[kolm]

Osmotic power means you benefit from osmotic pressure. Statkraft (Norway's main power producer) will actually build a "power plant" of some kW capacity:

http://www.statkraft.com/pub/innovation ... /index.asp

http://www.statkraft.com/Images/Osmotic ... 4-8796.pdf

Estimated potential is 1700TWh per year, which would mean a realistic potential of maybe 200TWh/y, worldwide, with maybe 25TWh/y potential in Europe. Costs estimated somewhere between 5-10c/kWh, which realistically means something like 12-15c/kWh. Still, nice to see serious guys work on an underdeveloped and rather elegant alternate concept.

[steam_cannon]

Huh, I'm surprised, I hadn't heard about that concept before.
Looks interesting, thanks.

How osmotic power works
In an osmotic power plant, we feed freshwater and seawater into
(LARGE) separate chambers, separated by an artificial membrane. The salt
molecules in the seawater then draw the freshwater through the
membrane, causing the pressure on the seawater side to increase.
This pressure corresponds to a water column of 120 metres, or a large
waterfall, and can be utilised in a turbine which generates electricity.

An idea dating from the 1970s
The idea to generate power through osmosis originates from the
1970s. At the time, however, the membranes were not very
effective and power prices were too low to enable anyone to
profitably invest in such a project.

http://tinyurl.com/6fwfbp

So it's not cheap energy, but it works. Sounds like a
technology to keep an eye on as energy prices keep climbing...

[mos6507]

This looks like just a way to do hydro power without requiring big vertical drop. The cost of setting up such a huge amount of membrane would be pretty high.

[kolm]

This looks like just a way to do hydro power without requiring big vertical drop.

Except that it is completely different in almost every aspect, yes.

[oiless]

Reading what they say on the website it appears any application is several years away at best, and by no means a sure thing.

"Performance improvements needed
The prototype will demonstrate that osmotic power actually works, and will be used to test the technology itself. The biggest challenge lies in developing a membrane which draws enough water through to create an effective pressure to drive the turbine. Only once membranes with a particular efficiency have been developed will osmotic power become a competitive source of renewable energy. Since Statkraft became involved in 1997, the performance of the membranes has been improved many times over. A commercial plant the size of a large football stadium could be ready as soon as 2015 if Statkraft succeeds with the project."

They also say that the prototype is expected to generate enough electricity to power a hot plate. Sounds like a very infant technology, even though it has apparently been under development for over ten years.
A cynical mind might think that the main thrust is to get research and development grants, a working product might be a fortuitous accident if it happened. But then I'm a cynic.

[kolm]

Reading what they say on the website it appears any application is several years away at best, and by no means a sure thing.

Yeah, that's what they say. However, I know some of those guys, and they are quite down-to-the-earth. They believe (in an engineer way of "believing", not an entrepeneur way) in the general feasibility of the stuff.

Anyway, I mentioned it because it is exotic, genuine, physically possible and a nice twist, not because it will power our cities in ten years.

A cynical mind might think that the main thrust is to get research and development grants, a working product might be a fortuitous accident if it happened. But then I'm a cynic.

What, you doubt the guys who invented starpower?

http://www.youtube.com/watch?v=hgbtVR2Qrco

Seriously, this is a state-owned company with little possibilities (and even less incentives) to get any grants whatsoever. They persuaded management to finance a toy, er, model plant, and are happy with that.