It's a Clean Engine?
We hear a lot about car and lorry traffic polluting our streets.

The problem is that the internal combustion engine explodes the fuel inside the cylinder. This is done so fast that the combustion is not complete. Ideally, the fuel would be turned into water and carbon dioxide.
With engines running at thousands of rpm – even 2000 rpm is 33 explosions per second – there isn’t enough time for “complete” combustion. As a result carbon monoxide is created – not carbon dioxide.
If you run a petrol engine inside your house – it will kill you with the carbon monoxide.

The Stirling engine achieves complete combustion. No carbon monoxide. This is because the combustion is external to the cylinder and piston. This is the external combustion engine. The cylinder is heated from the outside by a blue flame. The gas hob in your kitchen has a blue flame. This is the sign of complete combustion. When carbon dioxide is formed, blue light is given off. By contrast, when a yellow flame is seen, this is hot carbon granules – soot – glowing whilst they cool down. There is not enough oxygen being supplied to enable proper combustion.

Yes, ventilation is needed around gas hobs – carbon dioxide can get the better of you. We breath in oxygen and then exhale carbon dioxide. We don’t need an excess of carbon dioxide.
Keep your Stirling engine ventilated.

A Stirling engine is one of the few engines that is clean enough to be able to run inside your house. Back in 1910 the Swiss made a gramophone which was powered by a Stirling engine.
The “Maestrophone” was used to provide pleasant hours of music inside your home. Have a look at the You Tube video above.

The Stirling can go further in terms cleanliness. Some of them run without oil lubrication. Compared to the petrol engine, the forces are far less and the temperatures are not so extreme.
There is no need for oil lubrication. Low friction materials can do the job.

So no carbon monoxide and, sometimes – no oil.

The same as us – we, and the Stirling engine both produce carbon dioxide.
But unlike us, – that’s all it produces!