The Economics of Renewable Energy - Economic Affairs Committee Contents

Memorandum by Rear Admiral Robin Hogg and Professor Leslie Bradbury


  This submission deals specifically with "Issue 6" in the Select Committee's call for evidence. In Devon generally, and in the South Hams in particular, planning applications for Wind Farms have caused widespread concern, both locally by those living in the affected areas, and more widely by all those concerned with the peace, tranquillity and beauty of the largely unspoilt countryside. Whilst there is general support for the use of renewable energy, the trade-off between the effectiveness of Wind Farms on land and their effect on the countryside has resulted in much misunderstanding and cynicism in the public mind.

  It was for this reason that I commissioned the attached study by an aerodynamics consultant, Professor Leslie Bradbury, to examine the overall effectiveness of two typical Sites currently being applied for in the South Hams: one at the New Town of Sherford and one close to a remote rural community near Kingsbridge. His brief was to provide a balanced overview of the contribution made by Wind Farms to national power generation. This was to enable us to make a coherent cost-benefit analysis of the likely utility of these proposed Wind Farm Sites, set against their undoubted damage to the landscape and the wide enjoyment of it by all those who live in or visit the area. His conclusions have nation-wide relevance.


  I attach Professor Bradbury's report as a contribution to the debate but several key factors emerge that would, I hope, inform and influence their Lordship's discussions:

    —  Wind Turbines are inherently low energy sources and intermittent generators of electricity. Unless they are very large; typically with rotor diameters in excess of 90 metres demanding overall heights of around 120 metres and are sited in areas where there is sufficient predicted wind, they will not be effective. These sites tend to be in elevated areas and, by definition, highly intrusive to the landscape.

    —  For a wind turbine to be viable it needs to be erected in a position where there will be a "guaranteed average minimum wind speed of a 7.5 metres/second or above". It follows that any application to erect a Wind Farm that cannot guarantee such average Wind Speeds should not be considered. Such a limitation should form part of Planning Law.

    —  The technology and economics of wind power dictate that Wind Farms of less than 10 Turbines are not cost-effective. Small groups of turbines make little practical or economic sense unless forming part of a coherent industrial or business enterprise.

    —  Wind Farms make quite unreasonable demands on the environment in terms of land usage, typically requiring 1,000 times the land area of a single fossil fuel generation plant of the same generating capacity.

    —  Major cost-drivers tend to be: gaining access to the National Grid, the need for numerous turbines of very large size to make the investment viable and the lack of sensible Planning Guidance in PPS 22 and its extension.

    —  All investment in renewable energy involves "Trade-Offs" of one sort or another, whether it is for the application of Nuclear, Hydro-Electric, Wave or Wind power. Electricity generation using wind power is the only one of these technologies that cannot, by definition, contribute to Base Load, relying as it does on an unpredictable and unreliable source of energy. Any wind energy contribution must, therefore, be judged more critically for its effects on the environment when proposals to construct wind farms on land come forward.

  In submitting this short technical appraisal for your Lordships consideration we would strongly argue that an absolute minimum technical and planning requirement should be imposed on all applications to erect wind farms in England and Wales and that these limitations should form part of future Planning Law.

  This minimum technical requirement should be:

    —  Any proposed Wind Farm site on land should have an average wind speed of at least 7. 5 metres per second.

    —  No Wind Farm application should be considered involving less than 10 turbines.

    —  As a general rule, no Wind Turbine should be allowed within two kilometres of an habitable building unless linked to a coherent industrial or business enterprise.

    —  Bearing in mind Wind Farms excessive demand for land usage, the intermittent nature of the power generated and the unavoidable impact on the landscape, all future planning applications should be forced to give greater weight to environmental considerations.



  This note deals primarily with issue 6 in the Committee's Call for Evidence document.

How do the external costs of renewable generation of electricity—such as concerns in many affected rural areas that wind farms and extra pylons spoil areas of natural beauty—compare with those of fossil fuels and nuclear power? How should these be measured and compared? Is the planning system striking the right balance between all the different considerations?

  The present scheme whereby landowners can approach power companies to install wind turbines on their land is creating anarchy in the development of wind power in rural areas and, for that matter, elsewhere. It is resulting in large numbers of planning application disputes which are causing aggravation and costs to rural communities and, at the same time, encourages applications that would, in any case, make a negligible contribution to the nation's "renewables" power targets. The origin of this problem is vagueness in planning guidelines (like Planning Policy Statement 22 and its extension) and the fact that the Renewables Obligation Certificates make it attractive for power companies to install even relatively small numbers of turbines on sites that from a technical standpoint are not suitable in terms of the wind characteristics. In the long term, this could add significantly to the cost (as much as £10 billion) and the number of turbines (up to 50% more) necessary to meet the "renewables" targets. This problem is discussed in this submission and it is suggested that the planning guidelines and the overall planning process need modification to avoid these problems.

  Some comments will be made about the relative environmental impact of fossil and nuclear power stations compared with wind turbines and it will be argued that the planning system is not striking the right balance at all and that more precise criteria need to be met before planning applications should even be considered.


    —  Electrical power production in the UK in 2006 was 44,000 megawatts.

    —  A typical coal or gas power station has a rated output of around 1,000 megawatts.

    —  The submission mainly uses a 90-metre diameter wind turbine that has a so-called rated output of 2 megawatts as an example of a design that is likely to be most common for on-shore developments in the future. These stand about 120 to 140 metres from base to rotor tip. In the context of wind turbines, "rated" output does not mean deliverable power as it does with a conventional power station. Deliverable power is about a third of this and is a function of the hub mean wind speed as will be shown below.

    —  The area occupied by a 2 megawatt rated turbine is taken to be 0.16 square kilometres (ie a square of 0.4 x 0.4 kilometres).

    —  The cost of installing wind turbines is taken to be £1 million per rated megawatt for wind farm installations (say, 10 turbines or more) and £1.25 million for installations of one or two turbines.


  It is important to put numbers to our argument and so to set the scene, figure 1 contains calculations of the output of three wind turbines over a range of mean wind speeds from 5 to 10 metres per second. They are based on commercial designs. The first is a 52 metre diameter rotor that has a so-called rated output of 850 kilowatts. This unit is rather typical of the early units on wind farms in Cornwall and elsewhere. The actual power output from these turbines is very low at around several hundred kilowatts and they have made a negligible contribution to the "renewables" target and so should not be considered in any future planning applications. The other two turbines are more typical of recent designs with rotor diameters of 90 metres and 126 metres giving rated outputs of 2 megawatts and 5 megawatts respectively. The larger is a massive structure and probably suited only to off-shore developments. Thus, we are going to use the 90 metre 2 megawatts design in our submission as it will almost certainly be typical of the bulk of the on-shore units to be installed in the future around the UK.


  If we take 20% of the UK's electricity output for 2006 as an ambitious and long term guide target for wind power (ie 8,800 megawatts) then table 1 shows the impact of mean speed on (i) the number of turbines necessary to meet this target, (ii) the area they will occupy in square kilometres (iii) the overall cost and (iv) the cost per kilowatt-hour of the electricity produced. Also shown for the cost data is the influence of installing wind turbines in farms of, say, 10 or more as against installing them in small clusters of 1 to 3.

Table 1


Total power (megawatts)
Life of turbine (years)
Cost per turbine (10+ windfarm) (£M)
Cost per turbine (1 to 3 units) (£M)


Mean wind speed (metres/sec)
Mean power per turbine (kilowatts)
Numbers needed
Area covered (square kilometres)
Cost (£ billions) for high number wind farms (10+)
Cost (£ billions) for small number installations (1 to 3)
Pence per kilowatt- hour for high number wind farms (10+)
Pence per kilowatt-hour for small number installations (1 to 3)


  Because there are no quantitative planning guidelines on the wind speed of sites, many on-shore planning applications are made where the mean wind speed is 7 metres/second or less. As can be seen from the table, this sets a bad precedent because it will lead to far more turbines than are necessary if only sites with wind speeds greater than, say, 7.5 metres per second were considered as suitable. The consequences of this are that the wind power contribution to our overall power needs will be far more intrusive than it need be and at a far higher cost. As an illustration, if we take the extreme cases in the table of 6.5 metres per second and 8.5 metres per second, the extra costs are of the order of £10 billion for 50% more turbines. In addition, many of the rural sites being considered would contain only small numbers of turbines and this contributes further to the cost increment. From an examination of the wind map of the UK, there is no shortage of good sites both on-shore and off-shore but a more pro-active planning process is needed to ensure that they are used sensibly. Relying on the randomness of landowners striking contractual relationships with power companies is not the way to do it.


  With some particular exceptions referred to later, planning permission should not be considered for on-shore wind turbines unless the wind characteristics of the site meet some minimum standard. The suggestion is that this should be set at a minimum of 7.5 metres per second at the turbine hub height. In addition to this (also with some specific exceptions), planning permission for sites of less than, say, 10 or 20 turbines should not be considered. By virtue of their scale, these larger sites should therefore be reasonably remote from residential areas.

  Many do not appreciate that the requirement from "renewables" is not only that they produce "green" energy but they also have to produce electrical energy on an industrial scale. This is not going to be achieved by random small-scale developments but by properly sited large-scale wind farm developments. This is self-evident in off-shore developments but it applies equally well but—with more difficulty—to on-shore developments too. In this context, it should be noted that according to the latest British Wind Energy Association database, there are now a total of 2,032 wind turbines installed in the UK (both on-shore and off-shore). The rated output of these is given as 2,545 megawatts. If we assume a power factor of a third, this gives a real output of about 850 megawatts—still less than one conventional power station! Even this comparatively small contribution to the nation's power has caused an inordinate number of planning disputes and, unless the planning guidelines are modified, the whole development of wind power will become mired in a continuation of this process.


  One of the Catch-22 aspects of wind power is that areas like cliffs, hilltops and elevated terrain generally will have the most suitable wind characteristics and these are often areas of the greatest natural beauty and the most visible sites from afar. However, whilst the visual impact of wind turbines is a subjective issue, most would acknowledge that they are not too intrusive when viewed from a distance compared to, say, electricity pylons and other tall structures that litter the countryside. On the other hand, because of their great height and the dynamic effect of the rotors, their near-impact can be very invasive and can seriously detract from the attractiveness of, say, a rural village area.


  There are many industrial sites and estates on which small numbers of quite large turbines have been erected. These are mostly privately sponsored by the company or companies on these sites. Good examples of this are Avonmouth Docks (3 x 82 metre 2 megawatt turbines) and McQuains Oven Chips, Whittlesey (3 x 90 metre 3 megawatt turbines). Even when they are not particularly wind sites, these types of developments should not be discouraged because (a) they create no environmental or aesthetic problems, (b) they are invariably close to points of connection to the grid and so are comparatively less expensive than similar developments in rural areas and (c) they enhance the "green" credentials of the developers.


  If the above guidelines were incorporated formally into planning guidelines, it would at a stroke remove most of the contentious planning disputes such as characterise those proposals in rural areas and also those low-wind sites such as fenland areas. It would stop planning applications being made on small farm land plots adjacent to rural villages and it would concentrate efforts on those sites that offered a real contribution to our industrial power requirements as opposed to the almost token-like contribution that is a feature of many of the existing developments.


  The overall impact on the environment of different forms of power generation is a complex issue but we are here just concerned with the basic visual impact in terms of the land area occupied by the different power sources.

  The site of a typical 1,000 megawatt nuclear power station occupies around 0.5 to 0.7 square kilometres (123 to 173 acres) whereas a gas turbine power station with a similar output occupies 0.2 to 0.25 square kilometres (50 to 60 acres).

  In the case of nuclear power stations, they are invariably sited adjacent to the seashore because of the need for large amounts of cooling water. These sites can be selected so that their overall visual impact is very small. The visual imprint of gas turbine power stations is even smaller and, because cooling water is not required, they can be sited even quite close to urban developments without making a noticeable impact. A simple screen of trees will almost entirely disguise their presence.

  To generate 1,000 megawatts of wind power on shore using a 2-megawatt rated turbine will require between 1,250 and 1,500 turbines and they will occupy about 200 to 240 square kilometres (50,000 to 60,000 acres). Thus, there is about a 1,000:1 difference in the land usage and, unlike a fossil fuel or nuclear power station, this number of turbines would be visually very self-evident.

  It should be stressed that there are many hidden environmental effects from conventional power stations beyond their straightforward visual impact whereas the environmental influence of wind farms is almost entirely related to their visual impact. Nonetheless, as the basic sum shows, this is not trivial and it is yet one further factor making off-shore wind farms a more attractive option than on-shore ones.


  For background, Devon uses an average power of about 655 megawatts. Until recently, the county had no significant conventional power stations but, from late 2008, a new Centrica gas turbine power station just north of Plymouth is due to come on line giving an output of 878 megawatts.

  The South Hams area of Devon is a particularly attractive and rural part of the county. As yet, it is free of any wind farms but there are two proposals currently in place which, if approved, would set a very bad precedent for the future.

9.1  Sherford new town

  Sherford is a new town of 5,500 homes to be built east of Plymouth and to the eco-town specification. The plan includes provision for just two wind turbines rated at 2 megawatts that will stand in a parkland area within about 500 metres of the easternmost edge of the town. From base to tip, they would be about 120 metres in height. Based on the best wind speed data available, these two turbines would have a combined average power output of about 1.2 megawatts. No estimates of the overall power requirements of the town are to be found in the planning applications but a reasonable estimate is that it will lie in the range 6 to 8 megawatts. The inclusion of the turbines in the plan seems to be driven by concepts of local sustainability but, in the matter of electrical power, this is not sensibly achievable with wind turbines. The proposed town lies about one kilometre from the new gas turbine power station mentioned above.

9.2  East Allington, near Kingsbridge

  There is a hotly disputed proposal for three turbines to be erected on farmland in an area of attractive rolling countryside adjacent to three villages. It is an elevated and fairly windy site and the three proposed turbines would have a combined output of between 1.3 and 1.6 megawatts. Their base to tip height would be around 100 metres. This example would set an extremely bad precedent for the whole of South Devon. Once again, the power output would make an entirely negligible contribution to the county's power needs (let alone the country's) and yet it will impact on the ambience of the three villages in an entirely deleterious way.

  On page 8 of PPS22, there is the following paragraph:

    "(vi)  Small-scale projects can provide a limited but valuable contribution to overall outputs of renewable energy and to meeting energy needs both locally and nationally. Planning authorities should not therefore reject planning applications simply because the level of output is small".

  This is typical of the vagueness of the planning guidelines and it is leading to some frankly absurd planning applications that totally fail to address the real problem of providing industrial scales of power from "renewable" sources. The guidelines need to be rewritten to reflect that the "renewables" target represents a major engineering undertaking in which there is little place for ad hoc small-scale developments.

16 June 2008

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