburettor/injectors whatever.

[vdblnkr34 (OP)]

Can i power steam engine by burning hydrogen with oxygen or without?

Could be that better than internal combustion?

[Bored chemist]

NASA pays less than $4 per kilogram for liquid hydrogen

They could buy about 140Kg of crude oil for about $90 ( the oil price is quite high at the moment).
So that's about $1.5 per Kg.
That 1Kg of oil provides about 42MJ of energy when burned.
So that's $.036 per MJ
A kilo of H2 provides about 140 MJ

And that's about $0.029 per MJ


Or they could use methane
It's about $5 per million BTU
1 BTU is about 1 KJ
1 million BTU is about 1GJ
So, it looks like gas is really cheap.

Or, in the UK £2.2 per therm 
and 100 MJ =1  therm
So your $4 that you pay for a kilo of H2 would get you about 250MJ of energy as natural gas.
You can see why someone might want to run a rocket on natural gas.

But it's beside the point.
The fuel is a tiny fraction of the cost of a rocket.
Building a pump that will deliver the volume of LH2 needed is more difficult than building one for kerosene.
Not least because the density of H2 is low, so you need to shift large volumes of it and you have to pump that volume into the rocket against the back-pressure of the rocket engine. Pressure times volume  = energy.
So the energy (or power) cost of pumping is directly related to the volume that you need to deliver.
A kerosene pump can have a much lower power requirement than a LH2 pump.

It's quite likely that NASA already thought of these things.

[vdblnkr34 (OP)]

That's a very precise calculations. Burning hydrogen is more efficient?

[alancalverd]

A kerosene pump can have a much lower power requirement than a LH2 pump.

It's quite likely that NASA already thought of these things.

So why do they use hydrogen rather than kerosene?

[Bored chemist]

That's a very precise calculations

Not really.
That's why I used the word "about" so much.

So why do they use hydrogen rather than kerosene?

Because it has a higher specific impulse- even though it's a nuisance to use.

[wolfekeeper]

Liquid hydrogen is good for upper stages, less good for lower stages (although it works). The low density increases the size of all the pipework and pumps and tanks so the thrust/weight ratio for a hydrogen rocket is a lot worse and this cancels out the effect of the higher exhaust ratio- the stage delta-v is about the same. Still, a hydrogen fueled upper stage is lighter, and this makes the lower stages smaller and cheaper.

That's mostly why the second and third stages of the Saturn V were hydrogen fueled, but the first stage was fueled by kerosene; and it's why the Space Shuttle took off on about 90% solid rocket booster thrust.

[Iannguyen]

The statement is pretty intriguing; the use of the individual gases of O2 and H2¬ is in itself the most creative question. You can definitely, work on this but would need it in bulk to fuel your car and carry out any operation.
To make the gases work, you will need to get them in compressed silos, with hundreds of thousands of tons of this gas available. The better solution would be getting these gases in a liquid, which will likely provide more of the gases, yet making them available and storing them would be an issue, but this will probably make your car run long distances. If you work on that figures in liters and mole of the gas, it will be about 22.4 liters @STP, which means you will have 22.4 liters of the gas in liquid state (most fortunate case) to make it at one mole, which will keep your car running for long.

[zanewiller]

Also should be good to burn oxygen with hydrogen together?

[alancalverd]

https://www.cittimagazine.co.uk/news/electric-vehicles-charging/hydrogen-vehicles-arrive-at-teesside-international-airport

is worth a visit. Not that people who run commercial airports know anything about engineering or economics, of course.