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5 Running on air ‘The person who follows the crowd will usually go no further than the crowd. The person who walks alone is likely to find himself in places no one has ever seen before.’ – Albert Einstein, scientist
I’m sitting in a London restaurant with a man who, by his own admission, attracts nutters. ‘Pretty much every time I go on TV, the next morning my inbox is full of them,’ he sighs. ‘Perpetualmotion machines, faster-than-light engines, time travel…’ Imagine Tintin in his mid-fifties and you’ve pretty much got Dr Tim Fox, a man often called upon by the media to pass comment on stories with an engineering flavour. It’s part of his role as Head of Energy and Environment for the UK’s Institution of Mechanical Engineers which makes him an easyto-find target for crackpot inventors the world over. So when Tim was called to meet two men peddling a radical advance in an age-old technology, he wasn’t exactly jumping up and down with excitement. Tim entered the wood-panelled George Stephenson room at the Institution’s London HQ and, underneath a painting of the famous man and his Rocket steam engine (something of an omen of things to come), was introduced to Toby Peters and Gareth Brett. ‘I’m thinking “OK, here we go, then, another
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couple of crackpots, ten minutes of my time, I’ll be polite and then I’m off.” My face was a screensaver.’ Three minutes later his cynicism lay in tatters. ‘It was just one of those moments you live for,’ he says, smiling. ‘It changed everything.’
It started in a shed. Indeed, the shed is still there, in Peter Dearman’s backyard, which you can find in the old English market town of Bishop’s Stortford, Hertfordshire. Through its windows you will often see Mr. Dearman, probably with a spanner in his hand. He’s the archetypal shed-hobbyist: jeans, anorak and totally obsessed with mechanical apparatus. His neighbours jokingly used to call him ‘the neighbour from hell’ thanks to the discarded bits of machinery that lay about his property. Today they’re slightly more respectful. As they should be – because, early in 2000, Peter solved a problem whose solution had evaded the engineering world for a century. In doing so, he unleashed a coming revolution that has the potential to save millions of lives. And he did it with a can of antifreeze. Peter’s fascination with all things engineering began as a child. The third of nine siblings, he and his older brother John would ‘do lots of different scientific experiments’ around their parents’ poultry farm. ‘There was the occasional bang but we never really blew anything up – although that was more luck than diligence,’ he admits. When Peter was eleven, John died in a car accident, leaving his younger brother bereft; but within a year, he continued his tinkering, becoming increasingly interested with the problem of resource shortages. ‘I started to think, “How would the world function without oil? How would we get anywhere?” I knew it had to run out sometime
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and I wanted a solution for when it did.’ Not yet a teenager, he started to investigate alternatives to the oil economy – a quest that would eventually lead to him solving an entirely different problem. First he turned to electric vehicles. These were few and far between in the 1960s, although the UK did have a fleet of electric-powered milk floats. Could their battery power be one option for replacing the petrol engine? Peter soon concluded the answer was ‘no’. Batteries simply weren’t ‘energy-dense enough’ – an engineering term for how much oomph can be released from an amount of matter. (This was long before electric and ‘hybrid’ cars began to enter the mainstream. Elon Musk, CEO of Tesla, wasn’t even born when Peter started his investigations.) In fact, the energy density of fuels derived from oil is one of the key reasons they continue to dominate the world – they pack a mighty punch in a very small package. To give you an idea, gasoline is roughly twenty-six times more energy-dense than the consumer batteries you put in a hand torch. Oil company execs like to quote statistics like ‘one gallon of gasoline is enough to charge an iPhone once a day for almost twenty years’. The only fuels we’ve harnessed commercially that are more energy-dense are thorium and uranium. A chunk of uranium taking up roughly the same space as a gallon of petrol would charge your iPhone every day for over forty-five million years. Undeterred, the young Peter Dearman had a look at domestic storage heaters, which, rather than storing energy as electricity, store it as heat. He built his own prototype, warming up a block of concrete, and using the amassed heat to power a small steam engine. His storage heater still fared miserably in terms of energy density compared to petrol, but in building it the thought occurred ‘that you didn’t have to store energy only as
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heat. I thought, “I could use cold. Why don’t I try storing energy as cold?’”’ It’s not an idea that immediately makes sense to most of us. When we think of energy we tend to think of hot things: fire, steam, warm computer batteries … Cold is something we associate with a lack of energy. But our intuition is misleading. Two objects of different temperatures brought into contact will exchange energy (as they try to get to the same temperature) even if those temperatures are both below freezing point – and if you piggy-back on that exchange you can do useful work. Peter, of course, wasn’t the first person to realise this, but he did become the first person, many years later, to use the concept to create a machine that could help to save millions of lives by changing the way our food system works – ‘The Dearman Engine’.
My brother-in-law Mark Smith is a brilliant mechanic, one of those practical types who make you feel slightly unworthy every time you look in your toolbox. He tells me, ‘When it comes to engines, you need to learn the basics and the basics haven’t changed for a long time.’ In fact, engine design hasn’t altered significantly for over two centuries (‘most of what we’ve got today is enhancements that add a little bit of efficiency here, or some more power there – but it’s the same beast underneath,’ says Mark). Perhaps it’s this very lack of change that explains why most of us don’t really know how engines operate, in line with Douglas Adams’s observation that ‘anything that is in the world when you’re born is normal and ordinary and is just a natural part of the way the world works’. Engines just are. In fact, a quick survey of my local pub reveals that, when it comes to their operation, most of us know pistons are involved somewhere
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along the line, but that’s about it. How those pistons are set in motion, or how their movement is converted into useful work, like turning a wheel, we’re generally hazy about. So, some history. The first steam engines were built over two thousand years ago and called either ‘aeolipiles’ or ‘Hero engines’ (after their suspected inventor, the fabulously named Hero of Alexandria). The first engine took the form of a metal sphere filled with water that, when heated to boiling point, sent steam out of opposite facing ‘jets’ on either side of the device, causing it to spin on its axis. Today, we’re more likely to associate the words ‘steam engine’ with classic locomotives like the historic Flying Scotsman, vehicles which provide as good a model as any to understand the basics of how engines work. A heat source (in a steam locomotive that’s the big fire the driver and their mate keep shovelling coal into) warms water in the boiler (the big, distinctive horizontal cylinder at the front of the train that forms the bulk of the engine). So heated, the water boils, creating steam – steam that can be guided through a thin pipe. This piped steam is channelled into one side of a piston chamber. Freed from the constraints of the narrow tube it just came through, it expands into that chamber, pushing a piston (one ‘stroke’). The valve closes and another opens on the other side of the piston chamber, where more fresh steam duly expands and pushes the piston back where it came from (the reverse stroke). Back and forth, back and forth. The sounds that accompany this ballet of mechanics give rise to the distinctive chugging and hissing sounds we associate with steam locomotives. Pulleys and gears can transform the back-and-forth motion of the piston into rotation, driving the wheels of the locomotive. Dearman Engines work on exactly the same principles, except they’re powered not by steam (water gas) but by another gas,
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which, when you first hear about it, seems to make no sense at all. The gas that drives a Dearman Engine is literally thin air.
I’ve come to the Kensington campus of London’s prestigious Imperial College to meet Peter. Now in his mid-sixties (though he looks considerably younger), he immediately strikes me as a gentle soul. If you stuck him in a dog collar he’d make the identikit kindly English vicar. We’re camped in a small office, having just visited a bijou basement laboratory where two newly-minted prototype Dearman Engines have been successfully put through their paces. I have to confess I’d been slightly disappointed. I’d rather hoped to feast my eyes upon a new category of machine, some kind of steampunk/sci-fi crossover, but to my untrained eye Peter’s machines looked unremarkable. The assembled engineers (I counted six crammed into a space not much bigger than a small studio flat), however, all seemed very happy. Everything is going well, they told me. It’s not what the engines look like that counts. It’s what they do. As a stimulus for our chat I’ve brought a photo, dating from the turn of the twentieth century, showing a couple riding a rather flimsy-looking car. The caption describes a ‘graceful little motor-car’ reportedly powered by air that ‘makes absolutely no smell or noise’. The picture is credited to a company founded by Danish engineer Hans Knudsen. It’s doubtful, however, that the car in the photograph was powered by air. More likely it’s an early example of what people in advertising might call ‘aspirational marketing’ – and you and I would call ‘a lie’. Although Knudsen’s company, set up to manufacture airpowered cars in Cambridge, Massachusetts, in 1899, gained
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much media interest, ‘when reporters wanted to see the factory, they were given the run-around from one location to the other. The only evidence produced was a drawing of the car.’ That’s not to say Knudsen was a charlatan. The company made serious attempts to create an air-powered automobile, setting up factories in the UK and the USA. Novel ideas in motoring abounded in the late nineteenth and early twentieth centuries and competed fiercely. Most automotive manufacturers failed, or became absorbed into the few big names that prevail today. Knudsen’s inability to produce a working prototype was almost certainly down to the fact he never had the insight Peter Dearman had over a hundred years later, although he had got as far as converting the air into the right state for use as an energy source – that is, a liquid. It’s hard to think of air as a liquid, but like most substances, air can exist as a gas, a liquid or a solid, if you compress and cool it enough. In fact, air becomes a liquid at about minus 195°C and freezes solid at roughly minus 215°C. What Knudsen didn’t know about making liquid air wasn’t worth knowing. In his brilliant and entertaining book The Romance of Modern Invention,* the Edwardian science writer Archibald Williams describes his 1902 visit to Hans Knudsen’s factory on London’s Gillingham Street, where he was shown around by the man himself. Through repeated rounds of compression (getting to ‘a ton pressure on the area of a penny’), cooling and a smidgen of low-temperature evaporation, Williams described how the molecules in the processed air ‘utterly deprived of their self-assertiveness’ collapsed into ‘a clear, bluish liquid, which is the air we breathe in a fresh guise’. * Full (awesome) title: The Romance of Modern Invention Containing Interesting Descriptions in Non-technical Language of Wireless Telegraphy, Liquid Air, Modern Artillery, Submarines, Dirigible Torpedoes, Solar Motors, Airships, &c. &c.