Here is a great video showing a giant solar Stirling engine producing 1.5 kw of electricity from a 100C temperature differential between cold water and heat in a greenhouse. 1.5 kw is a lot of energy for a small village and the technology is fairly low-tech.
Peter Lindemann has been talking about the exact same setup for years that you see in the video – you can learn more at this discussion: http://www.energeticforum.com/renewable-energy/10145-scaled-up-solar-stirling.html
