Stirling engines were commonplace around 1880 to 1920 but fell out of fashion with the advent of the electric motor. But what are they? They are a ‘closed-cycle regenerative heat engine‘.

Lesley Bossine, Ex-top bod at the Kew Bridge Steam Museum, explains “Basically a Stirling engine is unlike a diesel car or steam engine where you have got to put a fuel in. The Stirling engine works on pure heat, so you can power them on solar power, geothermal energy or waste heat.”

Originally invented in 1816 by the Rev Dr Robert Stirling, they are closed circuit combustion engines. They are silent, and work by using heat to warm a cylinder. Within the cylinder, air expands with an increase in pressure that in turn drives the engine.

True Stirling engines also incorporate a heat store called a Regenerator, which stores heat energy during one part of the cycle and releases it later, making it even more efficient.

“The person that can crack Stirling technology and scale it up into a viable energy source will become a multi-millionaire.” says Bossine.

And she’s not wrong…

Here’s how to build one