Artificial Trees, Real Energy

Take a look at this thing. It may look like an art installation of some kind, but it’s much more than that. This is a Wind Tree, made by a French startup company called New Wind, and it may hopefully be a great way to generate energy in urban environments.

Each of those “leaves” is a small turbine, trademarked as an Aeroleaf, and is capable of generating 64 watts at peak output. This gives a typical 9.2 m tall Wind Tree with 54 Aeroleaves (Aeroleafs?) a power output of over 3.5 kilowatts. I say typical, because the modular nature of this device gives some freedom for customisation, meaning the number of turbines can vary depending on your needs.

For homes in windy areas, just one Wind Tree would provide a significant amount of energy for a home. The average home in the US uses about 10800 kilowatt hours (kWh) of electricity per year. Operating at only a third of its maximum efficiency, a single Wind Tree will account for nearly 95% of that.

Thanks to the small Aeroleaf design is that the Wind Tree can make use of lower speed winds for power generation – just 2 m/s, as opposed to the 4 m/s required for more traditional wind turbines. Another benefit of these compact turbines is that an Aeroleaf is sensitive to various types of wind. Windmills operate effectively with laminar airflow – wind which comes predominantly from one direction and maintains a constant speed. This is ideal for offshore setups like those in Scotland and the Netherlands, but not so good everywhere. Because of more complex urban landscapes, city wind can be turbulent and gusty. Thankfully, turbulent airflow works just fine to power a Wind Tree.

The guy in this video clip, by the way, is Jérôme Michaud-Larivière, CEO and mastermind of New Wind.

The intention behind the Wind Tree is to provide a safe and aesthetically pleasing way to generate wind power in places where the usual kind of windmill is inappropriate. Where regular wind turbines may be inappropriate in a city, Wind Trees may be easily included on university campuses, industrial parks, outside office buildings and on rooftops to provide a convenient way to generate power.

As it happens, a typical large office building uses around 20 kilowatt hours of energy – so on a windy day, just 6 Wind Trees would yield enough energy to actually make money by selling surplus energy back to the central power grid. Of course, this doesn’t count energy storage either. Renewable energy sources like wind operate continually even when their energy is not in use, and the Wind Tree is no exception. A storage battery saves generated power, which is then converted to AC at standard voltage when needed.

Small, distributed forms of energy generation like this may ultimately be a much more effective way to generate power, particularly with the increasing energy demands of a large city. For example, based on information from a few years ago, London has approximately 680 million m² of commercial property, with around 110 million m² of that being office buildings. Taking a typical office building to occupy around 1400 m², this gives over 78500 office blocks in London. If only half of these offices installed and maintained just one Wind Tree, it would provide up to 137.4 megawatts of power. In the same region as the output of a typical UK power station. 1.1 million Wind Trees would equal the output of the ominously named Drax Power Station, the UK’s largest.

Currently, a lot of  details appear to still be concepts and plans. Future concepts include turbines shaped like flowers, apparently with solar panels in the petals, or with different Aeroleaf colours. I quite like the idea of pink ones to look like sakura petals, myself.

Previous reports have suggested that New Wind intend to start production of these lovely devices sometime this year, with the cost of a Wind Tree expected to be in the same price range as a family car – an estimated €29,500. Unfortunately, their website doesn’t currently offer details. They gave the option near the end of last year, of preordering Wind Trees for the cost of around $1000 US each, though unfortunately their store website appears to be down as I write this.

All the same, I hope they’re successful. I’d love to see these around big cities. As well as giving some visual interest to city streets, it would be deeply comforting to know that cities were generating power this way.


About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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5 Responses to Artificial Trees, Real Energy

  1. Mary P says:

    Realistically, a lot of these things are unsuccessful because of lack of exposure and general apathy (often disguised as cynicism). I might well add a small turbine to fill in gaps in the winter but I have yet to see a small one suitable for a high-wind site.

  2. Ed Davies says:

    PS: I did see a brief item (might have been on Robert Llewellyn’s Full Charged YouTube channel) about a company near Swindon who were developing a small vertical-axis turbine-based device for domestic-scale use which looked well engineered as far as one can tell from a few quick shots of the prototype. They were deliberately not saying a lot until they had good measurements of actual performance, they were just starting testing at a small number of sites, because the market had been so badly harmed by these “urban” toys. That’s a respectable approach and I’ll be interesting to see how it comes out.

  3. Ed Davies says:

    Call me a cynical old git if you like but there’s a long history of these sorts of things, not entirely filled with success stories. Until we see them actually installed and producing independently documented amounts of energy it’d be more polite to just ignore them.

    • Invader Xan says:

      Realistically, a lot of these things are unsuccessful because of lack of exposure and general apathy (often disguised as cynicism). If everyone just ignores them, then quite obviously they won’t be installed, and they’re not going to succeed. Given the immediate action required to prevent catastrophic climate change, it makes more sense to promote them.

      • Ed Davies says:

        No, these things are unsuccessful because of the laws of physics. There simply isn’t enough energy available in the small cross-sectional areas they have from the turbulent and relatively low-speed winds in urban areas. ½Aρv³ × Betz limit for small v. Times another factor smaller than one because these things aren’t very efficient anyway (typically about 0.5 for a decent horizontal axis turbine; probably quite a lot less for something like this). A lot of things of this sort (VAWTs of this size or somewhat larger) have been installed in southern England and have served only to bring renewable energy into disrepute. For some reason VAWTs attract the deluded/scammers (it’s often hard to tell which) in much the way that cold fusion or even perpetual motion does.

        I’m very committed to renewable energy – building a completely off-grid (apart from internet connection) house in the north of Scotland for the reasons you mention. My site is pretty much ideal for domestic scale wind (100m ASL brow of a hill overlooking the Moray Firth, clear of much in the way of trees or buildings around it) but still my main focus will be on solar (mix of thermal and PV). I might well add a small turbine to fill in gaps in the winter but I have yet to see a small one suitable for a high-wind site.

        If these people actually want to make a contribution then building something like this but aimed for the locations where there actually is some energy to be harvested might be a good plan.

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