FIGURES

Power Output and Carbon Saving Figures
A Critical Analysis

(Please read 'LOW POWER, HIGH FARCE: YOUR ENERGY FUDGE THE FIGURES' below. This gives the more recent 'revisions' of YEL's figures.)

Your Energy's Moorsyde 'specification' sets out the same figures that are used in the Environmental Statement of the planning application (it should be noted that all Your Energy's figures are based on the Vestas NEG-Micon NM80 turbine which is no longer in production and which no longer has type approval):

'Moorsyde Wind Farm' Brochure - Page 5, 'Specification'.

Our Analysis

It should be noted immediately that these figures are absurdly precise, especially when taken in conjunction with the preceding 'up to': 91,060,200 kWh would normally be rounded to 90,000 MWh, for example. This suggests that the document was not drawn up by a competent engineer. However, in what follows we will take Your Energy's figures and work in their style for the sake of consistency.

1. The installed capacity of the Moorsyde wind turbine power station is stated to be 38.5 MW, so we can calculate the capacity factor implied in line one:

38.5 MW x 8760 (hours in a year) = 337,260 MWh (theoretical maximum energy output) x n (capacity factor) = 91,060 MWh.

Therefore, n = 91,060/337,260 = 0.27

This capacity factor is unreasonably high, and may be based on a naive interpretation of wind data which fails to take into account outage due to routine maintenance and mechanical failure.  Your Energy has, furthermore, publicly admitted in the Berwick Advertiser (21st October 2004) that the wind resource at Felkington is relatively low.  On the same day, at a Public exhibition at the Plough Inn, Charles Sandham, a Director of Your Energy at the time, described the wind resource as "disappointing".

In the DTI’s Digest of United Kingdom Energy Statistics 2004 (July 2004) [DUKES], Table 7.4¹, the achieved capacity factor for the UK’s installed onshore wind power is given as 24.1% (i.e. 0.241).

If we recalculate the likely energy output from the proposed 'Moorsyde' turbines we can see just what difference a more prudent estimate of capacity factor can make:

38.5 MW x 8760 x 0.241 = 81,280 MWh

The use of the qualifier 'Up to' may be thought by some to guard against this sort of criticism. However, in the context of an advertisement (which this brochure is) a reader may be misled by the misapplication of a 'ceiling' figure (this point is well-recognized in advertising; we need only think how careful advertisers of cars must be in stating fuel consumption figures).  On its own a 'ceiling' figure tells the reader very little, and it is only in conjunction with a probable figure that it takes on any significance.  This point with regard to the 'Up to' phrasing will be invoked several times below.

2. In line two of the table it is estimated that number of 'local homes supplied' is 'up to' 20,957.

There are two points to make here:

Firstly, that the phrase 'local homes supplied' is peculiarly vague and imprecise, and suggests to the reader that the energy from the turbines is being sent directly to these homes, which is not the case since these turbines will be connected to the national grid.
It is extremely difficult to determine where such power is eventually consumed, as noted in the DTI’s Wind Energy Fact Sheet 11.

"Electricity generation and consumption is a displacement system, i.e. for every bit used, the same amount must be supplied somewhere else.  There is no storage of electricity and no leakage. However, because the network is very large and complicated, it is not possible to determine exactly where electricity from any single generation source is finally used."²

Secondly, the figure for the number of homes, which Your Energy Ltd. says is based on figures from 'UK Digest of Energy Statistics' (presumably the DTI’s Digest of United Kingdom Energy Statistics), 1998, is somewhat low at 4,345 kWh per household per annum.  Even the wind developer’s own trade association, the British Wind Energy Association [BWEA], now recommends the figure of 4,700 kWh per annum.³   Your Energy Ltd can hardly be unaware of this figure: Mr Richard Mardon, Your Energy's latest MD, is (like his predecessors) a BWEA board member.

However, if we retain Your Energy’s own estimate of energy generated (91,060 MWh) but use the figure of 4,700 kWh for annual domestic consumption, we arrive at a somewhat different number of houses, namely 19,374 houses, as opposed to 20,957. Furthermore, if we downgrade the estimated energy generation in accordance with the DTI capacity factor of 0.241 we arrive at the figure of 17,409 homes.  This is a significantly smaller number.

3. In line three of the table Your Energy Ltd. estimate the carbon-dioxide savings as 'up to 78,225 tonnes'. We can therefore calculate the 'emissions factor' employed by Your Energy:

91,060 MWh x n (emissions factor) = 78,225 tonnes
Therefore, n (emissions factor) = 0.86 tonnes per MWh.

This appears to be an unreasonably high estimate.  0.86 tonnes per MWh is, it is true, an emissions factor recommended by the BWEA,⁴ and as explained by that organisation is typical of a coal-fired power station.  This can only mean that Your Energy Ltd. are calculating savings on the assumption that the conventional generation displaced by the UK’s turbines is only high emitting coal generation.  The BWEA endorses such a procedure, but, and this should be emphasized, the assumption is not valid and is not supported by governmental organisations.
In fact, it is notoriously uncertain as to what generation would be displaced by wind turbines.  The DTI’s Wind Energy Fact Sheet 14: Energy and Performance (DTI: Aug. 2001), p. 4, states, very wisely:

"[…] the emissions avoided when a wind farm operates depend on what type of power plant wind displaces and the operating emissions of that power plant. Reductions in emissions will be greatest if wind displaces coal, significantly less if it displaces gas or nuclear. The UK electricity market is extremely complex, particularly under the New Electricity Trading Arrangements (introduced March 2001), and it is not possible to make categorical statements on how wind changes the generation mix."⁵

This is incontrovertible, and consequently, it would be much more truthful and accurate when discussing annual CO2 emission savings for Your Energy Ltd. to use a grid average emissions figure, rather than the one typical for coal, and this is in fact the course recommended in the DTI’s Wind Energy Fact Sheet 14: Energy and Performance.
An up-to-date average can be found in DEFRA’s recent Guidelines for the Measurement and Reporting of Emissions by Direct Participants in the UK Emissions Trading Scheme (June 2003), Protocol A1 of which gives (p. 20) a figure of 0.43kg Co2 per kWh, i.e. 0.43 tonnes per MWh.
The use of a grid average is also the method recommended by the Carbon Trust website in a worked example showing how to calculate the emissions saved by a renewable energy project.  The emissions factor used is 0.43 tonnes per MWh:

Power generation⁶

CO2 emissions saving = total predicted electricity production from the renewable technology (kWh) x emission factor (kgCO2/kWh) x 0.001
Total predicted electricity production from renewable technology = 1000kW per unit x 10 units x number of hours of use (10 years x operating days (365 x utilisation rate (0.7) x 24).
Total predicted electricity generation from renewable technology = 613million kWh
Emissions saving (tonnes CO2) = renewable electricity generated (kWh) x emissions factor (kgCO2/kWh) x 0.001
Emissions saving (tonnes CO2) = 613million kWh x 0.43 (grid average) x 0.001
Total emissions saving = 0.3 million tonnes CO2

(NB: the multiplication by 0.001 serves only to turn kg of CO2 into tonnes.)

Further confirmation, if it is required, can be found in the fact that Ofgem recommend the use of a grid average figure of 0.43kg per kWh (i.e. 0.43 tonnes per MWh) when converting Renewable Obligation Certificates to Emissions Trading Scheme credits:

"[…] if individual suppliers choose, they can convert ROCs to credits measured in CO2 (carbon dioxide) equivalent, and use them in the Emissions Trading Scheme. For the purpose of the scheme, it will be assumed that electricity from renewable sources displaces fossil fuel generation at a fixed factor of 0.43 kg CO2 / kWh."⁷

In fact, because of inefficiencies in plant required to act in a backup role for wind, there are further doubts over even the 0.43 emissions factor recommended by DEFRA, DTI, Carbon Trust and Ofgem, and these arguments are ongoing in technical engineering circles.⁸

It may become necessary to re-evaluate Your Energy Ltd’s claims in the light of those debates in the future, but at present it is enough to say that Your Energy Ltd’s claims that the proposed Moorsyde wind turbine power station would save “up to 78,225 tonnes” of CO2 emissions is a significant exaggeration, and the evasive phrase “up to” does nothing to mitigate this.  A frank, honest, and straightforward usage here would be to provide a simple figure based on a generally accepted grid average emissions factor. The full significance of this point can be seen from application of the lower capacity factor argued for above.

81,280 MWh x 0.43 = 34,950 tonnes p.a.

This is a mere 45% of the tonnage claimed by Your Energy Ltd.

In addition, it is worth noting that no allowance is made in Your Energy Ltd’s calculation for emissions involved in the construction, installation, and servicing of the turbines. The exact quantities of these emissions have not, as far as we are aware, been calculated for modern industrial wind turbines, which are in excess of 100 metres in overall height, weigh between 222 and 238 tonnes,⁹ and require reinforced, high-density concrete foundations of around 400-500m3.  It should be noted, however, that the DTI’s Wind Energy Fact Sheet 14 (August 2001) admits the point in principle:

Wind farms do involve some emissions; these come from using conventional fuels during their construction and servicing. The life-cycle emissions take this into account.¹⁰

The DTI quote lifetime emissions calculations from ETSU-R-122, New and Renewable Energy: Prospects for the 21st Century: Supporting Analyses, totalling 9gm of CO2 per kWh, 0.06gm of SO2 per kWh, and 0.02 of NOx per kWh. These figures were calculated in relation to a much smaller generation of turbines, and may be conservative.
However, the application of these figures, though coming with a health warning, serves to point out that this is a relevant consideration and should be declared in relation to any claimed saving.

LOW POWER, HIGH FARCE:
YOUR ENERGY FUDGE THE FIGURES

"If you fudge an issue to get the result you want you will be exposing yourself to acute professional embarassment, and if people find you have fudged one issue they anticipate you have fudged everything." (Bill Richmond, then YEL MD. Berwick Advertiser, 11 November 2004).

'Moorsyde' Mk. II

Over a year after they submitted their planning application, Your Energy/Mistral started claiming that they would use powerful, 3 MW, offshore turbines on the 'Moorsyde' site. This gave a peak theoretical capacity of 42 MW (14 x 3 MW turbines) rather than the 38.5 MW (14 x 2.75 MW) that appeared in their planning application (the 2.75 MW turbine they had used in those figures was already out of production before they made their application). At the same time, they stated that the more powerful turbines would supply nearly 10% less power than stated in their original specification.

Very strange - an increase of 3.5 MW and the power output goes down by 10%!

Using their new figures, it appeared that the capacity factor of the proposal had mysteriously shrunk from 27% to nearly 22%. The wind industry likes to claim that appropriately sited wind turbines have a capacity factor of at least 30%. A capacity factor of 22% would be very poor indeed and would reflect what the then MD of Your Energy admitted in the Berwick Advertiser in October 2004: "The fact that Felkington is on a low lying plateau means the wind conditions are relatively low ...". It would also mirror the fact that the DTI's measured capacity factors for the North East are the lowest in the country (see 'Turbine Efficiency - the Facts'). A good wind resource, and hence capacity factor, is the basic justification for building a wind power station in a particular location.

As far as we can see, the only 3MW turbine that the company might use on this site is described by its manufacturers as a "high wind and offshore turbine". It would clearly be unsuitable for the wind conditions on this site.

'Moorsyde' Mk. III

The company subsequently (March, 2006) submitted an Addendum to its original Environmental Statement [ES] which forms the core of the planning application.

In this document, the company produced their third variation on the figures. This version did not bring any clarification or precision to the figures. On the contrary, it made them so vague as to be almost meaningless.

It stated that the scheme would have a capacity of, "between 28 and 42 megawatts", that the individual turbines would have a rating, "of between 2 and 3 MW" and that "the capacity factor may be between 23% and 30%". Yet even though they claimed to have no idea of the capacity or efficiency of the scheme, they were claiming an output equivalent figure with an additional 500 homes and 4% more of Alnwick District than on their then website calculation which used the 42MW capacity figure!

Yet Another Change (August 2006)

Hard though it is to believe, after axing four turbines from the scheme, Your Energy changed their collective mind yet again.

Apparently, they now could (contrary to their previous arguments) foresee what capacity turbines they would use. The company changed the figures on its website from those submitted to the planning authority in their Addendum to the Environmental Statement. They were now specifying a 3MW turbine, giving an overall capacity of 30MW.

And Another! (October 2006)

YEL changed the figures on their website yet again, it now reverted to being undecided about the capacity of their turbines (2-3MW) in line with the Addendum to the planning application but also finally recognised our arguments on the inaccuracy of their power output equivalents: stating, "Berwick 100% approx" (this 'lost' the equivalent 43% of Alnwick district that they were previously claiming!).

November 2006

YEL now show a 20MW headline capacity for 'Moorsyde' on exhibition materials at Sixpenny Wood published on their website.

Yet Another! (December 2006)

YEL produce yet another set of figures to go with their belated December consultation on the July revision of the 'Moorsyde' scheme. Presented as an update to the Environmental Statement they revert to using a spread of figures supposedly based on 2MW or 3MW turbine models, claiming that, "the Proposal will generate on average 49,600 to 58,800 megawatt hours (MWh) of electricity annually, equivalent to the average annual needs of 10,500 to 12,500 households - between 91% and 107% of the total number of households in Berwick Borough."

As ever, their figures are wildly at variance with the facts on the ground. They claim that, "generation forecasts are based on actual field measurements from June 2003 to June 2005 correlated to long term data at Boulmer (30 miles away) by independent consultants, Garrad Hassan." However applying the bottom end figure to a 2MW turbine gives a capacity factor for the site of 28%. This is wildly unrealistic, considering the wind resource on the site.

Some of their previous calculations which give a factor of 22% bear more relation to reality and the top end figure applied to a 3MW turbine does give a figure of 22%. It should be noted that NPower, at the Toft Hill site next to 'Moorsyde' (with a similar height and topography), are working to a 21% figure which is based on the Met Office wind speed figures for the site. 'Correlating' figures to Boulmer is laughable, it is an exposed coastal site which, as YEL admit, is 30 miles from 'Moorsyde'. We might point out that weather records at Letham Shank weather station, at a similar height to the 'Moorsyde' site and only 7 km. to the north show average wind speeds of under 6 metres per second for the years mentioned above. This figure correlates to the DTI wind speed database figure for 'Moorsyde' and is on the margin of what is normally regarded as viable for development.

Crystal Rig, 330 metres above sea level on an exposed site in the Lammermuirs had a recorded average capacity factor of 27.5% in 2005. (See Data from Ofgem website.) Even Your Energy must agree that 'Moorsyde', on a lowland site only 60-80 metres above sea level, is not likely to outperform Crystal Rig! Even Your Energy's MD has admitted that, "The fact that Felkington is on a low lying plateau means the wind conditions are relatively low ..." (Berwick Advertiser, October 2004).

Using 2MW turbines with a capacity factor of 22%, we arrive at an output figure of ca. 39,245 MWh. Your Energy's claimed output is 26% higher than this figure.

YEL have also produced some figures on projected carbon savings. They estimate that, "a wind farm of the capacity proposed at Moorsyde would annually displace 42,000 to 50,000 tonnes of carbon dioxide (C0₂)". As usual the figures are based on the British Wind Energy Association's formula for carbon saving which, uniquely, does not recognise that significant wind power generation requires, according to National Grid and others, ca. 65% 'hot' backup from fossil fuelled plant and that any power saved will not substitute solely for coal-fired plant.

The DTI, Carbon Trust, DEFRA and Ofgem all state that any substitution should be based on a 'grid average' carbon saving; this immediately halves the figure claimed by YEL. this is before any calculation is made for the enormous amounts of concrete used in turbine foundations - cement production emits large amounts of CO₂ (this figure would be even worse for 'Moorsyde' with grouting of old mine workings in the attempt to provide secure foundations).

You might think that even 20,000 tonnes of CO₂ sounds like a lot. However, we each generate ca. 0.33 tonnes of CO₂ per year merely by breathing. A single jumbo jet, flying from London to Miami and back every day, releases the climate-change equivalent of 520,000 tonnes of carbon dioxide a year. 'Moorsyde', even accepting YEL's dodgy output figures and without making any allowance for 65% standby or building emissions, would save a maximum of 4% of the emissions of a single 747 jet (using DTI/Carbon Trust/DEFRA/Ofgem recommended figure of 0.43kg CO₂ per kWh saved).

Before this proposal is submitted to the Planning Committee, we would ask that Your Energy submits evidenced figures for their application. There has to be a limit to playing games with the figures and the public.

OBJECTION!