Yes, it’s true. You can run a car on air – compressed air, that is. What’s more, they were doing it for trains in the mines and to power Parisian trams a hundred years ago. Today, with renewable energy and vehicle emissions top of the green agenda, the air-run car is back in the spotlight. After all, what could be gree ner than clean air?
A compressed air engine works much like a steam engine, except that instead of the pressure created by steam, air is used instead. We know it works. Plenty of companies are working on designing the perfect air-run car, including Honda, who showcased the Honda Air at the LA Auto Show in 2010. So why isn’t the air-run car out there at your local auto dealer? Why aren’t we all queuing up to drive one? The answer is that right now, like so many new technologies, there are pros and cons to deal with.
The pros of the air-run car are obvious. It’s green, clean and there’s nothing quite so free as air. There’s no gasoline, no carbon emissions at all from the exhaust tailpipe, and with a specially designed air compressor you can simply fill up your car at home, although that could take an afternoon. But air service stations could do the job in under five minutes. All sorts of toxic materials, and components made from non-renewable resources are simply unnecessary.
The air-run car is efficient and eco-friendly in other ways too. The air used to power it gets colder as it expands to power the vehicle. This means that, unlike conventional cars, you don’t need an elaborate cooling system to keep the engine at optimum temperature. In fact, the cooling effect can be used to create a low-impact air conditioning system for the vehicle. It all sounds like a dream come true.
Inevitably, there’s a down side, and air-run cars aren’t without some environmental impact, in manufacturing and indirect energy usage. There are still design issues around the wastage of power when it gets converted to mechanical energy. And the bonus of not having to cool the air-run car has the inverse problem: it may actually need to be heated to perform optimally, because when air is compressed it creates heat, but when it cools down it can get too cold. So a heat exchanger needs to be built in, and that uses energy just like other vehicles.
Another problem is capacity. Current air engines aren’t compact enough to power them for long journeys, and high speeds are out of reach. And they do produce emissions, just not from the exhaust. Currently, electric cars are still greener, more efficient. Hybrid air-run plus electric, or air plus combustion engine cars are one possibility for the future.