Ignoring the blatant ethical issues associated with this question, I’m genuinely curious from a scientific standpoint how efficient the human body is at generating energy. I’m a chemical engineering major and after learning about combustion engines and steam generation, there’s a great deal of inefficiency. After taking an intro to biochemistry course it seems like the human body is incredibly efficient at energy efficiency, using food as the fuel. I was also made curious by that one black mirror episode where people rode those standing bikes as their job, I think it was for power generation but I can’t really remember. Would it actually be a good substitute in terms of equivalent power and clean energy? Again, a horrible hypothetical given the history and current use of people in such dehumanizing ways, and if this really isn’t something to be discussed, I apologize.
In: Engineering
I guess I’m going to be a naysayer from the other comments, using[ this as my source.](https://phys.libretexts.org/Bookshelves/Conceptual_Physics/Body_Physics_-_Motion_to_Metabolism_(Davis)/10%3A_Powering_the_Body/10.09%3A_Efficiency_of_the_Human_Body#:~:text=Body%20Efficiency,-The%20efficiency%20of&text=Thermal%20energy%20generated%20during%20the,food%20energy%20into%20mechanical%20output)
Obviously we’re talking about “ideal” machines using math but I think we’re all agreeing that car-engine type systems are realistically only about 20% efficient, with the rest of the energy being wasted. On paper car engines could only reach a maximum of about 37% efficiency in an idealized universe of perfection.
The human body’s “chemical engine” runs at about 25% efficiency. Which means we’re actually *slightly better* than car engines and we’re much, much, much better than photosynthesis, which is roughly 2% efficient.
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