Besides its standard uses such as cooling and freezing, dry ice has a number of interesting applications. Below is an example of how dry ice can help explain physics and the properties of air temperature:
A Stirling Engine operates when a difference in temperature is created between its two conductive base plates. The space between the two plates is sealed and contains a fixed amount of air. Because the engine is sitting on a block of dry ice, the temperature of the bottom plate drops and the air around it contracts. This draws the piston on the top plate down into the sealed reservoir and spins the attached flywheel.
A reverse effect can be attained when the engine is placed on a heat source: the air at the bottom of the reservoir expands, pushing the piston away from the base plates. It is not new technology, and it may not be the solution to the fuel crisis, but it certainly presents an interesting take on alternative forms of energy.