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Wind farm layouts

Wind farm layouts are pretty controversial. The bare fact is that putting turbines in the most lucrative positions which catch the most wind generally means putting them on top of hills. Which makes them visible for miles around.

There’s not really much that can be done about this conflict.

Besides, developers of wind farms don’t, as a general rule, actually buy the land they’re building on. Usually they rent it under contract from the landowner. And although the area of the wind farm is usually large, there’s usually a fair bit of spare ground around the turbines which can continue to be used for livestock or crops. In Scotland, we have laws protecting the right to access land; this means that if you want to go mountain biking at an operational wind farm the law is on your side (up to the point where you do any malicious or criminal damage etc obviously).

Once a contract has been drawn up with the landowner or landowners for a particular wind farm, it’s time to design a layout. This remains a challenging issue.

There are a number of criteria which are likely to restrict your options before the wind can be taken into account. These will include bird and wildlife surveys; land use and availability for roads; waterways and steep valleys which restrict access to heavy plant; planning restrictions on tip height; noise considerations; nearby residents; ground suitability; and local considerations such as archaeology, sites of scientific interest, and so on.

From there, the best practice is to use actual wind measurements to model how the wind flow changes across the site. Because you need at least a year’s worth of data from a met mast before you can really use the data (to cover all seasons), the reality of this part will vary substantially depending on how far into the project we are. If the project has two years’ of measurements at one or more masts on site, then great. Otherwise there are other sources of wind information we can use: bought data from a Met office measurement station; a virtual met mast built from a model; reanalysis data based on satellite measurements; extrapolation based on a combination of measurements. If the worst comes to the very worst the rule of thumb that “higher elevation = windier” would provide at least a guide.

Once you have an idea of the wind flow, you need to decide where to put the turbines. There are a number of things to take into consideration when doing this.

Each individual turbine removes a little of the energy from the wind it encounters, resulting in a slower wind speed for those turbines behind it. It also increases the turbulence, which further reduces the effectiveness of the turbines behind: it’s harder to extract energy from turbulent air. The combination of these is called the “wake” effects in the industry. To reduce the impact, it’s considered best practice to leave between 4 and 7 rotor diameters’ worth of gap between the turbines. Larger spacing is generally left in the predominant wind direction so that the overall wake effect is lower. (Offshore the spacing is larger, because wakes travel further offshore for reasons to do with atmospheric effects. Best practice will also vary from region to region based on the appropriate climate drivers.)

Trees and slopes will have several impacts on your positions. The top of a hill will be the windiest location, but steep slopes can provide huge challenges for accessing the turbines for construction or maintenance. Steep slopes also tilt the wind to an angle, and above 17° or so start to cause real problems for accurate wind flow or turbine performance modelling. Forestry increases turbulence directly above the forest, and can have other effects on the wind flow (increased change in wind speed with height, for instance, and boundary effects at the edge of the forest) which reduce the efficiency of the turbines.

Dwellings should generally be avoided as far as possible. I think the guideline in Scotland is 500m (note: there are experts on these constraints, and I’m not one), but a much larger buffer zone is wise. The issues of noise and shadow flicker are only relevant with regards to nearby homes. The danger of ice throw from blades or of blade throw is not thought to be a risk beyond tip height of the turbine (so if the turbine is 160m tall and you’re more than 500m away the risk to your property from these things is vanishingly small). To be honest I think the main driver here is the good will of the community. Big wind farms are generally built by bespoke developers, and there is much to be lost in appearing to trample over communities.

You want to maximise both the number of turbines and their output. Developers (or the banks who lend to them) take on the financial risk of a project when they sink their money into constructing the wind farm; they get nothing back until they start to produce electricity. If the costs of building and maintaining the wind farm turn out to be more than the wind farm can generate, the project is a failure. So the energy output is actually critical to project success.

Ultimately, then, from an industry perspective, the challenges of layouts are as follows:

  • Comply with all planning restrictions
  • Keep the local community on-side as far as possible
  • Space the turbines 5 by 3 rotor diameters, which for an 82m rotor diameter machine (about average for large wind farms at present) is 410m by 246m
  • Keep the turbines away from steep slopes, forestry, and dwellings as far as possible
  • Install as many turbines as you can to increase your maximum production
  • Put your turbines as high up as you can manage

I’ve often seen the accusation “poorly sited” levied at wind farms in newspaper letters. Reading between the lines, I suspect that this is because the writer objects to wind farms on hills where they can be seen, rather than that they know a secret way of establishing the best place to put wind farms that the industry hasn’t stumbled on yet.

On austerity

I think the people most impacted by the current government’s completely inexplicable austerity drive are the people who rely on state money, whether as benefits or because the state pays their wages. I am in the very fortunate position to be privately paid, and in a high-skill, high demand area.

Even so, I’ve found that the austerity measures are having an impact.

I guess the first thing I’ve noticed is that my money isn’t worth as much, and my time isn’t worth as much. Wage rises are very low, generally less than inflation; and the rate of interest you get on any money you can afford to save is actually laughable. (My “interest paying current account” was demoted to “current account” when it stopped paying interest, and I recently saw a poster advertising an actual ISA with 3% interest which only a few years ago would have been miserly for instant access savings.)

At the same time, the public discourse is highly demotivational and depressing. “Do more with less”. Services being cut at every turn. Tabloids turning on the unemployed, the sick, and the disabled, as though the tiny fraction of GDP which represents benefits for the genuinely needy is anything to do with the size of our defecit. On a personal level, individuals have to stretch their money to pay for their own higher education, their own retirement, childcare for any children, their day-to-day living expenses, the astronomical cost of housing… It’s depressing to feel like your time is not worth as much and at the same time to know that you have to pay for your past, present and future (and that of any dependants) out of a shrinking pool of income at a time of high inflation.

And of course by cutting benefits the government is telling me in no uncertain terms that if I fall sick or lose my job, I’m on my own. And I actually can’t save up for that possibility because I’m too busy saving for home repairs, pensions, student loans and you know, actual living expenses.

The thing is, if you’ve always had money you won’t see that. If you are in the fortunate position of having always had a little bit put by either by your parents or through some other means then you’ll never see cost as an ultimate problem. Similarly if you bought your house in the early days of the boom and sailed up the housing ladder on equity then you won’t appreciate how different it looks when you stretched yourself to the limit at the end of the boom to buy your house and watched its value fall through no fault of your own. The rich don’t see money as a problem, it’s always there when they need it. It’s more a way of keeping score.

Any household which covers its debts by letting its members starve and die is doing something wrong. That’s what this government’s austerity politics are doing, as disabled people are villified by their neighbours for the pittance we spare them. The government is letting us down; failing in its duty of care to its own citizens.

It sounds like socialism, and it is. Because how can it be bad for the resources of the many to be used to help those with nothing? You can only villify socialism if you genuinely believe we all have equal opportunity to be rich. And you can only believe that if you walk around with your eyes closed and your fingers in your ears.

(For context, I just read this. Alongside some other things I’ve read, the whole thing really worries me. I have worries about the independence debate, most notably regarding how little information seems to be available about what the former Great Britain might look like after independence, but this government would drive me to a YES vote on the grounds that at least Scotland might not have to face the worst. And if it’s impacting me, the picture of the squeezed middle, how much more must it be hitting the genuinely poor?)

Normal service will be resumed shortly…

I’m starting to get really worried about the wind industry. I think it’s an important industry, for several reasons:

  • It brings jobs to Scotland, even in a time of recession,
  • It allows for our dependence on imports for electricity supply to be reduced,
  • It reduces the carbon intensity of our energy,
  • It serves as a point of learning on the road to making real use of our renewable resources: solar, wave and tidal, and whatever new technology comes after.

What worries me is that the debate on wind energy, from the pro-wind side, is totally dominated by three voices: the economists/business leaders, the politicians and the green activists.

The way I see the world, politicians are there to tell us if something should be done; economists tell us if people will pay for it; and activists are there to lobby for a pre-existing set of ideas. When it comes to “can something be achieved”, that’s where you need the geeks: specifically the scientists and the engineers. And the scientists and engineers are very, very quiet on the issue of wind power.

Part of the reason for this is that wind energy for large-scale electricity is still very much in its infancy. Ten years ago, the procedure for installing a wind farm was completely unrecognisable compared to what happens today: masts were smaller, turbines were smaller and closer together, and the softer requirements like bird surveys and protection for peat lands weren’t as well established. Ten years in a career is a long time; but it’s hardly any time at all when you look at how quickly the onshore wind industry has grown. (Offshore wind has barely begun its journey yet, so I’m not talking about that.)

Within that huge rate of growth, large companies have grown from small groups of tinkering engineers, and somehow the managers, the politicians and the economists have become the dominant voices. And they say: protect our IP, don’t say anything which will bring the industry into disrepute, keep to the party line. It’s scientists who say, share data, do best practice and let people see it’s being done. But somehow the scientists and the engineers aren’t making the decisions in this industry. And where they’ve risen to the top, they seem to do so by falling in line with the industry position. Don’t question, don’t talk about any issues, don’t ever suggest there’s anything wrong. And so they become the business leaders, the economists, the politicians.

One result of this is that an industry which employs hundreds, perhaps thousands of highly-qualified engineers, and a fair few scientists too, doesn’t seem to have the geeks on their side.

I’m talking about this blog. The author of the blog is Colin R McInnes, a professor of engineering at the University of Strathclyde. As a citizen, he’s been writing to newspapers fairly often lately. His letters tend to be good engineering, as you’d expect, but they tend to come down on the anti-wind side.

He’s not correct. But, and this is important: IT IS NOT HIS FAULT THAT HE’S WRONG.

He’s an engineer. More than that, this guy researches into solar sails for a living. If you asked him about whether solar sails were worth investing public money in, presumably he’d say yes. This is frontier research: it can’t fund itself without huge subsidies. Yet this same man is essentially arguing that if offshore wind farms, a very new attempt at large-scale deployment of technology to an extremely challenging environment, can’t fund themselves commercially then they should be scrapped. So what’s the difference?

He doesn’t know that we’re here. The scientists and engineers who are tasked with building wind farms and actually making them work. He’s not in the industry, doesn’t go to conferences or meetings. He’s only engaging with the public discourse. Which is, as I stated earlier, dominated by politics, activists and the party line. He is operating in a complete vacuum of technically-literate information on wind farms.

We need to start talking in a language that the technical people can understand. That means demonstrating good practice and actually letting the numbers out there. How much are wind farms generating? Why are they being installed where they are? What are the measured capacity factors? How do we determine the layouts? What actions do we take to mitigate public concerns? How do we re-power or decommission a wind farm at the end of its life? Are we held to account if we breach our planning?

I don’t know if I can make this happen. This blog is a start, I suppose. Perhaps you can. The time for secrecy is ending; if anything I’m very concerned that we’re already too late. What might have been good for an individual company is threatening to doom an entire industry. And that industry matters.

As I said earlier, I’ve been reading the Geek Manifesto lately. This is the sort of thing you don’t read if you want a quiet life of rolling your eyes when people are wrong rather than gathering friends to overdose on homeopathic remedies outside a chemist.

It has come to my attention that one Mr Griff Rhys Jones has recently weighed in on the wind farm question. He has been quoted as claiming that wind farms are “green tokenism”, and being “randomly deposited” across the country. (Apparently this is from a column in the Radio Times, which is not online.)

Fresh from my perusal of the Geek Manifesto, it occurs to me that there are some parallels between this occurence and the British Chiropractic Association vs Simon Singh libel case. In the BCA case, Simon Singh had claimed Chiropracters made bogus claims; the BCA then sued for libel claiming damage to their reputation. In the case of Mr Rhys Jones, a celebrity has similarly made comments which are highly damaging to the reputation of an industry.

Only I can provide all sorts of evidence that wind farms are not “randomly distributed”, and that far from being “green tokenism” they actively contribute to our electricity networks saving on fossil fuels.

(I’ve not linked to much for the first statement about not being randomly distributed because to be honest it’s a bit of a blog post in itself and I don’t think anyone’s written it yet. Basically I need to demonstrate that there are financial incentives to build in the windiest places, that there are well established procedures in the industry for establishing windiness before construction, and that these procedures are generally followed. Some of the evidence may be commercially sensitive, but certainly there’s a solid case there.)

Has the reputation of the wind industry been libelled? Well, let’s be honest, Mr Rhys Jones is no more guilty of that than dozens of journalists, editors and commentors in print and even more random people online. But maybe they are all guilty of libel. Because I see far more accusations of bad practice from random people than I’ve seen any evidence of it. I’m not saying that the industry as a whole should start suing for libel when critics make rash statements which aren’t backed up by even a modicum of evidence. Neither am I saying that the wind industry is perfect. But no industry is perfect.

I do wish that celebrities, whose opinions are magnified in today’s culture, would try to remember that if it isn’t backed up by evidence it’s only an opinion.

“The Geek Manifesto” is a book by Mark Henderson which has been making quite a splash with a few science-minded people I know: I think I’ve had it recommended to me about four times by different people. So I bought it for my kindle and I’m now about half way through.

Because I’ve been following a lot of science people on twitter for a while, a lot of the issues raised by the book aren’t new to me. I followed the sacking of David Nutt for commenting on his scientific findings on drugs, I followed the libel reform case between Simon Singh and the BCA, and I also saw the birth of the Science is Vital campaign as a response to the 2010 Spending Review. These issues, and other similar ones are covered in the manifesto. I’m sure there’ll be others as I work my way through the book.

As a scientist, these issues do matter to me. I want decisions to be based on evidence, and I want politicians to try to compile high-quality evidence where it’s needed. It is true that it is easier in general to find examples of policy-driven evidence than evidence-driven policy; for instance, the War in Iraq was not justified by the evidence available at the time.

If there was evidence to show that wind farms don’t work — that they don’t produce power that can be used, that they fail to reduce CO2 emissions, or that they are ultimately more polluting than they save — I would want to know about it. I would want to say to my colleagues, look, it’s not working, let’s find another way, some other technology. I don’t want to bet my career on something that doesn’t work.

Of course, wind power may not be the best long-term solution to all our energy needs. That’s different, and fine by me. I’m not trying to build a panacea for all humanity’s ills, I just want to change the world a little bit to be a better world.

The truth is that the evidence /doesn’t/ say that. Wind farms produce more electricity than they use and they save enough in carbon to balance their construction costs in only a few months of their 20-year lifetime (also see here.

I wonder if part of the reason that the wind industry has failed to engage with its detractors is that most of our talking comes from the CEOs and lobbyists that are a crucial part of our industry, but who aren’t actually scientists or trained in assessing evidence objectively. That’s one reason why I set up this blog; I wanted someone to be presenting the balanced viewpoint that the energy debate demands.

Scientists are good at that, and we need to be here; we need to be heard.

There are some people who feel that those who are pro-wind-power must by definition be anti-nuclear. This is far from true in reality: both power sources include very different challenges but actually complement one another in some ways. Most engineers will tell you that we need a variety of generation sources to keep the power flowing on demand; running the grid with wind energy only would be a recipe for blackouts unless something really changed. Like hydro, nuclear is a generation method that doesn’t burn carbon and that is basically controllable on demand. Some environmentalists argue that in fact it is essential to include nuclear in the mix if you want to reduce carbon emissions in your electricity generation.

I don’t have any moral objections to nuclear; but I appreciate that it brings enormous challenges.

Still, it’s looking increasingly like nuclear power — or at least new nuclear power stations — will not be contributing much to the UK’s electricity generation in the near future. A summary of the situation:

There’s a lot there to suggest that the privatised electricity market in the UK simply doesn’t have the stomach for new nuclear generation.

Meanwhile, the UK’s existing nuclear facilities are aging; Germany intends to stop using nuclear at all and Japan has hardly started back up after the tsunami over a year ago.

Locally and globally the message is the same. Nuclear power — fission at least — may well have had its heyday.

Wind farms are pretty different to prior large-scale generating technology. A big way that they’re different is that we, as users, can’t choose ourselves how much fuel they need to provide us with the energy we want to use; we simply have to accept as much of the available wind energy as we can.

For some this is an insurmountable problem with the very technology. If the energy isn’t there on tap you might as well pack up and go home. To me that seems crazy. If someone offered you a £20 voucher towards your weekly shop, you wouldn’t toss it in the bin on the grounds that it wouldn’t buy your whole week’s food, you’d use it and make up the rest other ways.

Because of this intermittency problem, jobs like mine became available for the wind industry. Across the globe, whereever there are wind farms of any size, someone has to sit down with a computer and some wind measurements and try to assess what sort of production levels we can expect from them. In the early days, this was done based on some comparatively short measurement masts, using methods that were simplistic. Now, it’s a much better defined methodology, with larger masts, new technologies, and its own modelling tools to provide more accurate predictions of how the wind will vary in time and space.

The same sort of analysis techniques are used by the Energy Traders, who sell the generated energy under the system of the UK electricity market. Similarly, analysis of operational wind farms really benefits from that sort of detailed knowledge of the wind because it’s still key to understanding how far the wind farm is performing as expected.

So there are lots of benefits to the wind industry from this sort of work then. (Might be worth mentioning that these sorts of jobs are high skill, high demand and generally filled by people who live and work in the country in question.)

Even the most strident wind power advocate, though, doesn’t foresee a time when 100% of an electrical grid’s supply comes from wind power; not unless there’s a major leap forward in electricity storage. It is likely that other technologies like wave and tidal will start to mature to large-scale deployment.

When they do, those renewable resources will also need their resource assessed. And very similar techniques will be involved: make some measurements, assess their quality and representativeness, model where you have no measurements, and then feed through information about your machine and its output.

The national grid that was originally conceived to carry electricity from large-scale power plants to every home, factory and office was an astounding feat of engineering. However it was designed to match the supply to demand. The requirements of matching a variable supply with a variable demand are relatively new. Because wind power is the first renewable technology to get a substantial penetration into the generation market, the grid is learning to be more flexible. As we begin to use other renewable technologies — and we will — those lessons will transfer and we’ll have a system that can cope with the demands we ask of it.

Wind energy doesn’t have to be 100% of the answer to be a very important part of today’s and tomorrow’s technology mix.