Fueling a dream

A chance encounter with an unusual machine in a street market led Pip Hills to explore the fascinating story of an engine invented by a Scottish minister more than 200 years ago that can be powered with whisky – and is now being used by NASA

One Monday evening recently, we had a small party in the Members’ Room of The Vaults. The party was to celebrate the publication of a book which I have had in mind for years and only last year got around to writing. The title of the book is The Star Drive, and the centrepiece of the occasion was a big brass fan which sat up on one of the tables. A dram was poured, a light applied, and the fan proceeded to turn. I should explain…

Forty or so years ago, round about the time I was thinking about what would become The Scotch Malt Whisky Society, I came across a strange machine for sale in a street market in London. I bought the machine, and so began a relationship which would result in this book.

The machine is called a Stirling engine and it is powered by heat: just heat – no oil or gas or steam or electricity or any of the things which we generally use to make things go. The fan runs on the heat caused by burning alcohol – in this case Society whisky. I know it seems a bit paradoxical to power a fan – which is used to keep you cool – by burning stuff, but in India a century ago the only alternative was some poor devil pulling a string but not benefitting from the fan or punkah.

The engine was invented by a Scottish minister of the Kirk just over 200 years ago. It was moderately successful in fairly specialised applications, but not sufficiently, you might think, to justify a popular book about it. And there was a mystery about how, exactly, it worked. Or, rather, about why it worked as well and as badly as it did.

There grew up around the engine a community of enthusiasts whose aim was to make it as efficient as, theoretically, it ought to be – and incidentally, to find out why it wasn’t even less efficient than in practice it was. I know that sounds paradoxical, but the engine is full of paradoxes, which is part of its enduring interest.

People did, now and then, write books about the engine, but they were mostly aimed at folk who already knew about it, and were sufficiently technical to repel anyone who didn’t.

I bought all the books and gradually realised that behind all the technicalities there were some great stories about some really extraordinary individuals, each of whom contributed to the development of the engine.

With NASA’s involvement, it became evident that there was a Big Story into which all of the little stories might fit.


The later 20th century saw various high-tech developments of the engine: solar-powered, nuclear-powered, automotive and so on, but all of them overtaken by other technologies, save in very highly-specialised applications. But in 1964 a brilliant engineer in Athens, Ohio had a moment of insight into the working of the engine. He would spend the rest of his life turning his insight into hardware and software which would perfect the engine as a way of turning heat efficiently into electricity. NASA took an interest in what he was doing and would fund his company to develop his invention to become part of a working KRUSTY: a Kilopower Reactor Using Stirling TechnologY.

This is a fission reactor burning Uranium 235, about the size of a small dustbin. Sitting on top are eight Stirling-engined generators whose power is to be used to propel and guide the vehicle – the starship – away out there in the darkness beyond our solar system.

It’s extraordinary stuff, and science, not science fiction. Try Googling NASA KRUSTY and you will find no shortage of illustrations. The Stirling engine is to be used as the power source for a Moon Base and a Mars Base, though I don’t suppose they will use whisky to make it go.

The Star Drive by Pip Hills is published by Birlinn (£14.99 in UK p&p)

Unfiltered has 10 copies of The Star Drive signed by Pip to give away to lucky members whose names are picked out of the virtual hat. To enter our draw, email with the subject line 'The Star Drive' by 4 February 2022.