How could non-photosynthetic non-chemotrophic autotrophs create usable energy?

On Earth, the vast majority of the biosphere is ultimately dependent on a large number of autotrophic organisms that produce usable energy in the form of glucose by using photosynthesis. However, on worlds with thick, dense atmospheres or covered in massive sheets of ice, sunlight may not be available to life forms living on either the surface or in ice-covered oceans.

Life, of course, does not need a base of photosynthetic organisms to exist. Chemotrophic life evolved before phototrophs did, and is perfectly capable of living in the most barren and inhospitable environments we've found, like the insides of rocks deep beneath the surface of the Earth. Non-chemotrophic autotrophs do, however, enable a biosphere to expand beyond what can survive on what may be a limited amount of available oxidizable nutrients.

Are there any alternate means by which autotrophic life could harvest energy? In an otherwise habitable world without sunlight, is there an alternate way in which non-chemotrophic autotrophs could evolve?

posted over 8 years ago

ckersch‭

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