A Stirling engine is a device that converts heat energy into mechanical power by alternately compressing and expanding a fixed quantity of air or other gas (the working fluid) at different temperatures.[1]

Originally conceived in 1816 as a rival to the steam engine as an industrial prime mover, practical use of the Stirling engine was largely confined to low-power domestic applications for over a century.[2] In recent years, the advantages of Stirling engines have become increasingly significant, given the rise in liquid fuel prices and concerns such as peak oil and climate change. Stirling engines address these issues by being very compatible with all renewable energy and fuel sources. The Stirling engine is noted for its high efficiency, quiet operation and the ease with which it can utilise what would otherwise be waste heat and is currently exciting interest as the core component of Micro combined heat and power (CHP) units, widespread adoption of which could have a significant effect upon worldwide energy utilisation.