Be Excellent To Each Other

brackish water as found in tidal rivers and their estuaries?

Malc

Fuck all?

Oh, LOADS, but I'm not telling

CALLING GAYWOOD THE MOONPRINCE!

I REPEAT, CALLING GAYWOOD THE MOONPRINCE!

You hum it, I'll play it.

Demineralisation.

Only that it is dependent on large volumes of sufficiently efficient semi-permeable membranes with high flux and salt retention...











Ok - I lied. I know nothing about it, and I got that tidbit from here: http://www.sciencedirect.com/science?_o ... ba2c362297 and I'm not paying $31.50 to read any more about it.

I know a fair bit about osmotic pressure and its use (and advoidance of abuse) in biological systems.

have you tried turning it off and back on?

It's like the opposite of a desalination plant right? I read something about that years ago.

Here's a nice non-chemistry description of how it works:
http://www.statkraft.com/pub/innovation ... _works.asp

I think I remember it needed a bit of a heat source to get much power out of it. But anyway.

Why you ask?

I just caught a bit of "coast" and they were talking about some Norwegian Gas pipeline supplying us 20% of our Gas, and it being able to do that for at least 40 years, and then they mentioned that a potenital alternative was to use osmotic pressure.

they showed an egg soaked in vinegar to remove the shell, and then soaked in water for 24 hours, it had swollen in size, and when a pin was stuck in the albumen (spelling?) a nice little fountain of water spewed forth.

The presenter then explained this was because the egg white was a membrane, it let in the water, but did not allow anything out, this, the viewer was told, was osmosis. The because the egg was swollen the pressure inside the egg was greater (Osmotic pressure).

Next we were told that sea water and pure water could act in the same way, and some construction with 7 chambers was shown. ( I will attempt an ascii diagram below)



The | is the membrane this allows river water into the sea water chamber, so the pressure builds up and heads along a pipe and turns the water wheel in the bottom right, this is apparently the same pressure as found at the bottom of a 270m waterfall!

I read somewhere that we could be looking at up to 1 or 2 PW of power a year could be produced using this method and the worlds tidal rivers, with only brackish water as a by product.

Malc

Mohh. I had no idea you could generate electricity from osmosis, although I can see the logic behind it. Doesn't seem like it would generate much though, although Malc's number there is very large indeed.

Awesome if they get it to work, eh!

Those facts, and more, are in the pdfs on the link I gave above.

That number is "all the rivers in the world x our invention". You can do the same with wind or tidal power or anything else repeated on a vast scale...

So far they're building a 10kW demonstration plant. Don't know if it's working yet.

AKA more "blue sky" thunking, that'll eventually turn to nowt as impracticable, inefficient and just no bloody good and we'll be back to nuclear before you can say "What a waste of bleeding effort that was."

If only we could combine all these alternative methods of energy generation, or better yet find an efficient way of extracting hydrogen from water - then, just then, we might just have sustainable power.

This is, of course, also exactly what people were saying about nuclear in the '50s.

I read about this in New Scientist about 6 months ago. Seems really interesting. It was one of their two-weekly "GLOBAL WARMING IS KILLING US ALL" specials.

There's less engineering challenge involved in this than there was in the development of commercial nuclear power.
It's all down to whether the membrane can be manufactured precisely and affordably enough, and lasting well in operation. The rest of the plant is basic hydraulic and structural engineering. Far simpler, safer and with no waste to deal with. It's worth a *lot* of investment to try to get it viable.



Combine? You mean as in fund, develop and exploit all of them? Yes, I agree.