Car plant – The Engineer Online
Low-carbon motoring usually conjures ideas of energy-efficient engines, alternative fuels or …electric cars…. But although the powertrain forms a large part of the car’s carbon footprint, it is not the whole story. The embodied energy in the vehicle — the energy, and associated carbon, that goes into making the car and its component materials —is also a small, but significant, proportion.
A recent study by Volkswagen estimated that almost a third of a car’s carbon footprint comes from its manufacture. These figures do not include the energy or carbon needed to make the steel or the electricity used in the factory. Finding new, lower-energy materials is a target of research projects across industry and academia, and some striking results have now started to appear.
At the Warwick Manufacturing Group, Ben Wood recently led a project to produce an ‘eco-racing car’, made as far as possible from natural materials. Starting with a steel tubular spaceframe, his team added side body panels made from a composite of hemp matting impregnated with a resin based on rapeseed oil. The Cornwall-based boatbuilder Ecocats provided the main body panels, made from a resin based on cashew nut shell oil.
Fuelled with a blend of 15 per cent unleaded petrol with 85 per cent bioethanol, the Eco One car has a higher power-to-weight ratio than a Ferrari Enzo, can do 0-60mph in four seconds, and has a maximum speed of about 150mph.
Wood’s goal was to prove that cars built from, and fuelled with, plant-based products need not be slow and lumbering. ‘My goal is to make a race car that’s 95 per cent biodegradable or recyclable,’ he said.
While the Eco One is a research project, sacrificing looks for performance, its ideas have been taken up in a slicker way by Lotus. Now on show at the British International Motor Show’s green motoring pavilion is what looks like a standard model of the Elise — until you look closer.
Instead of the usual leather-clad interior the seats, door panels and gear stick are swathed in tweedy-looking wool and the carpets are made from sisal, a variety of hemp long used to make durable matting.
Other materials are also derived from nature. The body panels, like those of Eco One, are a composite reinforced by hemp, rather than glass fibre. ‘That was a great way of reducing the carbon footprint of the car, because the hemp is grown locally, which cuts down on transportation and, of course, hemp fixes CO2 as it grows,’ said Lee Preston, environmental manager at Group Lotus. ‘And it’s also lighter than glass fibre.’
‘We achieved a 10-20 per cent reduction in gas usage,’ said Preston. ‘That’s likely to be the biggest thing we’ve learned from this project to be carried over into production, although we’re also very encouraged by the results we had from using hemp.’
Henry Ford’s first cars used hemp in much the same way as these engineers, and Rudolf Diesel invented his engine to run on hempseed fuel. After almos ta century, auto makers are finally returning to their hemp roots.
