The company is also experimenting with a new way of storing the hydrogen that will fuel its cells a fabric made of fibres of activated carbon that can (when cooled with liquid nitrogen) soak up the same amount of energy per kilogram as petrol.

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Sandals made from plant fibres found at the Arnold Research Cave in Missouri, US, pre-date the shoes from Areni by some 2, 000-2, 500 years.

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To enable this material to store electrical energy, two layers of woven fibres are made into a sandwich, separated by a thin layer of a glass-based insulating material.

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Like traditional composites, Dr Greenhalgh's material consists of woven sheets of carbon fibres which are made rigid using a cured resin.

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