fusion

I've had an interest in cold fusion ever since I read Jones' paper (in a fax of a fax of a fax). Pons and Fleichmann's work sounded exciting until you looked at it closely, and it proved difficult (impossible) to reproduce. (I reviewed a more recent work claiming it could happen inside the Earth.) And experiments that seemed to almost get extra energy were already high temperature and pressure experiments that got maybe an extra degree or so out of the apparatus--not something you'd get good heat transfer out of.

Sabine Hossenfelder has a nice overview of the situation, including some updates I'd missed. No magic power breakthroughs seem to be on the horizon, but one hears "That's funny.".