Although peat is a widespread substance its physical properties differ from those with which engineers are more experienced. For example, it is mostly water, relatively light and compressible, but has very low internal cohesion. As a continuous deposit that may have accumulated without interruption over several thousands of years it has a two-layered structure that enables water to flow through its top few tens of centimetres. It is waterlogged below, and the anoxic conditions make it an ideal environment for the preservation of human artefacts and even bodies, and of other biogenic indicators of past human activity and climate.

The living biological (biodiversity) resource is concentrated at and above (birds) the surface where growth can take place, but is dependent on maintaining the hydrological and hydro-chemical conditions arising from the long and uninterrupted accumulation of the peat. The growth of the Sphagnum mosses and cotton sedges, so important in the continued accumulation of peat, can only occur where the rain-fed water table remains within a few centimetres of the peat surface for most of the year.

Changes have taken place over time so that much of the UK’s blanket peat is no longer peat-forming, and is described as degraded. The processes involved in degradation, such as the lowering of the water table and the concentration of surface water flow so that the peat becomes eroded from ever-widening gullies, are incremental, and can lead to complete peat loss in locations such as Holme Moss, West Yorkshire. In such areas the peat can no longer support the specific plant cover which makes up its biodiversity importance; and erosion of the peat results in sedimentation and increased colour (dissolved organic carbon) down stream which have negative impacts on water resources, such as drinking water reservoirs. Much of the UK’s upland peat is degraded. It may retain vestiges of its previous vegetation, or contain replacement plant types characteristic of non-peat environments. The UK BAP has a target to restore 70% of the degraded area to active bog. It is against this background, of a mixed intact and degraded resource, that the potential impact of wind farms on deep peat has been assessed.

Wind farm developments can have impacts at the construction, operational and decommissioning stages. The types of impact are common to all stages, and involve: changes in water levels and flow, and dissection of the peat mass, but the duration and intensity varies. In summary, impacts result from the construction of access roads, the casting of turbine bases, the installation of turbines, drainage works associated with the construction process and operation of the site, ongoing maintenance, and then removal of turbines at decommissioning.

Roads may “float” on the peat surface or be cut and filled to the sub-peat base. They require vegetation to be removed, waste peat to be disposed of, non-peat materials to be introduced, the movement of water over the peat surface and through its layers to be interrupted. They change the balance of water availability to different parts of the peat bog and channel surface flow so that is has a greater risk of initiating, or exacerbating, erosion. The digging of voids to caste turbine bases generates waste peat, introduces alkaline concrete and requires some drainage, as do the tracks. Drainage measures have the potential to lower the water level in the blanket bog, resulting in degradation and oxidation of peat. At sites which have a risk of peat slide, there is the additional risk of catastrophic peat failure and landslide. This can have catastrophic consequences for land and the environment, including water resources and fish populations, downstream. The actions taken in construction and operation of wind farms can add to the risk of peat slide.

Although the impacts on intact and degraded bog are much the same, on a degraded bog there are opportunities for the wind farm construction works to include measures that would improve the condition of the degraded bog, which are not present with an intact bog. On all types of blanket bog, how a wind farms is designed, constructed and operated makes a significant difference to how much the blanket bog is affected. Tracks can be designed to reduce the existing erosive forces, and be engineered so as not to create new ones. The blocking of existing drains and moor-grips can lead to beneficial changes towards “favourable condition”, the index of quality condition used in biodiversity assessments.

The ease with which erosion can be triggered, and the amount of material that can be eroded, increases with the depth of the peat deposit. In general, there are far more risks associated with the development of wind farms on deep peat than on peat less than 0.5m thick, or on the fringes around blanket peat. The imperatives for avoiding development on blanket bog sites are greater for those sites with international and national conservation designations. This leaves the remainder blanket bog resource relatively unprotected. These guidelines are intended to ensure that, where there are choices, wise judgements are made, so that the necessary proportion of the resource remains intact for biodiversity improvement and for atmospheric carbon capture in designated and undesignated sites alike.

8 January 2010

naturalengland.org.uk

Download original document: “Investigating the impacts of windfarm development on peatlands in England”

Download the: Appendices and References

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Cuminestown Against Wind Turbines

To begin we refer you to The Economics of Ecosystems and Biodiversity (TEEB) study which is a major international initiative to draw attention to the global economic benefits of biodiversity, to highlight the growing costs of biodiversity loss and ecosystem degradation, and to draw together expertise from the fields of science, economics and policy to enable practical actions moving forward. http://www.teebweb.org/

The access to information in the EIA is grossly inadequate and not in keeping with Equal Opportunities or Social Inclusion legislation.

The fragmentation of information throughout numerous volumes and chapters of the application makes the assimilation of information time consuming and arduous. We question whether the information provided by the developers complies with DDA regulations and whether it is reasonable to expect local people to pay to be able to study the information; or alternatively travel to the nearest large town to view the ES for a short period. This and the other similar applications do not comply with Equal Opportunities or Social Inclusion objectives identified by Westminster and The National Assembly For Wales. With the best will in the world it would be almost impossible for any member of the public to study the documents in the Powys County Council Offices; the documents are difficult to navigate. We also point out that in the hardcopy some pages are not numbered and in the DVD copy the index/contents page does not work electronically: such simple matters left undone, but an example of the standard of this piece of work.

We conclude from information assimilated so far that this application is disproportionate, causing severe degradation of the landscape and social and economic dislocation for only a marginal, or even illusory, benefit. The layout is in conflict with the area and even with other applications. The LANDMAP description of Esgair Cwm Owen Uplands uses positive adjectives (harmonious, attractive) in contrast to adjacent upland areas where wind farms are sited. …

Download original document: “Conservation of Upland Powys – Formal objection to Tirgwynt wind farm application”

Inquiry opened on 9 June 2009; Accompanied site visits made on 2 & 3 July 2009; by Philip Major BA(Hons) DipTP MRTPI, an Inspector appointed by the Secretary of State for Communities and Local Government

Appeal Ref: APP/X1118/A/08/2083682 Land at Paul’s Moor, Wester Bullaford, West Moor, north of Knowstone, South Molton EX36 4QH.

• The appeal is made under section 78 of the Town and Country Planning Act 1990
• against a failure to give notice within the prescribed period of a decision on an application for planning permission.
• The appeal is made by Airtricity Holdings (UK) Ltd against North Devon District Council.
• The application Ref: 45489, is dated 16 October 2007.
• The development proposed is the erection and operation of nine wind turbines and provision of ancillary wind farm infrastructure.

Decision
1. I dismiss the appeal and refuse planning permission for the erection and operation of nine wind turbines and provision of ancillary wind farm infrastructure at land at Paul’s Moor, Wester Bullaford, West Moor, north of Knowstone, South Molton EX36 4QH.

Main issues
37. There are several main issues. These are:

1. The effect of the proposal on the character and appearance of the landscape, and on the setting of the Exmoor National Park;
2. The cumulative effect of the proposal when considered with the proposed developments at Cross Moor, Bickham Moor and Batsworthy Cross;
3. The effect of the proposal on the living conditions of local residents, with particular reference to visual impact and noise;
4. The effect of the proposal on ecology;
5. The effect of the proposal on tranquillity, tourism and cultural heritage.

63. The relatively large extent of the setting of Exmoor which would be covered by this wind farm would, in my opinion, result in visual intrusion to that setting which would be likely to detract significantly from the experience enjoyed by visitors to the National Park. The effect of the wind farm would be to create a substantial area of movement quite out of character with the setting of the National Park. In my judgement this would be seriously damaging to the setting and enjoyment of Exmoor. Whilst I accept that the harm would be geographically limited principally to the southern slopes of Exmoor I believe this to be a key location of the National Park, from which its enjoyment is concentrated in views out to the south.

64. So the effect on the character and appearance of the area, and the setting of Exmoor, can be summarised thus. The visual experience will vary from location to location, and will be of a major and substantial intrusion in places. There would be substantial localised harm to landscape character. But from some places there would be levels of visibility and intrusion which would not, in my judgement, be so harmful as to weigh against the proposal. However, the setting of Exmoor would also be harmfully affected by the extensive nature of the proposal and this would impinge upon the appreciation of the special qualities of the National Park. The proposal would therefore be in conflict with relevant landscape protection objectives of RPG10 Policy EN1, Structure Plan Policies ST1, CO1, CO2 and CO6. In that I have found the proposal harmful there is also conflict with Structure Plan Policy CO12 notwithstanding that part of the site is within the area of search. I also find conflict with Local Plan Policies ENV1c), ENV4 and ECN15A). In the draft RSS there is conflict with part of Policy SD3, Polices ENV1, ENV2 and ENV3.

120. Although PPS22 indicates that renewable energy developments should be capable of being accommodated throughout England, that is qualified by the need to address environmental, economic and social impacts satisfactorily. In this case environmental impacts have not been satisfactorily addressed in my judgement. The scheme as proposed would simply be too harmful in this location and would tip the scales too far against the objectives relating to protection of the landscape and National Park. This is a finely balanced decision and does not mean that all proposals in this locality would be unacceptable, but I find that this one would be. I have considered whether it would be possible to impose conditions to enable the development to proceed, but find that it would not.

Download original document: “Paul’s Moor Appeal Decision”

Inquiry opened on 9 June 2009; Accompanied site visits made on 2 & 3 July 2009; by Philip Major BA(Hons) DipTP MRTPI, an Inspector appointed by the Secretary of State for Communities and Local Government

Appeal Ref: APP/Y1138/A/08/2084526
Bickham Moor, Kirkton Lane, Oakford, Devon EX16 9HB.

• The appeal is made under section 78 of the Town and Country Planning Act 1990 against a failure to give notice within the prescribed period of a decision on an application for planning permission.
• The appeal is made by Coronation Power Ltd against Mid-Devon District Council.
• The application Ref: 07/02262/MFUL, is dated 20 November 2007.
• The development proposed is the construction and operation of a four turbine wind farm for electricity generation, including ancillary buildings and activities, with a maximum rated output of 12mw.

Decision
1. I dismiss the appeal and refuse planning permission for the construction and operation of a four turbine wind farm for electricity generation, including ancillary buildings and activities, with a maximum rated output of 12mw at Bickham Moor, Kirkton Lane, Oakford, Devon EX16 9HB.

Main issues
36. The main issues in the appeal are:

1. The effect of the proposal on the character and appearance of the landscape, and on the setting of the Exmoor National Park;
2. The cumulative effect of the proposal when considered with the proposed developments at Three Moors, Cross Moor and Batsworthy Cross;
3. The effect of the proposal on the living conditions of local residents, with particular reference to visual intrusion and noise;
4. The effect of the proposal on ecology;
5. The effect of the proposal on tranquillity, tourism and cultural heritage

50. The height of the site in relation to surrounding land also means that within about 3km, where visible, the turbines would tend to be stark skyline features. There would be nothing to relieve the skyline impact unless vegetation close to the viewer was able to mitigate public views. Taken in the round, though, and whatever opinion is formed on the attractiveness or otherwise of the turbines as structures in themselves, the wind farm would appear as being drastically at odds with the character and appearance of the local landscape.

57. So the effect on the character and appearance of the area, and the setting of Exmoor, can be summarised thus. The visual experience will vary from location to location, and will be of a major and substantial intrusion in places. There would be serious harm to landscape character. But from some places there would be levels of visibility and intrusion which would not, in my judgement, be so harmful as to weigh against the proposal. I consider that the skyline views and movement of blades would, notwithstanding the separation from Exmoor, impinge upon the appreciation of the special qualities of Exmoor to a material degree. The proposal would therefore be in conflict with relevant landscape protection objectives of RPG10 Policy EN1, Structure Plan Policies ST1, CO1, CO2, CO6 and CO12. There is also conflict with Local Plan Policies S5v) and S6i) & xvi), and Core Strategy Policies COR2c) and COR5a). Given that I find the proposal harmful there is also conflict with Core Strategy Policy COR18. In the draft RSS there is conflict with part of Policy SD3, Polices ENV1, ENV2 and ENV3.

113. The factors which compete here are the clear: serious harm to landscape and to the special qualities of the National Park, with resultant conflict with the development plan policies and national advice; this is set against the undoubted support offered by other development plan, national and unmerging policy for developments such as this which are required to combat climate change.

114. In this instance, whilst recognising that the need to increase renewable energy capacity and to reduce CO2 emissions is of crucial importance, I cannot agree that the balance lies in favour of development. PPS22 indicates that renewable energy developments should be capable of being accommodated throughout England, but that is qualified by the need to address environmental, economic and social impacts satisfactorily. In this case environmental impacts have not been satisfactorily addressed in my judgement. The harm I have identified, to the local landscape, to the setting of Exmoor, and cumulatively with other proposals, in addition to the uncertainty surrounding the protection of living conditions, would simply be too great. Apart from the conflict with policy noted above, this also leads to conflict with Local Plan Policy ENV2iv). The production of renewable energy, important as it is, does not justify the development, even for a time limited period of 25 years. The balance is too heavily weighted against the proposal in this case. I have considered whether the imposition of the suggested conditions would mitigate the harm identified but conclude that they would not.

Download original document: “Bickham Moor Appeal Decision”

Inquiry held on 16-23 October 2009; Site visits made on 23, 27, 28 October 2009 and 13 January 2010; by Robin Brooks BA (Hons) MRTPI, an Inspector appointed by the Secretary of State for Communities and Local Government

Appeal Ref: APP/M0933/A/09/2099304
Sillfield, Gatebeck, Kendal, Cumbria LA8 0HS

• The appeal is made under Section 78 of the Town and Country Planning Act 1990 against a failure to give notice within the prescribed period of a decision on an application for planning permission.
• The appeal is made by Sillfield Wind Cluster Ltd against the decision of South Lakeland District Council.
• The application Ref SL/2008/0900, is dated 8 September 2008.
• The development proposed is erection of three wind turbine generators and associated infrastructure.

DECISION
1. I dismiss the appeal and refuse planning permission. …

10. Bearing in mind the aims of the above policies, and as set out at the Inquiry, I consider that there are five main issues in the appeal, namely:

1. the effects of the proposal upon the character and appearance of the surrounding landscape;
2. the cumulative impact of the proposal upon the character and appearance of the surrounding landscape, taken together with other similar developments, both existing and proposed and, in particular, that at Old Hutton1;
3. the effects of the proposal upon the living conditions of local residents, particularly in terms of visual impact, noise and shadow flicker;
4. the effects of the proposal upon enjoyment of the countryside by members of the public, including those using local rights of way; and whether approval would have any significant adverse effects on the contribution made by tourism and recreation to the local economy; and
5. the contribution that the proposal would make to achieving regional and national targets for renewable energy generation, bearing in mind extant and emerging national planning policy; and the extent to which any such contribution should be weighed against any adverse impacts in terms of the other issues.

83. Nor do I accept the Appellants various arguments that the imperative to increase renewable energy generation capacity is such that only the most severe or widespread environmental impacts are capable of outweighing it; or that proposals such as that at Sillfield, affecting land with no designations of national or regional value, should not be refused because of local landscape impacts; or for reasons other than the most compelling purpose, pitched at the level of a national rather than local interest. PPS22 does not depart from the principle that planning proposals should be assessed on their individual merits and there is no indication in statements of policy since that visual and landscape effects are to carry less weight than hitherto. Thus whilst one of the most recent such statements, the UK Renewable Energy Strategy published in July 2009, states that the planning system must be speeded up and made more predictable in the way that it deals with proposals for renewables, it includes the caveats that we must also continue to protect our environment and natural heritage and respond to the legitimate concerns of local communities.

84. In my analysis of landscape impacts I have noted the quiet charm of the local countryside and, whilst it carries no formal designations, this does not mean that it should be implicitly downgraded. …

89. The harm to the living conditions of local residents through the turbines dominating the outlook from nearby properties is also a compelling objection to the appeal proposal, whether it is assessed on its own or in combination with Armistead (issue (iii)). Given the severity of the harm to individual properties, the fact that relatively few dwellings are affected is not in itself significant. …

90. … I have also borne in mind the fact that planning permission is sought for a period of 25 years. However, as such a time period is roughly a third of an average lifetime I have some difficulty in regarding it as “temporary” in any real sense. If the turbines would cause significant harm to landscape character, as I believe is the case here, that harm would not be made more acceptable by the prospect of their ultimate removal.

Download original document: “Sillfield Appeal Decision”

With power grids strained due to heating demand, increments to generating capacity are to be welcomed. But along with the usual hoopla about homes served and CO2 emissions savings, it is time for some “devil’s advocacy” by asking: – how much energy and capacity will this project really create? How much CO2 will be saved? And when the chips are down will consumers and grid operators be pleased that their funds have gone into wind rather than into some other generating source?

We strongly suspect that neither consumers nor grid operators will benefit greatly from this plant. Our brief analysis of this announcement shows that the claims for houses served and carbon saved are not supported, though some incremental, useful energy supply may be possible under some circumstances. All such claims depend on the system operator’s ability to use the wind farms’ output to offset hydro generation, the key generation resource in the Northwest United States (NW).

Contributing to Capacity: The Sine Qua Non of Power Generation Investments

In the service area where the new wind project will be located, total generating capability is 84 GW. Hydro accounts for 60% of this total (nominally). Current peak demand in the NW power pool, into which the wind project will inject energy, stands currently at just over 60 GW, about the same size as the UK grid. In the winter season provisions for other claims on the water (irrigation, flood control, endangered species protection, etc.) reduce the available capacity of hydro by some 7 GW. The pool’s own capacity assessment notes that “A severe weather event for the entire Power Pool area will add approximately 6,000 MW of load while at the same time reduce [sic] the capability by 7,000 MW.”

In other words, when the chips are down, hydro’s contribution to meeting a larger peak demand may fall by as much as 7 GW, with another 6 GW less capacity from other generation sources. Let’s do the arithmetic: the “normal” winter peak (50% probability) is 61 GW, generating capability (not the same thing as firm capacity) is 84 GW. Comes the storm and the peak rises to 67 GW, while the “capability” falls to 71 GW, providing just a bit more than the minimum reserve requirement of 5 GW.

How likely is it that wind can add to capacity in the midst of a winter demand surge and capacity restriction? From recent UK experience, not bloody likely. The following table was taken from the UK system operator website for the first week of January 2010; most days since the middle of December 2009, when winter weather gripped the nation, have looked similar.

The outstanding performer is gas-fired CCGT technology, ~34% of capacity and 38-40% of output. Coal and nuclear supply almost all the rest of the capacity and energy. So where is the wind? The UK, with more than 4 GW of wind generation capacity (~6% of total), saw essentially no help from wind in meeting demand during this entire period. With wind’s contribution to capacity ranging from just over 100 MW to about 500 MW for much of the crisis period, about a 2.5 – 9% capacity factor, and with wind’s contribution to energy at less than 1% for days on end, one would be hard-pressed to attribute much of a peak contribution to a large wind project in Oregon.

235,000 Homes Served? Is This Claim Likely or Even Possible?

The claim is that the project will provide enough energy to power 235,000 households. Assuming a generous capacity factor of 30 per cent this yields a reasonable average annual household use of:

845 MW × 1,000 (convert to KWh) × 0.30 × 24 (hours per day) × 365 (days per year) / 235,000 = 9,450 KWh per household

A reduction in capacity factor to 25 per cent reduces the households served to about 176,000. Is this a reasonable consideration? Recent experience world-wide shows that capacity factors are often less than that.

But these calculations rely on a measure that reflects the aggregate annual consumption. A more realistic representation would be based on meeting the peak demand per home, which is estimated to be approximately 1.5 kW. How do wind plants perform on this basis? Using the more applicable measure of capacity value (sometimes called capacity credit and explained further below), the proposed project will theoretically generate enough energy to meet the needs of about 49,000 households, at a cost of more than $2 billion for initial investment. Over a 20-year lifetime that electricity will cost the NW Power Pool about 17 cents/kWh for “average” power, and some of the costs can be made to “disappear” through the use of state and federal tax credits and other subventions. It is not easy to calculate a “firm” supply cost for wind, given the absolute reliance on backup, but this is in addition to the above 17 cents/kWh. For the kind of money that wind costs the pool could supply diesel generators to neighborhoods for an investment of less than $600 million and contribute a firm 845 MW at about 20 cents per kWh (including fuel). Those diesel units could reliably meet the peak demand needs of more than 563,000 households as follows:

Given an average peak requirement of a household, equal to about 1.5 kW, and assuming a coincident peak, then a firm 845 MW of generation, as supplied by the diesel units, can meet the needs of about 563,000 households.

i.e., 845 MW × 1,000 / 1.5 = 563,333 households

Even using the possibility that some of the diesel units would be unavailable, probably 2-3%, the number of households that could be served at peak reliably would still be more than 546,000 (97% plant availability at peak).

Wind cannot be relied upon to provide firm generation at full capacity coincident with peak demand. Wind might be capable of contributing to the peak demand requirements of the system at some times. However, this will rarely happen, and when it does it will be for brief periods. In these circumstances, the expectation of the number of households served will be just over 49,000. To calculate this it is necessary to introduce the factor representing the statistical expectation of wind production at peak demand times. This is capacity credit, or capacity value, which brings a number of considerations into play, but typical experience, and the figure used by the Texas system operator, is 8.7 per cent.

i.e., 845 MW × 1,000 × 0.087 / 1.2 = 49,010 households

In spite of all statistical expectations of output from wind generators, these households will not be served reliably in any manner that meets their needs. Taking this out of the comparatively benign case of households, can you imagine a hospital, a school or a business relying on an electricity supply dominated by wind? Calculations that are based on aggregations summed over a year and averages do not reflect the real world, which operates in real time.

For significant periods of time, no households will be served, as was demonstrated by the UK data. For almost all of the time, the electricity supply will be so unreliable as to be useless. If there were some way to store the wind-plant electricity produced, then some of this would make sense. Even granting such a widely available storage capability, there would be considerations of the relationship between the storage being filled compared to the draw on it, again in real time. Annual aggregations and averages are not a reasonable way to look at the fluctuating performance of industrial-scale wind power.

The message that emerges from both the calculations and experience is that claims regarding homes served by industrial wind power are not valid measures of wind’s value. The true measure of value is the displacement of hydrocarbon fuel and reduction in CO2 output by the power generation system. As shown in previous articles, the need for shadowing and backup generation to ensure that load can be met despite fluctuations in wind output may result in little or no net decrement to fuel use or emissions.

However, our analysis shows that under some circumstances integration of industrial scale wind may permit small reductions in shadowing and backup fuel use, provided there is sufficient excess hydro capacity. For the Oregon wind farm case, wind would seem to be specifically excluded from meeting winter peak demand. However, wind may be able to contribute somewhat to meeting energy demand in the off-peak seasons.

In Part 2 we consider under what conditions and to what extent an industrial wind facility may save fuel or reduce CO2 emissions.

Part 2

Press reports in the Financial Times and other news outlets describe a project with 338 wind machines of 2.5 MW each, giving a total capacity of 845 MW. The project sponsors claim that they will provide enough energy to serve 235,000 households and reduce CO2 output by 1.5 million tonnes annually. In Part 1 of this article we showed that the claims for households served are fanciful. In reality, no more than 49,000 households could be “supplied”, and these with only a minimal degree of assurance. Indeed, the wind project is more costly than a diesel backup scheme that would actually be capable of supplying reliable power to several hundred thousand households. The wind project is also three times more costly than a replacement of just 211 MW of older coal capacity with new technology that would provide a similar reduction in emissions while supplying firm power to the NW Power Pool’s customers.

The key to wind providing some degree of fuel and emissions savings is its ability to deliver reliable electricity without shadowing or backup by hydrocarbon-using plants. These shadowing/backup requirements in the NW Power Pool may be able to take advantage of existing surplus hydro capacity in that region during off-peak periods (spring and fall), thereby permitting the proposed plant to reduce hydrocarbon consumption and emissions somewhat during those periods. It is not reasonable to expect to achieve the claimed emissions savings, but lower figures, less than half the publicized savings, may be possible.

In particular, the addition of wind generation, with shadowing/backup provided by reservoir hydro, may be able to reduce overall CO2 emissions in California, the ultimate customer for the electricity produced by the GE project during Oregon’s 2 surplus seasons. During the winter and summer peak demand periods less hydro output is available, peak demand is greater and the shadowing backup will be provided by some combination of gas-fired and coal plants. What is critical to keep in mind is that maintaining stability in the NW Power Pool requires the pool to shadow/backup not only the proposed new project, but the other 6.4 GW of existing wind as well.

This analysis shows there are less costly and more effective alternatives readily available that rival or exceed the claimed benefits of this wind project.

Wind Shadowing/Backup Requirements

So what is needed to ensure wind plants deliver reliable electricity? They have to be paired with conventional, reliable generators capable of mirroring wind’s volatile and unreliable output. This can be called wind shadowing/backup capacity. It is shadowing wind when wind is producing, albeit it in a volatile manner. It is backup to wind, in the more usual use of the word, when wind is producing nothing, which can be for extended periods.

When claims are made about wind displacing fossil fuel plant production, the question that should be asked first is: what is providing wind shadowing/backup? With system reliability and power quality considerations coming to the fore, it becomes evident that the shadowing/backup is what is displacing the fossil fuel production, and wind is displacing some small measure of the shadowing/backup. An earlier article explored the realities of this and showed that a wind project that relies on fossil generators to shadow the wind machines may provide little net fuel or CO2 displacement and in some cases may actually increase fuel use and emissions. The latter result may obtain as a result of: (1) the imposed inefficient operation of the wind shadowing/backup, as well as (2) use of shadowing/backup technologies that are less efficient than the pool’s major generation resources – coal, nuclear, gas-fired combined cycle. The three generation sources listed above are in varying ways not generally suitable for providing shadowing for wind. In each case the ramp rate of the generator is too slow in reacting to many of the transients of wind production. Consequently, shadowing and backup must be provided by smaller, faster acting, but less efficient engines. If the shadowing/backup requirements are significant – that is, if wind output is large relative to overall system capacity, even approaching 5% – then the reliance on small, inefficient engines or combustion turbines (GTs) will arguably lead to a net increase in fuel use and therefore emissions.

The general considerations are:

• Wind shadowing/backup must be able to respond to wind’s volatile nature, and candidates, with varying degrees of ability to do this, include gas turbine, coal, hydro and small diesels.
• What generation capacity mix will be displaced by the combination of wind and shadowing/backup.
• As the junior member in the mix, wind replaces the shadowing/backup for purposes of CO₂ emissions calculations.

Normally, the full and accurate computation of the technologies involved in shadowing/backup of wind will require a system dispatch model so that minute-by-minute variations in wind output can be shadowed by fast ramping engines or valves (hydro). Table 1 summarizes some of the possible scenarios.

Table 1 – Some Wind Shadowing/Backup Scenarios In the NW Power Pool

In scenarios A, B and C, the inefficiencies imposed by wind volatility on the shadowing/backup plants can more than offset the CO2 emissions “saved” at the point of wind generation. In any event, Scenario C is relevant in the NW Power Pool only insofar as coal is used as a resource in the pool, and coal-fired electricity enters this pool largely through imports. In case D, assuming no curtailment of wind during high wind production periods and no spillage of hydro is required because of the timing of wind production relative to reservoir levels, the wind production could be replacing that of fossil fuel, as indicated by “Other”. In case E, wind is replacing hydro and no CO2 emissions are saved (generally wind acts similarly to run of river hydro, in terms of system stability, with the exception of such cases as hydro plants at Niagara). Note that the conditions for case D are seldom met during annual peak demand periods in the NW Power Pool, as noted in Part 1.

The Oregon wind plant production is slated to go to Southern California Edison, which obtains over 50 per cent of its electricity from imports (out of state) and almost 40 per cent from thermal generation within its jurisdiction. As California as a whole gets 50 per cent of its in-state generation from natural gas and about 2 per cent from coal/oil, it is reasonably assumed that the wind/shadowing-backup combination is displacing gas, mostly in combined cycle plants. It is possible that some imported electricity is being displaced, which likely contains a higher proportion of coal.

The question remains: what is being used as wind shadowing/backup? Oregon has the following electricity production profile – hydro 61 per cent, gas 27 per cent, coal/oil 8%, and other renewables 4%. A reasonable assumption is that impounded hydro is being used within Oregon for this purpose during shoulder seasons (spring and fall), while gas and possibly coal are used during peak seasons (Summer and Winter). In off-peak seasons in Oregon and the NW Power Pool, case D generally applies and Oregon is basically exporting hydro and some wind. Case A or B applies during peak seasons, and gas or coal is likely exported.

CO2 Emissions Saved From Wind Generation

The foregoing illustrates the complexity of determining the impact of wind plants on fossil fuel and CO2 emissions reductions in electricity systems. The following completes the application of this to the new Oregon wind plant.

The wind project sponsors claim that 1.5 million tons of CO2 emissions per year will be saved as a result of this investment. Accepting the premise that no shadowing/backup will be needed the most likely result is for the wind to displace gas-fired CCGTs, at 0.4 tons CO2 emissions per MWh:

845 × 0.30 × 24 × 365 × 0.40 = 890,000 tonnes or about 0.9 million tonnes per year

For a 25 per cent capacity factor, more reasonable for onshore facilities, the CO2 emissions saved become about 0.7 million tonnes per year. The actual savings are likely to be far less than this calculated figure, since hydro capability is reduced during the winter peak demand period, one that coincides with troughs in wind availability as well. As a result, and as indicated above, the NW Power Pool is likely to be exporting gas/coal generated electricity to Southern California during the winter demand peak as well as during the summer peak. In fact, any coal-generated electricity exported to cover the supply obligation of the wind farm is likely to come from the same plants in Utah, Montana, Arizona and Nevada that currently provide the overall grid stability for Southern California Edison and California in general – a contractual round trip that contributes little or nothing to net energy supplies and saves little or no fuel/emissions.

It should be noted that potential savings of fuel/emissions during shoulder periods (fall and spring) comprise a special case because of the large hydro capability in Oregon during such periods. In the more general case and during the summer and winter peak demand periods, with gas or coal used for wind shadowing/backup, the CO2 emissions savings would reverse and net fuel use/emissions would rise due to the inefficiencies imposed on these plants. In fact with wind, currently at 6.4 GW, expected to approach 10% of pool generation capability in the NW Power Pool with the new project, the ability of the smaller, faster responding and more efficient shadowing engines described in Power Magazine are likely to be impracticable, since more than 800 of such engines would be required, meaning that shadowing/backup will be supplied by gas turbines, with the attendant inefficiencies and high fuel consumption, especially during startup. During lulls in wind a system of this size will require significant conventional generation resources for shadowing/backup.

At this point, a reasonable expectation is that half of the reduced CO2 emissions shown above would be achieved, given that the generation savings are valid for roughly half the year, spring and fall seasons; that is:

50% of 0.7 = 0.35 million tonnes per year

Since providing shadowing/backup for the NW Power Pool’s overall wind generation capacity of 7.3 GW, including the proposed GE project, involves large combustion turbines, then the fuel used just for startup, about 8-10 tonnes for each turbine each time, needs to be debited from the emissions reductions account to the wind plant. Each startup cycle, using liquid fuel or pressurized gas, produces about 100 tonnes of CO2 . To back up the NW Power Pool’s wind capacity would put roughly an additional 90 million tonnes of CO2 into the air, that is:

75 units × 12 start ups for each x 100 tonnes CO2/startup = 0.090 million tonnes per year

The GE project’s share of the shadowing/backup startup CO2 emissions (~11%) would be roughly 9,900 tonnes, offsetting about 3% of entire calculated CO2 savings for the 845 MW project.

Emissions savings identical to those claimed for the new wind project can be accomplished at significantly lower cost simply by replacing older coal-fired power plants (<35% conversion efficiency and relatively dirty) with current “ordinary” coal fired plants (~41% efficient and much cleaner). “Ordinary” current technology would reduce emissions in the pool by 0.22 million tonnes/year for 211 MW of firm capacity, roughly the amount of energy that the proposed wind project generates. Higher technology coal plants (~45% efficient and very clean), more efficient still, will reduce emissions by more than 0.35 million tonnes/year for the same amount of electricity generated by 845 MW of wind. As noted previously on this blog, many willing investors are anxious to make such investments. Only a perverse system of government permits and approvals and uninformed environmental groups stands between newer combustion technology and improved power supply. These are truly the “shovel-ready” projects.

The costs to the electricity consuming public for emissions reductions on the order of what is produced by the proposed Oregon wind plant are less than one half what will be required to keep the new wind project in operation and shadowed/backed up properly. An investment of a similar magnitude to the wind plant in high technology coal combustion, by replacing roughly 1,000 MW of older, less efficient, dirty coal generation capacity, would reduce emissions of CO2 (and a lot of other things like SOx and NOx and mercury) by more than 1.65 million tonnes annually, more than five times the emissions reductions that can be credited to the wind plants with the plus of a substantial improvement in grid reliability. Investing $1.9 billion in new high efficiency coal plant of 845 MW could replace older ones and reduce emissions considerably. Alternatively, such a plant would serve 600,000 additional household customers in the NW Power Pool or Southern California for about 6.5 cents/kWh, roughly one third the cost of wind, including its shadowing/backup requirements without the need to resort to arithmetic sleights-of-hand about reliability.

Conclusions

The considerations of wind availability, system operations and hydro availability are likely to be more complex than the treatment given here. However, a more complete system simulation is unlikely to be more favorable to wind than is the present treatment, especially if increased reliability standards are implemented for power pools. The proposed CO2 savings from the Oregon wind project are overstated to a significant degree and it is likely that net fuel/emissions savings will only be possible during periods of surplus hydro availability – the off-peak spring and fall seasons.

The lesson from this case is that reported claims of benefits from the introduction of industrial wind plants, such as, households served and CO2 emissions saved should be carefully reviewed – they are generally difficult to support.

And since wind competes with other projects for investment capital the funds that are devoted to wind may actually reduce potential emissions savings from efficiency and technology improvements in coal, improvements that can be supplied without tax credits or other fiscal chicanery.

[from masterresource.org (part 1 and part 2)]

Summary
New evidence released by the Dept. of Energy and Climate Change (DECC) under a Freedom of Information (FOI) request shows that Government suppressed a recommendation by its own acoustics consultants to tighten current noise regulations on wind turbines in order to protect local residents from night time noise. This does little credit to the Department, and must be corrected immediately.

Introduction
In 2006 the Government published a crucial report on wind turbine noise and its effects on nearby residents by Hayes McKenzie Partnership (HMP) . This study has been used to support the view that there is no reason to revise existing Government wind farm noise guidelines, nor that there are any health ramifications of turbine noise at neighbouring dwellings.

Mr Mike Hulme of the Den Brook Judicial Review Group, a group of local residents opposing a wind turbine development close to their houses in Devon, submitted an FOI request asking to see all draft versions of this study.

The Government, that is the DECC, refused the request, claiming that it was not in the public interest for these to be released.

Mr Hulme appealed against this decision, and the appeal was upheld by the Information Commissioner. Consequently the Government has been obliged to release earlier drafts of the HMP report.

The drafts reveal that the final published report silently removed earlier recommendations that:

• the night time wind turbine noise limit should be reduced from 43dB to 38dB, and
• in the event that the turbine noise has a discernible beating character, the limit should be further reduced to 33dB.

The DECC had sought to suppress the drafts, claiming that it was not in the public interest for these to be released. However, the Information Commissioner overruled DECC. The Commissioner’s report says:

the Commissioner is conscious that climate change and the need to seek safe and viable alternatives to fossil fuels are major political issues. Therefore, the Commissioner believes that disclosure of this information could be used to feed into the debate with regard to what role wind farms should have in seeking to reduce the UK’s carbon emissions and how that should be balanced with regard to the potential effect that wind farms could have on people’s health.

Read more:

• Commentary in full; click here
• ICO findings; click here
• Released draft HMP reports; click on: Draft 1; Draft 2; Draft 3
• The released emails; click here
• Final report; click here

8th December 2009

denbrookvalley.co.uk

When the new wind farms start to generate for the national grid, we know they will deliver power inconsistently. As soon as the wind speed drops below that required to generate maximum output, (nominally 15 m/s), the power flow starts to reduce significantly. When the wind reaches a minimum speed (nominally 4 m/s) all power stops flowing (Figure 1). This deficit has to be immediately replaced by power from other generating plants. Presently, there are no other credible sources of renewable energy, which can be marshalled to pick up this deficit. It will fall to the fossil fuel powered stations to generate the shortfall well into the foreseeable future.

As the wind is a fickle source of energy and will, on occasions, deliver no power at all the alternative standby capacity will need to equal the total installed wind turbine capacity (see Figure 2). This will require, in effect, the provision of double the installed capacity of electrical generating equipment. All this plant must remain economically viable if the network is to provide security of supply.

Considering the predictable performance of a wind farm over a period of one year, the actual output is approximately 30% of its installed capacity. Although the standby power plants must be capable of producing 100% of the power requirement, they, will need to recoup their fixed overhead costs from generating just 70% of their capacity. Hence the price of the power they generate will need to rise in comparison with today’s current base load price to meet the short fall in revenue. When this is taken into account the real cost of wind power will be even higher than the incremental price paid to wind generators.

At the present time there is sufficient installed capacity to meet these transient requirements but much of this plant is well into its useful life and will need to be replaced during the next decade. It is at this point that a major problem arises.

The real carbon dioxide reduction achieved by the use of wind turbines is not a simple calculation. While it is true that the wind delivers energy, without emitting carbon dioxide, it does not take into account the process which replaces it when the wind fails.

As an example, consider 1GW of installed wind turbine capacity, which as we have seen would deliver an average clean output of approximately 300MW over the period of one year. Clearly, it would cycle between 1GW and 0GW during the period and this would require a back up power station of 1GW capacity to deliver the required make–up on demand.

The environmental impact of this replacement generation will depend upon the type of fuel used and the efficiency of the power plant.

Comparing carbon dioxide emissions

The approximate carbon dioxide liberated per GJ of heat output for specific fuels.

(source: Renewable Energy, Boyle 1996)

Type of Power plant	Plant efficiency
Direct Coal Fired	34-35%
Direct Oil Fired	34-36%
Open Cycle Fired	34-36%
Combined Cycle Gas Turbine (CCGT)	54-56%

Hence the quantity of CO2 liberated by generating a continuous output for a period of one year can be calculated for various fuels:

e.g. For a power station continuously generating 1GW of power (where 1 GWh = 3.60 × 103 GJ and 1 year = 8760 hours) the total energy produced is:

And for a coal fired power plant of 35% efficiency the total quantity of CO2 produced is therefore:

Similarly, carbon dioxide liberated per GW generated continuously for one year (8760 hours) from different fossil fuels is:

The new wind generators will come on stream during the next five years and may be expected to generate power for twenty-five to forty years. During this time the early years of the make-up power will come from the existing fossil fuel power plants. Many of these units, however, are already half way through their working lives and will have to be replaced during the next five to fifteen years.

Furthermore, the current Combined Cycle Gas Turbine (CCGT) units are not well suited to follow the demand load changes on the network as the boiler/steam turbine units respond slowly to major load swings. And when the transient output from the wind turbines is added to the fluctuating nature of customer demands, the picture of the network supply requirements becomes even more unpredictable.

The potential consequences of wind power

If a 1GW wind farms generates power to the grid during all the periods when wind is sufficiently powerful, it might be expected to deliver approximately 2,630 GWh per year. However, this would cause a short fall against a 1GW base load demand (ie. 8760 GWh) over the same period of approximately 6,100GWh and this has to be generated by fossil fuels.

The consequences are summarised in the table below:

The data demonstrates that at best a wind turbine farm of 1GW installed capacity would save approximately 0.85m tonnes of carbon dioxide annually if it displaced an efficient CCGT plant. By the year 2010 a number of the current CCGT stations will be more than twenty years old and approaching the de-commissioning phase. If the financial incentives are inadequate (as is the current position) and the base load market is not available to help defray capital and fixed operating costs, they will not be replaced. The technology of any such new plants will also need to have been developed to handle the transient nature to the demand after the wind farms have produced their volatile output. The supply of natural gas will need to be reliable and economically priced but by this time it will be imported from politically less stable sources.

If the gas fired units are not available, the supply would have to come from either oil or coal fired plant (or even new open cycle gas fired plants). This would cause carbon dioxide emissions to increase above their current best levels.

In the case of oil fired back-up, the increase is some 1.9 m tonnes greater than the current position would be where the whole load is supplied by a gas fired CCGT plant. If the comparison is made with a coal fired plant supplying the make-up, the increase in carbon dioxide would be 4.6m tonnes annually.

And these figures will be eight times greater if the wind turbine installed capacity reaches the government’s target of 8GW.

It is worth noting that the government is committed to reducing the carbon dioxide emissions by 26.5m tonnes annually by 2010. A significant proportion of this reduction is planned to be delivered by wind turbines. This analysis suggests that the current ‘Dash For Wind’ could actually make the situation worse.

Robert J Bass and Dr Peter Wilmot
School of Mechanical and Manufacturing Engineering, Loughborough University
UK Power, Issue 2 (2004)

For further information, contact Mr Robert J. Bass on Tel: 01780 763024 or Dr Peter Wilmot on Tel: 01509 227 555.

The development proposed is the construction of 13 wind turbine generators (up to 125m in overall height) c/w electrical control room & compound area, new & improved access tracks, underground cabling, 80m anemometry mast, ancillary works and equipment; temporary construction works; new vehicular access from the minor county road; removal of conifer forest.

Decision: I dismiss the appeal.

Main issues: I consider that the main issues in this case are the visual effects of the proposal, both within the locality and from more distant views such as from the Clwydian Range Area of Outstanding Natural Beauty (AONB); and the effects of noise on the amenity of residents within the locality.

Overall Conclusions: I conclude that this proposal would be in serious conflict with the appropriate UDP policy. The benefits of the provision of renewable energy would not outweigh the harm I have identified. The imposition of conditions would not overcome these strong planning objections. Therefore, for the reasons given above, I conclude that the appeal should be dismissed.

[Importantly, as the developer had noted, "The site is in Area A of the Strategic Search Area (SSA) as designated by the Welsh Assembly Government (WAG) in Technical Advice Note 8 (TAN 8). Gorsedd Bran also sits within the refined area as designated by the joint Denbighshire/Conwy County Council Interim Planning Guidance (IPG). Despite being within a designated wind farm development zone and contrary to the recommendation of Council Planning Officers the scheme has been refused planning consent."]

Download original document: “Appeal Decision – Gorsedd Bran, Nantglyn, Wales”