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This post has been prompted by a discussion about wind power that I had recently. I have made clear that I am totally opposed to the construction of wind farms on ‘wild’ land. However, I am not opposed to wind turbines in principle. I think there is a place for a (relatively small) proportion of our energy supply to be met by wind energy. After making this point, it was recommended that I look at a number of articles which, it was claimed, ‘proved’ that wind power could never be economic.

I looked at these articles and the thing that I found most striking was that the authors looked at wind power in isolation rather than as part of a wider power generation system. They either were ignorant of or deliberately chose to ignore, critical factors that, in practice, meant their analyses are of no real value.

The energy supply system in a developed economy is a complex system. A complex system is one where there are a large and dynamically changing number of components with relationships between these components. Because of the dynamic nature of these systems, it is theoretically impossible to have complete knowledge of them so we can never produce a completely accurate mathematical model of their behaviour or other characteristics, such as whole life-cycle costs.

Complex systems generate enormous volumes of data. This data is rarely consistent and is frequently contradictory. Because of this, commentators with an axe to grind can usually cherry pick this data to support their own views. Hence, there are pro/anti nuclear articles which appear to be based on objective data analysis. When the alternative perspective is pointed out to those with one set of views, their reaction is often to ignore it or to rubbish the alternatives.

To provide a national energy supply, we cannot simply make decisions based on the cost of a generation technology – we must also consider at its availability (can it deliver power when needed) and its political and environmental risks. Availability is a key issue as continuity of supply is essential for the functioning of our society.

For example, we need to take into account the possibility of a nuclear accident, the possibility that political factors will cut off imported gas supplies, the possibility that weather conditions will mean that there is a widespread still weather so wind turbines don’t work and so on. There are lots of other issues and risks – some of which we DO NOT KNOW.

We can consider all of these other factors as RISKS – things that might happen which will lead to additional costs. A conventional economic approach tries to work out these costs and includes them in cost computations. However, if you try and do this in a large complex system such as energy supply, there are so many uncertainties that the resulting conclusions are completely unreliable.

In complex systems, there are things which are unknown and actually unknowable. Many classes of risk fall into this category. So, any assessment of the risk that e.g. Russia will cut off gas supplies to Western Europe so causing a huge spike in gas prices is no more than a guess. Therefore, because we cannot reliability assess risks or the consequences if these risks arise, we simply CANNOT accurately model the whole life-cycle costs of ANY power generation technology.

But we need to build a reliable power generation system so what do we do? We use two techniques that are fundamental to building any reliable system – redundancy and diversity. In power system terms, this means building more capacity than we need because we know we will have to cope with outages and using different technologies to generate electricity. This means that if there are problems that affect one kind of technology, then we don’t lose everything.

This need for diversity means that the Scottish Government policy that a very large proportion of our energy needs will be met from wind energy is highly risky and means that Scotland sometimes has to rely on imported energy. It also means that France’s reliance on nuclear energy is unwise, although less so because so much work has been done in understanding nuclear risk. It means that government energy subsidies for e.g. nuclear energy may make sense even although there seems to be ‘cheaper’ generation alternatives.

This post is already long enough and I don’t want to go into my opinions of what technologies we should be using or to go into more detail of complex systems issues. But there are two takeaways from this:

  1.  Most so-called economic analyses of power generation technologies are incomplete and only consider the price of these technologies. These should be an input to the decision making process but should never be the sole driver of that decision making.
  2. There is no such thing as an objective view of a complex system. We all can only have incomplete views that are biased by our existing knowledge and prejudices. We cannot ‘prove’ that people who argue for/against wind power, nuclear power, etc are right or wrong. They see the system in different ways and simply don’t listen to contrary arguments because these do not fit in with their world view.

It is perfectly valid to write articles, papers and blogs which discuss the costs of power generation technologies. But, some people who write such articles then go on to draw more general conclusions about these technologies in a broader power generation system e.g we should never build wind turbines. If these articles don’t acknowledge systemic uncertainties and risks and take these into account, then I advise you to treat their conclusions with the contempt that they deserve.

So what do I know?
I worked in the engineering of reliable, safety-critical systems (e.g. air traffic control systems) from 1990 to 2005. From about 2003 until I retired in 2014, I studied and analysed large scale, complex socio-technical systems. My father, as a consulting engineer, worked on every large and many small power stations built in Scotland between 1950 and 1975. We had lots of conversations about power stations as I was growing up and I think he hoped I would be a power engineer. To his disappointment, I followed the siren song of software engineering. Sadly, he didn’t live long enough to realise this was probably the right decision.

9 Responses to “Power generation is a complex system”

  1. Brian Sherwood Jones says:

    Good start.
    1. at an economic systems level, why do we think a renewables economy will work at the same tempo as an oil-based economy? The old windmills turned when the wind blew (and were sited to maximise that). Watermills could have some stored energy in weirs but I presume had seasonal variations. The energy storage problem is not amenable to a simple solution – stored energy is inherently dangerous. Big batteries sound like one of the stupider answers.
    2. Given that renewables are distributed, it seems unfortunate to have taken ex-CEGB engineers who understand concentrated generation and distribution and given them an ‘efficiency’ target at turbine level to work to. Small is beautiful would seem to be a better approach to a distributed resource.

  2. Alan Sloman says:


    You state: “It is perfectly valid to write articles, papers and blogs which discuss the costs of power generation technologies. But, some people who write such articles then go on to draw more general conclusions about these technologies in a broader power generation system e.g we should never build wind turbines. If these articles don’t acknowledge systemic uncertainties and risks and take these into account, then I advise you to treat their conclusions with the contempt that they deserve.”

    In the discussion we had on twitter I supplied links to http://euanmearns.com/

    If you read his blog it is quite clear that he does in fact acknowledge systemic uncertainties. Euan is an Associate Professor at your old University. I suggest you take another look at his work, as you have obviously only given it a cursory once-over.

    And feel free to comment on his excellent posts and let him know where he is going so very wrong.

    • admin says:


      I admit I only read the posts that you linked to rather than the blog as a whole so he may well discuss the systemic risks associated with the power generation somewhere. A search did not find anything but who knows what terminology is used.

      My point is that looking at technologies in isolation is the wrong thing to do. We need to consider the power generation system AS A WHOLE. Issues such as constraint payments may look daft when considered in isolation but may make sense in a broader systems context (I am not saying here that they do – I’ve never tried to do the analysis, but they may do).

      • Alan Sloman says:

        Perhaps you would prefer a more acknowledged expert in the field of energy infrastructure, Professor Dieter Helm CBE?

        I wrote a post two years ago on the UK’s electrical supply that included a House of Lords video of Dieter Helm giving evidence to the committee. It makes salutary watching and probably answers all your queries. He, surely, is independent enough for your taste.


        It’s the first video of two and you should slide to 11:39 am to see Dieter’s part in the proceedings.

  3. Alan Sloman says:

    A correction:

    Euan Mearns is an Honorary Research Fellow at The University of Aberdeen where he teaches occasional courses.


  4. I’m not an engineer, but it seems to me that while system resilience can be enhanced by diversifying system inputs, that only works if the inputs themselves are reliable, controllable and resilient. Seems to me that wind (and to a degree solar) fails these tests. If an input is unreliable and uncontrollable (as wind power is), then other parts of the system have to compensate, making the system as a whole more unstable (viz. problems balancing the supply grid to cope with fluctuations of wind power). Furthermore wind is very inefficient as it has a (very) low energy density. Contrast that with gas. High energy density, controllable and predictable. Issues over resilience can be resolved by having multiple gas power stations and adequate gas storage facilities (negating the supply interruption issue).

    Wind energy is also one of the most costly forms of energy production. One area of cost that seems rarely to be discussed is the huge area of land required for wind turbines to provide a modest amount of power. I did a post on my blog here: https://blogpackinglight.wordpress.com/2011/06/05/land-sacrifice/. From an economics perspective, it’s a poor use of scarce resources. IMO, whichever way you cut it, wind power is sub optimal and poor value for money. Not only that, it probably doesn’t save much, if any, on CO2 emissions over its life cycle. It’s ironic that the unreliability of wind power is leading to increasing use of backup diesel generators across the grid may actually be increasing net CO2 emissions.

    • admin says:

      Your first assumption is actually wrong. A general assumption in reliable systems engineering is that all components have a probability of failure.

      The economics of any generation source tends to be quite subjective (nuclear is a good example) but my point is that we may chose to pay more to reduce other risks. For wind, the Govt is paying more to reduce the political risk of failing to meet internationally agreed CO2 reduction targets and to avoid the political risk (massive budget and schedule overrun) of nuclear builds and the risk of public concerns over nuclear safety.

      • George Lindsay says:


        I fully agree with your first sentence but the issue around wind generation and grid stability is that wind speeds (and hence generation) ramp up and down quite significantly – often over a 24 hour period. This is significantly different to the unplanned outage of one generating unit and can seriously affect grid stability. Such instability has been experienced in Ireland and on continental Europe with almost catastrophic consequences Further and more recently South Australia experienced a catastrophic grid failure largely due to instability caused by wind generation. I would agree that there should be room for some (limited) amount of wind generation on the grid BUT we are now at a stage where the instablity potential is serious – even the NG admits this.

  5. I’m think you’ve made an implication about my first remark that isn’t there. By saying reliable, I didn’t mean infallible. I’m not assuming a zero chance of failure of any component, merely that it makes sense to have a system composed of components that are more reliable than one that is composed of components that are less reliable.

    The problem with wind is not so much that it is prone to a structural failure but that it is very prone to a failure to produce any electricity at all for significant periods of time when the wind doesn’t blow. At these times the rest of the system inputs has to make up the shortfall. The other problem with wind is that even when it does blow, it is not constant over extended periods of time leading to variable production of electricity which can cause problems balancing in the supply grid. Arguably, solar or even tidal power is better in this respect.

    I’m well aware of the subjectivity of the economics of power generation and have read quite a lot about it, prompted by Alan’s blog posts. However, the fact that judgements are involved doesn’t mean that my reading on the matter is of no value. It leads me to believe that wind is a very poor value for money, especially when we see the increasing use of diesel generators as backup.

    If you also take into account the vast area of land required to generate modest amounts of electricity from wind power, then it becomes an absurd proposition (solar has a similar problem BTW). It’s not surprising that the only places that wind farms are being built are on wild land and offshore where land costs are minimised.

    For all these reasons, I think wind power is a very poor option and a very costly one for the poor old consumer.

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