The HydroICE Project: Developing A Solar Powered Combustion Engine

Fascinating - HydroICE, short for Hydro Internal Clean Engine would purportedly use mirrored parabolic solar collectors to heat oil to a temperature between 400ºF to 700ºF which would be injected into a cylindrical engine chamber, just like gasoline. Add a couple microdroplets of water and presto - steam drives engine pistons; oil/steam would be filtered through an oil/steam separator and then could be reused from respective reservoirs.

They're currently seeking funding via indiegogo.