Modern day turbine technology

How much electricity do wind farms actually produce?
07 June 2022

Interview with 

Karl Whittle, University of Liverpool


modern wind turbine


Julia - You can feel the wind absolutely whipping on the Northwest coast of England today. I'm currently hiking up a sand dune because when I get to the top of this, I should be able to see some turbines. Let's have a look. Oh my goodness, this is really steep. There they are. And it is really windy. It's pretty misty, but what I can see off in the distance is the Burbo Banks wind turbine offshore farm. From here, I can count 1, 2, 3, 4, 5. They just keep going. Let's get down off this windy hill, shall we? A little bit less windy down here maybe...

Julia - We've moved on from wind being used to produce food produce, like flour, and also draining water systems, to now powering our country. Big offshore wind farms like this one here in Crosby are doing just that. But just how much energy does a farm like this produce? Well, I think I should get off this windy beach and go into town to find out. I've come to the University of Liverpool to meet with Karl Whittle who is an engineer. He's going to tell me how they work.

Karl - They can be up to 150 in radius and they can now get up to 250 in diameter.

Julia - Is that in feet?

Karl - Metres.

Julia - 150 metres? Wow.

Karl - And it's because the larger the area, the more energy you can extract from the wind. You want to go bigger to extract more energy and more energy means you generate more electricity.

Julia - So, as these huge structures are turning round, how is that spinning being converted into energy?

Karl - The easiest way to think of it is like a dynamo on a bike. As you turn the wheel, it turns a generator. The way the generator works is exactly the same as a steam turbine. You have a magnetic coil and you have a magnet rotating around. Then, as it rotates around, it will generate AC current. A wind turbine then converts that to the usable energy that you want, whether it's AC or DC. Then, that gets transmitted to the grid or to wherever it is being used because some wind turbines can be on top of a roof that can then go straight to charging a battery, others can then go to the grid. The ones that you saw Crosby would go to the national grid.

Julia - You've got a diagram up here of the evolution of the wind turbine? It's like a Mercedes sign, a small one all the way up to a big, massive one.

Karl - Yeah, pretty much. That's what it is. They're just getting bigger. They're generating now, I think, the ones we can see at the moment, in the megawatt range of energy. If you have a wind farm of a couple of hundred or a couple of thousand of them, some of the big super ones, you're generating hundreds of megawatts, up to gigawatts, of electricity, which is equivalent to a nuclear reactor.

Julia - How many homes would that power?

Karl - It really does depend on the usage of the home, but one gigawatt would definitely cover Liverpool. And the newer ones will go even further, coming in land, in terms of how much electricity they can provide.

And what are these turbines currently made out of?

Karl - A range of materials aluminium steels for the stand and for the blades - that'll be made from composites now because we need to get the weight down because the heavier the turbine blades, the more energy it takes to turn them, it's an efficiency gain. We're just trying to get every little bit of efficiency; 10% here, 2% there begins to mount up over time. In some of the early designs, we couldn't really recycle everything. Now, we can recycle most things that come off. We are able to reuse the metals, we are able to reuse the composites if we wanted to. The carbon usage for wind is now to the point, after a number of years, maybe five to ten depending on the wind turbine design where you are now what would be defined as net negative carbon, in that you are generating electricity, compared to gas, that is no longer generating carbon.

Julia - Is there ever going to come a point where nearly all our energy in the UK can come from these structures?

Karl - It is conceivable, based on current usage of electricity, to have days whereby we've got more wind and solar than we have gas. The problem we have with wind is its intermittency. We're lucky where we are, geographically, and there's always wind. There's always wind somewhere. The problem is, some days the wind doesn't blow. So, if you were to look on bright sunny days a couple of weeks ago around here, we did have a bright sunny day with blue skies, but the wind was not strong that day. We relied more on solar than we relied on wind. We either need to increase our wind capacity, or the other way is to have increased energy storage, such as batteries or the use of hydrogen. Because one of the things that you sometimes find is that the wind is turning, but the wind turbines are not turning, because they're not needed for electricity provision on the grid scale. Or, the wind is really blowing and we have to turn the turbines off because we don't want to damage the wind turbines. We need to have other supporting things in place but it is conceivable, based on our current electrical needs, that we could have days in the next 10 years where we don't need gas, we can run on wind and solar together. Nuclear would always be there as a baseline, say, to provide a safe supply for electricity, but there will come a point when we will not need any gas at all in the day. As we move to net zero by 2050, and there are a lot more electric vehicles on the road, we then need to increase capacity even more to cover everybody wanting to charge their cars when they go home. That is a demand management issue.


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