Maybe this is obvious, but I always enjoy thinking of it: except for a comparatively little bit of radioactively decaying material inside the earth, and some tidal forces, all energy on this planet, every single joule of energy ever expended is just stored sunlight.<p>Sunlight hits photosynthesizing bacteria which create biological fuel molecules called sugars. Plants store these sugars and convert the energy in them into leaves and roots and organic material. Animals eat the plants and convert the stored energy into useful work. Plants and animals die, and the stored energy in their bodies is consumed by other life which turns them into work. Sometimes it gets captured by the earth before it can decompose and over very long timespans, it gets compressed and turned into super energy dense organic material called coal or petroleum.<p>All the gasoline we're expending, all the coal and natural gas we're burning is just stored sunlight in very efficient organic batteries. Even the wind energy we're capturing is created by the external energy of the sun injecting heat into our earth system and creating work.
This made me realize that there are no lifeforms getting energy by mechanical means (harness wind, waves, tides). That seems like an oversight on evolution's part!
Interesting enough, oxygen (O2) came after cyanobacteria evolved on Earth - there was no free Oxygen until then: <a href="https://en.wikipedia.org/wiki/Great_Oxidation_Event" rel="nofollow">https://en.wikipedia.org/wiki/Great_Oxidation_Event</a>
PDF to non-paywalled article: <a href="https://www.researchgate.net/profile/Olivia_Judson/publication/316561085_The_energy_expansions_of_evolution/links/5b9ced28a6fdccd3cb581926/The-energy-expansions-of-evolution.pdf" rel="nofollow">https://www.researchgate.net/profile/Olivia_Judson/publicati...</a>
Discussed (a bit) at the time: <a href="https://news.ycombinator.com/item?id=14386273" rel="nofollow">https://news.ycombinator.com/item?id=14386273</a>
We can harness the equivalent timeframes of evolution with simple GAs over quick runs (<1m), but we get nowhere near the results. What is the secret sauce?