How do you make wind turbines more efficient?

07 January 2020

WIND_TURBINE

Close-up of the top of a wind turbine.

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Question

Are there ways to make wind turbines more efficient?

Answer

Tech journalist Tim Revell tackled this question...

Tim - The simple answer is: yes. So wind turbines have become a lot more efficient, and the best thing you can do to make a wind turbine more efficient is make it bigger. And that comes in two flavours. One of them is making the blades bigger, the bits that rotate - normally there are three of them - and the larger they are, the wider an area they cover, and so the more wind that they can catch and then rotate. And that means the turbine can produce more power in total. The second thing you can do is make the whole wind turbine taller. It tends to be windier higher up, and the wind tends to be more consistent higher up. So the taller your wind turbine, that tends to mean that it can reach its potential energy more often. Which is a big deal with wind because it can be a bit intermittent.

Chris - People were talking about also using vertical blades? So rather than these things that look like a big fan that you'd blow air around a room with, actually having vertically oriented veins, as it were?

Tim - Yeah.

Chris - Is that better?

Tim - It depends. It's not really been proven yet which design is the best. There are these ones that are vertical and spin round, but they seem to have gone out of favour. The ones that tend to be more popular are the ones that are three blades that rotate a bit like a fan. But I think they are really incredible now. So the world's largest wind turbine is called the Haliade-X, and it is just extraordinarily large. So its blades are 107 metres long; that is longer than a football pitch, it's one and a half times the length of a jumbo jet, each one of its blades. In total the thing is about five times the height of Nelson's column, two and a half times the statue of Liberty, or if you built it in London it would be London's third largest building. That's just one wind turbine. And to give you a flavour of how much power that would produce, that's about 16,000 European homes that it could produce power for continuously.

Chris - And the noise pollution?

Tim - Well these are for in the sea. So you would have these in the middle of the ocean and then... yes, so if you were nearby you might hear it, but it's not going to bother you in your home.

Chris - One constraint that was raised to me, which I must admit... and perhaps you could speak about this as well, Ella, from an environmental point of view - everyone said these are fantastic things. They don't have a very big ground footprint. You can remove them and you don't ever know they were there, not like a nuclear power station where it's going to be there for hundreds of years. Problem is, those blades are all made of fibreglass. And therefore there's an enormous recycling cost built into that, because you've got something that's made of carbon-based product. You've got to ship the thing on and off of the turbine. You've got to then recycle it into something, but there is no facility to recycle these things like there's no facility to recycle fibreglass boats, so they're all going in landfill. Which kind of defeats the object, doesn't it?

Ella - I mean, yeah. In a lot of construction, or lots of renewable electricity generation methods, there is this problem. Because often you're non-renewable materials to produce something that will produce energy. But I guess if you consider the entire life cycle of a product, the amount of electricity or energy it produces is important to consider in the context of the materials that go into it.

Chris - Hannah?

Hannah - I didn't think ever about recycling a wind turbine. How long do they last for?

Chris - Well the boats are a good guide, because boats are about 50 years and then the glass tends to begin to de-laminate, where the layers begin to separate because you get water permeating in there. And also the sunlight falling on the polymer begins to degrade it. And it's the same with the blades. There is one factory I'm aware of in Germany that turn it into concrete. So they ship the blades to the factory, grind them up, and because the stuff just burns in the furnace, it actually contributes as a fuel to the furnace. And the glass is just silica, so that actually is what concrete or cement contains anyway, so it's just an additive in the cement. So it's quite a nice way of doing it. But you've got this enormous carbon footprint of shifting the thing that you've had up there generating a carbon neutral energy source, now contributing a lot of carbon in taking it to and from the wind turbine and then trying to recycle it, or even burying it. So that's an issue.

Jess - Can we think about more how we can fix these things and patch them up rather than completely getting rid of them and, you know, they go out of fashion and then we make a new wind turbine with a different design, potentially vertical; is there not a way that we try and resuscitate them?

Tim - I think that's something that will happen in the future. But at the moment we're seeing wind turbines going from almost nothing, windmills like the old style, to being these huge mega-structures. And at the moment the focus has been: how can we actually make them power homes in a consistent way. The next job will be: how can we make them a bit more environmentally friendly, in terms of the actual materials that are used. But even the materials that are used have changed a lot in the last 10 years. A large component as well as the fibreglass is also balsa wood. Balsa wood is one of the best things you can put in in a wind turbine.

Chris - And bamboo, they're using.

Tim - And bamboo, yeah, because wood is naturally flexible, so it's got that movement in it so that it doesn't just snap off when the wind blows. And then you've got... you know, you can't just glue a blade back onto half of a wind turbine. But in the future we may find ways to make them last, you know, after 50 years we give them a coat of something and then they lost another 50 years.

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