Rustling trees give power for offices, chargers and streets

Watching a leaf fluttering in the wind has led to a new type of wind turbine that can be scaled from 9m giants that produce 5mW down to tiny miniaturised models that will fit under the eaves of an ordinary house and, linked together, can power a fridge, house lights or charge a mobile.

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Jérôme Michaud-Larivière had the idea of a tree – his Arbre à Vent – where each leaf was a windmill about one metre tall but not like traditional windmills.

Vertical-axis windmills are only usually seen on van roofs to turn an extractor fan but have many advantages, being silent, working with any direction wind, working in little wind and needing little space. Being vertical also means they can be styled as a biological mimic.

Based in Brittany – where he found his first financial backers – Mr Michaud-Larivière said he had been delighted to discover the engineering and electronic skills to turn his idea into a product. Access to ecological expertise had also allowed him to create the Aeroleafs using biodegradable materials such as hemp.

His Aeroleafs turn in the slightest breeze and a pair of Arbres à Vent were displayed for
delegates to the COP21 environmental summit in Paris last year – and brought reaction from businesses and governments from round the world.

Another was set up at the Roland Garros Grand Slam tennis championships this summer and recharged 5,400 mobile phones over the fortnight.

Trees cost €46,000 and go on sale from October and Mr Michaud-Larivière said companies and councils were his primary target as they needed 24-hour electricity to power office lights, garages, electric car chargers.

An Arbre à Vent can power a 100m2 office, light half a kilometre of street lamps or a car park and, as they work in wind as low as 2m/s (a light breeze), give power on about 300 days a year when conventional wind turbines turn just one day in four.

He said: “We have cities becoming smarter, with more new technologies and they all need 24-hour electricity. Our Aeroleafs produce it from where it was never before produced – in the centre of the city, where you could never have a giant wind turbine.

“This is a new source of energy.

“Each Aeroleaf can produce 100W at its best speed, which is winds of 16m/s and we limit them to turn at this speed. Higher speeds would need bigger, heavier units... that would work on fewer and fewer days.

“The Arbre à Vent has about 50 of them mathematically placed round the three branches to catch the best wind and least disturb other Aeroleafs. They cumulate the power produced and many Aeroleafs together can produce significant energy.

“Now we are miniaturising them to give a ‘bush,’ a ‘branch,’ a ‘rope,’ each with small Aeroleafs that give a little power in little wind that adds up to something significant. Imagine a factory roof covered in our ‘bushes,’ it could light the whole building!

“Motorway companies are looking at them to take advantage of the turbulence from passing vehicles to power roadside displays. Everywhere there is wind motion there is a chance to use that energy.

“Now if we take our bush and add little photovoltaic ‘petals’ we give even more energy. Eventually, our miniature models will sit under the eaves of a house and can supply continuous power.”

However, sales to the public are currently still a couple of years away.