I have an idea about a planet that is cold and dark, but very loud. Constant rolling storms, crashing glaciers and icesheets, earthquakes, volcanoes and so on.

Instead of photosynthetic plants, as on Earth, I was considering whether it would be plausible to have some sort of phoNosynthetic life, i.e. an organism that can convert sound energy into chemical energy.

This is basically a chemistry question then. Is it conceivable that there could be a process where this would work? Are there existing chemical processes that are known that use sound waves to store energy? If so, what sort of sound are we talking about? Ultrasound? Infrasound? Could a planet actually remain that consistently loud without eventually calming down?

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    $\begingroup$ Sound actually has a very low level of molecular energy compared to, say, heat. You're more likely to evolve "plants" that extract energy from a heart gradient than a sound gradient. $\endgroup$ – Isaac Kotlicky May 29 '17 at 23:00

Sound of whatever wavelength transports energy, so in principle it should be possible to collect it and store it. There's been some work on that recently. For example, in 2014 "researchers in London… developed a device that uses sound to help generate an electrical charge… [using] the piezoelectric properties of zinc oxide (ZnO) nanorods to harvest energy from vibration and movement." There are a few other pieces of research in that vein, mainly aimed at the possibility of recharging cellphone batteries.

The problem is that the energy density of natural sounds (or random artificial sounds such as street noise) is very low:

What the human ear perceives as clanging cacophony — the roar of a train engine or the whine of a pneumatic drill — only translates to about a hundredth of a watt per square meter. In contrast, the amount of sunlight hitting a given spot on the earth is about 680 watts per meter squared.

Tapping the vibrations transmitted directly by physical objects would be an indirect way of getting energy from sound. Again, this would be a very small amount of energy. And you'd have to be able to justify how an environment can become and remain so noisy for sound-energy-harvesting organisms to evolve.

Piezoelectric organisms may find it useful, instead, to get some energy directly from movement, e. g. in the "roiling storm" scenario.

  • $\begingroup$ Thanks for adding the distance and proof to my comment. :) sounds are just motion, and molecular level vibration beats packet motion handily when it comes to energy density... $\endgroup$ – Isaac Kotlicky May 29 '17 at 23:32
  • $\begingroup$ You are making it sound as if the oldest trick in the book was invented in '14. You get an upvote just for that $\endgroup$ – Raditz_35 May 30 '17 at 12:42
  • $\begingroup$ "...a device that uses sound to help generate an electrical charge…" AKA a microphone. But there's a reason microphones are usually connected to amplifiers :-) $\endgroup$ – jamesqf May 30 '17 at 17:15

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