It takes many years to train it though
Now you know why you always see new doctors
(This is also why LLMs passing medical exams, though impressive, has not rendered the profession obsolete: LLMs are book smart, but don't have the implicit knowledge that we humans only gain from practical experience).
With a SOFC topping cycle they might approach 70-80% efficiency. SOFC with just a combustion turbine (no steam bottoming) could exceed 60%. Granted, SOFCs are direct chemical->electrical conversion, but their waste heat is very usefully hot.
I don't think it's entirely a coincidence that nuclear power plants in the US stopped being built about the same time combustion turbines (by themselves, without the steam bottoming cycle) reached efficiency parity with high temperature steam turbines.
(SOFC = solid oxide fuel cell, which operate around 1000 C.)
("Lower heating value" is based on energy that could be obtained burning natural gas to CO2 and water vapor. An additional 10% could be obtained by condensing the water vapor to liquid, this is "higher heating value".)
What's even more shocking is that conversion of food to energy period is ~90% efficient, which is crazy to me. The fact that you can burn food and measure the energy given off, and that's very close to how much energy you get from eating it- that's insane.
The efficiency of the human body is all over the place. Muscles are only ~30% efficient, and the rest is waste heat... but humans walk using orders of magnitude less power than any walking robot. As far as I know we have never made a powered walking machine that is 10% as efficient as a person. The only way we can beat it is with a carefully balanced, specially-lubricated pair of legs that is leaned downhill on a treadmill and powered by gravity.
Beating human locomotion in the general case is pretty far off. It's a combination of body plan, extreme optimization of joints and energy storage, and really good algorithms.
One killer feature of the human body is synovial fluid. It's very thin, non-newtonian, self-replenishing and contained in particularly low-friction bearing surfaces. It's certainly better than 99.9% of mechanical joints, because these surfaces filter, heal and re-lubricate themselves. Mechanical joints have sticky grease so they stay lubricated without maintenance, and work in the presence of water and grit. It's doubtful that any joint that doesn't heal itself can compete, long-term.
[1]: https://spectrum.ieee.org/durus-sri-ultra-efficient-humanoid...
The brain is running on 20W of power and it has the best LLM, the best robotics control unit, very good sensor integration and all the other exciting stuff which we* want** AIs to have. I'd rather have that than nuclear powerplants feeding data centers.
* overreaching a bit
** also not really true for everyone