Norway building 2MW Osmosis power plant

Capt'n Midnight

Power by mixing fresh water and sea water , which happens anyway when every river meets the sea.

No costs on this yet, but if it's economic then it would be a no brainer for us.


http://www.businessweek.com/news/2013-03-21/norway-regulator-approves-statkraft-osmotic-power-plant-project

Norway’s NVE regulator approved Statkraft AS’s osmotic pilot project, the first in the world to attempt to derive energy from the difference in the salt concentration between sea water and river water.

Actually they've had a test plant running for years, this from 2009
http://www.newscientist.com/article/dn18204-first-osmosis-power-plant-goes-on-stream-in-norway.html

Statkraft, the renewable-energy giant running the project, estimates the total global potential of osmotic power to be around 1700 terawatt-hours per year – about 10 per cent of the world's current electricity consumption.
...
The two liquids are pumped to either side of a membrane, where osmosis creates a pressure equivalent to a column of water 120 metres high. This is used to drive a turbine and generate electricity.

Many of the world's major cities are on river estuaries that could be ideal for osmotic power generation. Unlike wind and solar power, it can provide a continuous source of energy, although seasonal river-level changes do cause some fluctuations.

Macha

Any idea of the efficiency rates?

Capt'n Midnight

Macha wrote: »

Any idea of the efficiency rates?

No.

But one study said could approach 91%

IIRC in theory it's something like 2KWh / m3

In practice there will be pumping losses and losses in keeping the membrane clean.

AFAIK they'll be using half the theoretical head of 270m (it are serious stuff). Or in an Irish context this means that we might pull more power from the rivers than we do with the hydro dams already. Not going to solve our energy problems, but it will help. And it's probably more practical than microhydro since it's a tidal weir rather a dam that you need.


The big kicker is the membrane, at present it's somewhere between 0.5 (pilot plant) and 5 Watts / m2 (commercially viable) , using new materials to make it thinner would help a lot.

Also this technology will most likely benefit from the research into water purification through ultrafiltration. Don't be surprised if someone comes up with a graphene filter that's cheaper and more efficient.


And besides like most renewables efficiency isn't as important as economics. (with wind you can't ever be 100% efficient because you'd have to the air has to have some momentum left or it would all pile up at the wind mill) Solar panels vary hugely in efficiency and we still grow plants even though they are only ~1% efficient because they are so much cheaper than silicon.