Wow, that is amazing! Lots of other cool stuff on his website I'll be looking at too.
My dad built a 1 cyl Stirling back in the '70's from a kit. He didn't like using an open flame to fuel it so he fabricated a solar reflector dish & could run it on sunlight only. It wasn't very powerful but the concept worked. He was thinking if he could build something like it on a grander scale, he could make a auxiliary motor for a sailboat that never needed fuel. He could sail around the world for free!
It never did pan out but he had a lot of fun working with it & dreaming about a round the world trip.