stirling engines are also known as hot air engines. there are different models and systems but i have one that already works with the temperature difference bet

stirling engines are also known as hot air engines. there are different models and systems but i have one that already works with the temperature difference between room temperature and my hand temperature. Awesome. There is a german manufacturer under www.boehm-stirling.com that makes really nice stirling motors in different forms like cars, machines and so on.