This may sound counter-intutitive, but researches have begun a project to build an internal combustion engine (a common car engine) that runs off of solar power. Instead of using gas to ignite everything they want to heat water, add a dash of oil, to create a replacement to the overused pollution producing machine that is one of the leading causes of global warming.
To begin, mirrored parabolic solar collectors would be used to heat oil to a temperature of at least 400 to 700ÂºF (204 to 371ÂºC). This hot oil would then be injected into the cylinder chamber of the engine, just like gasoline ordinarily is. A few microdroplets of water would then also be introduced, which would turn to steam immediately upon contact with the hot oil.
The rapidly-expanding steam would serve the same purpose as exploding gas, driving the piston downward and turning the driveshaft. As the piston reached the bottom of its stroke, the spent steam and oil would exit the cylinder and be run through an oil/steam separator. They could then each be returned to their respective reservoirs, for re-use within the closed-loop system.