Osmotic membrane produces 1 megawatt per square meter! - Page 1
Forum section: electronics / general

author: Fungus
author_rank: Super Contributor
timestamp: July 15, 2016, 07:35:18 am
content: This is being reposted like crazy today:http://phys.org/news/2016-07-electricity-salt-three-atoms-thick-membrane.htmlQuote

author: firewalker
author_rank: Super Contributor
timestamp: July 15, 2016, 09:28:26 am
content: As I understand it, at the moment it doesn't produce anything close to 1 Mwatt.Alexander.

author: Kilrah
author_rank: Unknown
timestamp: July 15, 2016, 10:11:58 am
content: I hate that trend of taking any slightly positive result of something that barely works at a tiny scale in a lab and instantly blowing it up to[insert scale that results in huge impressive numbers here]to be able to declarewill be revolutionized soon™ before it's even known whether the thing can be scaled up...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 15, 2016, 11:53:34 am
content: Yes, let's make square meters of 3-atom-thick films, that are robust against environmental forces and biological contamination...I also don't think water has that kind of energy density to begin with, even if you saturate it with salt. It certainly doesn't get that hot, and I can't see a square meter with anywhere near enough volume of water flowing over it being able to deliver that much power. But I haven't run the numbers. I do know there is entropy, and voltage, associated with concentration: but it's quite small, on the order of 10s mV.Tim

author: Kleinstein
author_rank: Super Contributor
timestamp: July 15, 2016, 01:52:27 pm
content: The theoretical potential of osmotic pressure is not that small. As a rough estimate one get something like 20 bar of pressure - so effectively having something like a 200 m virtual drop for rivers of fresh water flowing in a salty ocean. The energy is coming from the temperature - so make the water cooler by about half a degree.The trouble is the membrane. Also scaling could be tricky as the membrane needs to stand a pressure difference in the 20 bar range - relatively easy at µm scale, but difficult at meter scale.I also very much doubt the numbers. For that energy density the water would have to flow at 100 m/s. Don't think this will happen - not large scale, but also not in the micro scale. So maybe someone mixed up mm and miles.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: July 15, 2016, 05:53:10 pm
content: Well, I think they could get 1 mW per square meter.

author: Red Squirrel
author_rank: Super Contributor
timestamp: August 07, 2016, 04:08:22 am
content: They're going to need some nanosuperconductors to transport that massive amount of power throughout the array too.

author: Marco
author_rank: Super Contributor
timestamp: August 07, 2016, 08:09:40 am
content: Presumably you'd put the membrane on an open cell foam as support, so it would only be unsupported over a small distance.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 13, 2016, 09:12:13 pm
content: You can learn all you need about the science underpinnings of this article when the author describes tidal power stations as implementations of osmatic power.I was fascinated for a while by the potential of using the density difference between fresh and salt water for power generation. Run a long pipe from the surface to an appropriate depth, put an osmatic membrane at the bottom and watch the fresh water come pouring out the top. Then I ran the numbers. The physics works, but the ratio of power produced to capitol cost is laughably small. Throw in the required periodic maintenance on the deepwater end and it is only good for a scam fundraising project. It might make a useful desalination approach for locations that have a very deep marine trench close to the shore, but I didn't find any suitable locations that also needed freshwater in my quick survey.

author: gardner
author_rank: Regular Contributor
timestamp: September 01, 2016, 06:51:09 pm
content: The third paragraph:QuoteOSMOSIS is the movement of the solvent (water) across the membrane. The solvent is neutral and nothing weird happens to the charge across the membrane. They are proposing that ANIONS and CATIONS move through the membrane differentially to create a charge separation. I have no idea whether that is feasible, but in any case it's not what OSMOSIS is about.

author: Towz
author_rank: Contributor
timestamp: September 26, 2016, 03:42:23 am
content: Not osmosis. Dialysis. The energy seems to be coming from brownian motion (thermal energy), which is indeed the base for dialysis.