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So many jaded comments! This is incredibly cool. The 'breakthrough' (if you can talk about that at such an early stage) is a few simple materials engineering ha
by aedron 7y ago
So many jaded comments! This is incredibly cool. The 'breakthrough' (if you can talk about that at such an early stage) is a few simple materials engineering hacks:
The nanotubes were easy. Cetindag says the lab just buys them from a chemical supply company. The scientists then add these to a polymer precursor that’s spread into a 6.5-micrometer-thick film. To orient the randomly aligned tubes, the researchers wanted to use a magnetic field. The problem: BNNTs aren’t magnetic.
So Cetindag painted the negatively charged tubes with a positively charged coating; the molecules that made it up were too large to fit inside the BNNTs and thus left their channels open. Cetindag then added negatively charged magnetic iron oxide particles to the mix, which affixed to the positively charged coatings.
When the researchers applied a magnetic field, they could maneuver the tubes so that most aligned across the polymer film. They then applied ultraviolet light to cure the polymer, locking everything in place. Finally, the team used a plasma beam to etch away some of the material on the top and bottom surfaces of the membrane, ensuring the tubes were open to either side. The final membrane contained some 10 million BNNTs per cubic centimeter.
When the researchers placed their membrane in a small vessel separating salt- and freshwater, it produced 8000 times more power per area than the previous French team’s BNNT experiment.
- zozbot234 7y ago> So many jaded comments! This is incredibly cool. I agree. You could use the process to power a desalination plant, and make even more freshwater!
- marcosdumay 7y agoYou need a membrane permeable to negative ions too for that. In fact, I think you'll need that membrane for electricity generation too. Otherwise you will only get to make a single layer of it, what is underwhelming. But it is a large breakthrough.
- chongli 7y agoI think the GP was making a joke. What they suggested strongly implies the existence of perpetual motion machines, contradicting the laws of thermodynamics.
- marcosdumay 7y agoIndeed he is. I'll just post here that it does not violate the second law of thermodynamics. It is a completely real phenomenon that one can verify at home with the ion exchange membranes used to make batteries. (Get some aluminum electrodes, on the scheme salty-fresh-salty water, and add some aluminum hydroxide on the negative side, so you'll have a neutral oxidation and reduction of aluminum on both sides.) What those people created was just an incredibly better ion exchange membrane.
- whateveryou381 7y agoFrom the article the pad produces 30 MW-hr/year/m2. This implies that you need 292533 m2 for this to produce more power than a 1 GW nuclear reactor. For an idea of the scale of this water based power reactor that would produce this energy, I compare to the amount of space required for a large surface area reactor such as a CO2 chemical scrubber. These reactors have effective surface area of about 500sq meters of surface area per 1 meter3 of volume. This implies that you are looking at a reactor that has about 600 meters3 of volume. This is smaller than a typical olympic sized swimming pool, which is about 1700cm3. I don't know if these comparisons are fair, but it implies that there are some questions about heat removal and how it might be as dense of a source as claimed.
- jve 7y agoThe article has since been corrected. > it produced four times more power per area than the previous French team’s >*Correction, 6 December, 11:30 a.m.: This article has been corrected to accurately reflect how many homes a blue membrane could power and how much energy per area it produces.