# How many wind turbines would it take to power the UK?

One of the rare pleasures in life is reading the latest piece of nonsense written by Christopher Booker in the Daily Telegraph. The fact that it is nonsense appears to be subject independent, but talk of wind turbines tends to ratchet things up a level. One of his favoured claims is that the UK will need to build 32,000 wind turbines to meet its 2020 EU renewable energy commitments.

The claim is groundless and not worth debunking, but let’s instead ask how many turbines it would take to power the UK. UK electricity demand was 381 TWh in 2010. How many turbines would it take to meet this? (Of course in practise this will never happen without massive breakthroughs in energy storage, but we’ll just imagine that supply and demand is met via new tech.)

As far as I know the average turbine capacity for new large wind farms is about 3 MW, so we can use this to get a lower bound on the number of turbines needed.

UK wind farm capacity factors have averaged just below 30% for the last few years, though there is a bit of variation each year. (Capacity factor is the figure such that average output = capacity * capacity factor.)

It’s difficult to project average capacity factor in to the future because offshore wind in will probably take up a higher proportion of wind capacity (which will increase CF), but onshore developments may need to move into less prime wind regions. I’ll just stick with 30%.

A little bit of arithmetic indicates we would need about 48,000 turbines to meet the UK’s annual electricity demand. The total installed capacity would work out at about 145 GW. (Note that UK electricity demand is never above 70 GW, so if storage methods aren’t sorted out windy days will see a lot of power wasted.)

Getting 100% from wind of course is not feasible. However electricity demand may need to double anyway in order to electrify transportation etc. So, 50,0000 may be a good ball park figure for getting 50% of electricity from wind in say 2040.

What about today? Renewable UK gives the following breakdown of UK wind farms:

Average wind turbine capacity is actually 1.9 MW. So, using this we would need about 75,000 turbines and not 50,000. Is my original choice of 3 MW too low then? Arguably the opposite. Public opposition to windfarms is growing rapidly. Offshore wind may end up dominating new build by the end of the decade, in which case average turbine capacity may go above 3 MW.

While only ballpark figures these are worth keeping in mind when you are reading the latest piece of nonsense about wind farms in the Mail or Telegraph, or for that matter The Guardian.

## 16 thoughts on “How many wind turbines would it take to power the UK?”

1. So, given that the land area of the UK is 243,600 km² we’d need a coverage of roughly one turbine every 5 km²; or, taking into account that urban land and Areas of Outstanding Natural Beauty are unlikely to be used, no more than every 2km apart. Discount all the bottoms and sides of valleys and (I guess) that would mean covering all hills, ridges and upland areas with turbines centred at about no more than 500m apart. Even if we see half the wind energy being collected off-shore that only pushes on-shore turbine density back up to 750m centres.

Somehow I just can’t see this happening in a densely populated country like the UK. Even in the lowest-population areas of the UK there are 30-40 people living in every square kilometre. Given the uproar already in rural areas (and I know; I’ve chaired a Parish Council meeting on this topic), I just can’t see it being politically acceptable for more than ~10% capacity being supplied by wind-with-storage.

• Thanks for the comment John

I’m writing a post at the minute about land use and renewables, (though for Japan, not the UK) so didn’t really want to touch on this subject. While I personally don’t think that wind farms are ugly, and would probably agree, in principal, that 30,000 turbines could be erected in the UK, it is important to recognise that opinions on this issue are subjective. It’s rather like trying to convince someone to like or dislike a particular piece of music. Efforts by some wind proponents to make it seem that thinking wind farms are ugly is somehow unethical is also just about as misguided as it gets.

I can’t see this number of windfarms being built unless they are built offshore. In that case there are major question marks over the economics. Nuclear power plants will probably remain cheaper for the foreseeable future. Limit onshore wind to say 10%, and you probably have to abandon any idea of powering the UK on renewables. Many Greens now seem to be in denial that their hopes of an all renewable future are hanging by a thread. There is still a strong economic argument for onshore over offshore wind. However there also seems to be a taboo around making that case. A couple of recent pieces by Caroline Lucas and Natalie Bennett of the Green Party both rather strangely said that onshore wind “was among the cheapest renewables” instead of saying it was the cheapest, and twice as cheap as offshore wind. My own feeling based on the way the opinion polls are going is that the majority of people will want no more onshore wind farms built quite soon, maybe by the middle of the decade. This is probably now a losing battle, and a cap on onshore wind farms now seems inevitable.

2. Steve Jones says:

John – David MacKay’s brief chapter on wind is a nice companion piece to this post, where he talks about land-area required for all the turbines. The windiest 10% of the UK apparently (if they were all onshore).

Robert – I bet the 1.9MW average is indeed artificially low. It’s dragged down by some 0.1MW corporate vanity turbines.

• Steve. Your point about “corporate vanity turbines” in this case is not true. I had a quick look at the Renewable UK stats (not sure where I got them) and there are less than 5 below 0.5 MW, and non of them could be called “corporate vanity turbines.”

• Steve Jones says:

Ha, well, perhaps “corporate vanity turbines” was slightly “sexed up” (smiley face), but I scrolled down the list and saw, Ford, BSkyB, East Midlands Airport, Sainsbury’s, Royal Mail etc. I obviously don’t know the full story behind each one.

I don’t know where you get 5 below 0.5MW from? You linked to the UKWED database – there are 100′s below 0.5MW.

…but anyway, we agree don’t we? If you ever did cover UK with wind turbines you’d do it with 3MW turbines in windy areas not BSkyB’s 0.1MW London offering. Despite the 1.9MW average, 3MW is a sound assumption.

• I think you’ve hit the main bone of contention there, Steve: “the windiest 10%”. The problem at the moment is that turbines are not being erected where they maximise wind availability and where they would best meet the country’s energy needs: that would require a carefully thought through, overall plan. No; they’re being erected haphazardly, wherever landowners want to make a fast buck, don’t live near their own sites, and where they’re prepared to shit on the locals.

In poor rural areas which depend on tourism, like where we are in Devon, the economy depends on the wild beauty of the landscape, which the locals now see being sacrificed for objects that bring absolutely no benefit for the local communities; communities who are scared that their tourist-based businesses in which they’ve invested heavily — dependent on horse-riding, camping, cycling, fishing, hiking and providing holiday accommodation — will be damaged. Wind turbines in the windiest places where the locals are compensated for the negative aspects — sure, they can cope with that; but what’s happening at the moment? …it’s seen as a knee-jerk, unplanned, unfair, mess.

I started out trying to defend turbines — I still believe in the part they can play in our need to reduce carbon emissions — but when you see locals in fear and in tears you come to realise that’s something is seriously wrong with the way the government is going about this. They need to engage their brains.

• Steve,

I don’t want to delete comments. However could you please just make your point clearly on the site instead of providing links. Also, this is broadening the discussion far too far beyond wind farms, which is the topic of the post.

And, who is “saying no to wind”? I certainly am not. David MacKay certainly is not. I don’t think John in his comments above is either. Reducing energy choices to yes/no seems to be mostly of interest to the dogmatic or people with financial interests in particular technologies.

• Steve Jones says:

Who’s saying no to wind? John is. He wrote several paragraphs on the subject.

• Steve

Can you please read what people actually say on these subjects? I can’t speak on John’s behalf, however “I still believe in the part they can play in our need to reduce carbon emissions” aren’t exactly the words of someone who says no to wind.

• No, Steve, I definitely don’t say ‘no’ to wind. I say turbines in the best places where the amount of energy harvested from the prevailing wind is maximised. So we get maximum bang for the buck. Then once we’ve put turbines up in the best places we slowly work backwards. If this philosophy had been followed from the start I reckon the current yield from the installed capacity would probably be at least 10% more than it is. Hence the need for a properly devised and agreed national plan.

3. Just a comment – talking “targets” – under the EU RES Directive – the UK negotiated down from 20/20/20 to 15/20/20 , ie 15% of ALL energy to come from Renewables by 2020. Of this, the UK is trying to achieve 10% of its electricity from renewables by 2020. The rest has to come from heat and transport – where we have hardly started…….

4. Robert – yes – apologies – you are correct. ……3.8% at 2011, up from 3.2% in 2010. Gonna be a struggle in seven years. …nukes stalling even further…and CCS not in sight….

5. PrKing says:

Contrary to your belief no “massive breakthroughs” in energy storage are needed for 100% renewable energy, but given that it would take decades to get there (e.g. as Germany is doing) then energy storage tech would have made massive improvements by the time it was needed.

Also, the need for it is usually massively exaggerated and you seem to have fallen for that fallacy.

> “Average wind turbine capacity is actually 1.9 MW”

That’s the trick David MacKay uses in his flawed and misleading energy book. He pretends that old turbines represent all that will ever be available. We already have 7MW turbines and 10MW+ are on the way.

You make a similar mistake with capacity factor. It’s much higher for modern offshore turbines especially. New floating turbines will increase it again.

The UK could become a net exporter of energy from just offshore wind. http://www.offshorevaluation.org/ – a much more reliable source than a blog picking numbers out of the air to prove a preconceived conclusion.