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from the seawater-is-more-than-just-salty-water dept.
There are many ways to generate electricity—batteries, solar panels, wind turbines, and hydroelectric dams, to name a few examples... and now, there's rust.
New research conducted by scientists at Caltech and Northwestern University shows that thin films of rust—iron oxide—can generate electricity when saltwater flows over them. These films represent an entirely new way of generating electricity and could be used to develop new forms of sustainable power production.
Interactions between metal compounds and saltwater often generate electricity, but this is usually the result of a chemical reaction in which one or more compounds are converted to new compounds. Reactions like these are what is at work inside batteries.
In contrast, the phenomenon discovered by Tom Miller, Caltech professor of chemistry, and Franz Geiger, Dow Professor of Chemistry at Northwestern, does not involve chemical reactions, but rather converts the kinetic energy of flowing saltwater into electricity.
https://phys.org/news/2019-07-ultra-thin-layers-rust-electricity.html
More information: Mavis D. Boamah et al. Energy conversion via metal nanolayers, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1906601116
(Score: 2) by Immerman on Tuesday August 06 2019, @02:47AM (1 child)
It's not *entirely* impossible = in a chaotic open system there's always a chance to "cheat" against thermodynamics, but that's really not the way to bet. As a pretty solid rule if you're generating P kW of electrical or mechanical power as a result of your motion, you're also adding at *least* PkW of additional drag, and probably much more. Second law of thermodynamics: you *always* lose.
Consider - if that wasn't the case then you could make a free-energy device by lining an ultra-low-drag ring of pipe with this power generating material, and generate more power than required to keep the water moving.
Now, it might be a viable alternative to driving a dynamo to produce electricity for other ship systems... But given that it would involve exposing a delicate ultrathin skin to the abuse normally seen by a ships hull... I'm going to bet against it.
As a powerstation though - if you could suspend generating plates in big watersacks filled with a sterile saline solution, the agitation from the surrounding water might provide nearly the same energy without exposing the delicate surface to an uncontrolled environment
(Score: 2) by deimtee on Saturday August 10 2019, @07:16AM
I didn't say it was likely, just that it was worth checking out. :)
There is a (very) small possibility that leeching energy from the water would reduce micro-turbulance and increase laminar flow, actually reducing drag as well as generating energy. Do I think it likely? No, but it doesn't violate any laws of physics and the benefits would be large enough to definitely make checking it out worthwhile.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.