https://www.inverse.com/article/35077-wtf-is-zero-point-energy
https://www.cheniere.org/misc/astroboots.htm
This shows a demonstration of the principle. Click on the link to the home page for some highly scientific rambling. Here are links to articles about the principle of the astroboots:
https://www.google.com/search?q=motionless+electromagnetic+generator
One of the links is to a US patent. The device actually works, although they were unable to make a reliable commercial version.