Calculating Power From Hydrogen/Oxygen Flow in Water Turbine

[ANarwhal]

Let's say I had a turbine in water, and I wanted to turn it based on hydrogen bubbling up from the water via electrolysis, how would I calculate the power gained from the flow of hydrogen/oxygen gases through it in a medium of water?

I can calculate the buoyancy of these gases in water fine, and thus the kinetic energy they would have, but I'm unsure how I would translate this to the amount of rotations this would generate in the turbine and thus the power gained. (Also is a turbine the right device to use here? Perhaps a water wheel would be better for gases in water?)

 

[Drakkith]

Why would you want to use electrolysis to generate gas to turn a turbine?

 

[ANarwhal]

Would you accept for fun?

 

[Drakkith]

Would you accept for fun?

Fine by me. Wish I could help you though. I just don't know much about turbines and such. Though I am unsure whether this would really work at all. Can you turn a turbine or something similar using bubbles?

 

[russ_watters]

I can calculate the buoyancy of these gases in water fine, and thus the kinetic energy they would have, but I'm unsure how I would translate this to the amount of rotations this would generate in the turbine and thus the power gained. (Also is a turbine the right device to use here? Perhaps a water wheel would be better for gases in water?)

Such a turbine would not be converting kinetic energy, but rather potential energy. If you can calculate the buoyancy (remembering that it increases as the bubbles rise) and multiply by the distance they rise, that's potential energy. Max energy gained is equal to energy available due to conservation of energy.

 

[russ_watters]

Can you turn a turbine or something similar using bubbles?

Consider an inverted, submerged water wheel...

 

[turbo]

Remember that if you want to calculate the work available at the turbine, you are asking to use hydrogen, which is compressible, and will botch up your calculations.

Water works very well in hydro-dams because water is incompressible and aside from head-losses, friction, and generator-load on the turbine, the work you can get from the T-G set is dependent on the head in the impoundment vs the drop to the outfall. Best of all, the Sun provides the energy to get that water into the river in the first place. No additional energy-input required.

 

[Drakkith]

Consider an inverted, submerged water wheel...

Yeah, but I have this vague feeling that I've seen something like this before on a site for perpetual motion and free energy...that's why I was unsure. Maybe I'm thinking of something else.

 

[KrisOhn]

I think OP is probably looking into the hydrogen car problem. While hydrogen powered cars are very nice to have, the amount of energy needed to perform electrolysis on H2O is more than what you get from burning the hydrogen. If you could take some of the potential energy from the rising hydrogen bubbles and use that energy to power the electrolysis you could make the process more efficient.

 

[ANarwhal]

I am trying to see how much energy I can recover from the electrolysis of water and its subsequent combustion.

One thing I don't understand though, electrolysis at greater pressures seems to indicate the process is more efficient, it seems to me like it should be less efficient in order to not break thermodynamics as the hydrogen runs up the tube. If it's more efficient then the longer you make the tube filled with water and turbines the more energy you should be able to get back (until it either reaches the amount you spent or higher).

 

[Drakkith]

. If it's more efficient then the longer you make the tube filled with water and turbines the more energy you should be able to get back (until it either reaches the amount you spent or higher).

That's what I was thinking, but that can't be right, I just don't know why.