First published on the Cleantech Investor website, December 2011. Copyright Cleantech Investor Ltd. 2011
Elisabeth Jeffries comments on innovation in energy harvesting
Many of us would love to see the back of batteries, at least in consumer products. They can be a nuisance; once they go flat, you have to remember to buy a pack on your next shopping trip. Then there are those awkward moments your new partner can’t get through because you’ve forgotten to recharge your mobile. Not to mention the waste! You have to remember to take them back to the supermarket or there’s a good chance they’ll end up in the bin. Useful though batteries may once have been, maybe they’re out of date. If we can get rid of wires, we really ought to be able to abolish batteries.
Life without batteries is certainly a dream cherished by many scientists all over the world. One thing known since the nineteenth century is that electricity can be generated from movement – vibrations from a machine or someone walking, say. This can be used for energy harvesting. There are quite a few ways of harvesting energy, one of which relies on stuff known as piezoelectric materials, found in some ceramics and crystals. The noise produced by the moving structure causes the piezoelectric materials to change shape, which in turn results in an electrical signal. It’s been shown to work, and researchers at MIT in the US have created electricity from a device fitted into shoes.
Rob Dorey, Professor of Nanomaterials at Cranfield University in the UK, has also been experimenting with these materials. Piezoelectric energy harvesting – collecting energy from vibrations –“is a great way of powering small or remote sensors that would otherwise need batteries,” he states. These days, sensors are found in all kinds of places, from road vehicles to outdoor lighting, sending out signals that can help cut energy use. They could be put on offshore wind turbines to send out intelligence to maintenance teams. But no-one will go out to sea just to replace a battery, so that’s where Dorey believes his work could make a difference. The sensor keeps on harvesting energy and transmitting the data back wirelessly. “I saw a real opportunity to use the technology in the area of energy and the environment,” he says. Much of the work focuses on using nanotechnology so that the piezoelectric material and energy harvesting device could be manufactured in a much more energy efficient way, avoiding very high temperatures.
Remote and small sensors are a relatively minor application though, because the amount of power they could harvest in these situations would be quite small. Dorey thinks combined heat and power holds much bigger potential and is currently working on EU project with the aim of generating 20kW. “A basic prototype/demonstrator should be up and running in the next year once IP is fully protected. We then have the flexibility to talk to companies or spin out,” he states.
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