[raaaid]

"Shade? Sun? Unfortunately you will need solar cells or any other external power source. Big deal.
Try you get you infos from somewhere else than Wiki."

you dont understand the sterling engine, the best, needs like 20º gradient

this work with 2º which makes it the best thermic engine ever

this is supresed in colleges, its not taught in thermodinamics

with energy you can desalinize water what could solve water problems and hunger