You can run a Stirling engine on much lower temperature differentials: https://en.wikipedia.org/wiki/Applications_of_the_Stirling_engine#cite_ref-39 https://en

You can run a Stirling engine on much lower temperature differentials: https://en.wikipedia.org/wiki/Applications_of_the_Stirling_engine#cite_ref-39 https://en.wikipedia.org/wiki/Applications_of_the_Stirling_e... https://www.amazon.com/Three-Stirling-Engines-Without-Machine/dp/1452806578/ref=pd_bxgy_14_img_2?_encoding=UTF8&psc=1&refRID=Z2TQKMTYW3NWT3FAF5G7 https://www.amazon.com/Three-Stirling-Engines-Without-Machin...