Whatever happened to the promise of Nitinol engines from the 70's/80's...clean energy from heat differential?

There are many engines that work on heat differential, the Sterling engine being one of the best.

The disadvantage is the small amount power produced.

Because gasoline and diesel contain such a huge amount of energy per gallon, they can produce a lot of power from a compact engine.

The main disadvantage of nitinol was fatigue failure which they never managed to overcome.

It is hard to find an economically viable way of making it produce enough energy to be worthwhile. I can see it as a battery but would have to see a demonstration of it as an engine.

well, there is some new stuff about thermoelectrics https://www.economist.com/news/science-and-technol...