Fifty shades of green

Written by: Eureka! | Published:
The most efficient EVs might surprise you - around 5 times the efficiency of an average petrol car. ...

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In this time of increasing demand for clean and renewable energy, companies are looking at any means necessary to produce extra energy that doesn’t rely on fossil fuels or other ‘dirty’ methods.

With the mass-adoption of electric models, the automotive market is going through the biggest sea-change since the internal combustion engine was introduced, replacing the horse and cart.

However, there are questions being asked about the green credentials of electric vehicles (EVs). Some claim that the emissions from the manufacture of EVs – specifically their batteries – are a lot higher than the manufacturing methods used to build traditional road vehicles.

The materials that make up the batteries of EVs include lithium, cobalt, manganese, nickel and graphite. These are not – as is frequently stated – ‘rare earth metals’, some are simply harder to find than others. Moreover, the mining of these materials is a political issue, as some are mined in countries with poor human rights records, which is simply unpalatable.

The real problem is how the electricity that powers the vehicles has been generated. Using coal-powered electricity, EVs do nothing to cut emissions, using natural gas electricity they’re like a top hybrid and using low carbon power they result in less than half the total emissions of the best combustion vehicle, manufacturing included.

The challenge

This month’s challenge is to come up with an idea for increasing the amount of electricity that powers an EV, or more specifically, smaller components, by purely renewable, free energy.

The obvious solution is solar panels but, given that the UK averages just four hours of sunlight per day – 1460 hours a year – why not see if you can come up with something that can power specific components all day long, all year round.

The idea we have in mind will, of course, be revealed in the November issue of Eureka! Until then, see what you can come up with. Submit your ideas by leaving a comment on the Coffee Time Challenge section of the Eureka! website or by emailing the editor:

The solution

The solution to last month’s Coffee Time Challenge comes from Falken Tyre’s parent company, Sumitomo Rubber Industries, and Professor Hiroshi Tani of Kansai University. Together they have developed a technology that could see tyres generate electricity whilst driving.

The Energy Harvester takes advantage of the build-up of static electricity, known as frictional charging, to produce power as the tyre turns.

Inside the Energy Harvester are two layers of rubber each covered in an electrode, along with a negatively charged film that interfaces with a positively charged film. When fixed to the inside of a conventional tyre carcass it generates electricity as the tyre deforms during rotation.

The engineers believe the Energy Harvester could lead to practical applications as a power source for sensors used in TPMS (Tyre Pressure Monitoring Systems) and other automotive devices without the need for batteries.

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Coffee Time Challenge is just a bit of fun, but it is based on a real engineering solution. If you send in your ideas by using the comment button below, we can add your solution as an alternative – perhaps something funny, practical, cheap or, of course, innovative.

The most efficient EVs might surprise you - around 5 times the efficiency of an average petrol car. To achieve this they use a lot of energy recovery already. Buy electricity from renewable sources and the carbon footprint is really very low. The next step will surely be car roofs and bonnets covered in solar cells which will add significant extra range to the average commute, and reduce the battery size and weight required- you probably shouldn't be so dismissive of solar!
Simon Canfer

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