Geothermal doesn't really convert small deltas into power. It takes a small delta, then amplifies it using compression/expansion to alter the temperatures into a usable delta. So it is subject to all sorts of inefficiencies as it compresses/expands/moves the medium around.
The real breakthrough would be a machine that can harvest power without a temperature gradient/delta, something that could take the vibration of molecules and convert it directly to electricity. Something like this...
"The idea of harvesting energy from graphene is controversial because it refutes physicist Richard Feynman's well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado's team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible."
> "The idea of harvesting energy from graphene is controversial because it refutes physicist Richard Feynman's well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado's team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible."
The crucial question here is: Can this alternating current do work?
Without overwhelming evidence there's no reason to think this isn't just another mirage like emdrive. The second law has stood up to everyone everywhere who ever made a machine being on the lookout for a single counterexample starting from well before we had science.
The real breakthrough would be a machine that can harvest power without a temperature gradient/delta, something that could take the vibration of molecules and convert it directly to electricity. Something like this...
https://www.youtube.com/watch?v=KiLTEjm8zLw
https://phys.org/news/2020-10-physicists-circuit-limitless-p...
"The idea of harvesting energy from graphene is controversial because it refutes physicist Richard Feynman's well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado's team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible."