Elwin van Beurden describes a futuristic sounding 'antimatter engine' in his essay. This, he says, would only need a milligram of fuel to be able to fly from London to Sydney, and it would do this in less than 1.5 hours. With only a little more fuel we would even be able to fly to Mars. Great! But how does his engine work?

Air enters the engine at the front at high velocity. It is compressed inside the engine and mixed with positrons, or antimatter. When matter and antimatter come into contact with each other, they become pure energy: large quantities of light and gamma rays are produced inside the engine. In turn they heat the air streaming into the engine. Pressure rises, escapes at the back of the engine and generates propulsion.

Van Beurden says that a successful experiment was carried out with comparable nuclear engines in the 1950s. His antimatter engine has the advantages of this kind of engine but, unlike a nuclear engine, it does not produce harmful radiation. The advantages are numerous; aircraft can fly higher, faster and more efficiently. And they do not have to carry large payloads of fuel.

The antimatter can be extracted, according to Van Beurden, from the Van Allen radiation belt or generated in particle accelerators, like the LHC in Cern. If we can draw all the energy needed for this from renewable resources, his antimatter engine would offer an excellent 'green' alternative to today's kerosene-based aviation.

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