REGEN SW Wind Resource Assessment for the South West Following ...
REGEN SW Wind Resource Assessment for the South West Following SQWenergy Methodology
July 2010
REGEN SW Wind Resource Assessment for the South West Following SQWenergy Methodology
CONTENTS 1
INTRODUCTION......................................................................................................................... 1
2
METHODOLOGY ........................................................................................................................ 1
3
4
5
2.1
Large Scale Wind Resource................................................................................................. 1
2.2
Small Scale Wind Resource................................................................................................. 5
RESULTS .................................................................................................................................... 6 3.1
Large Scale Wind Resource................................................................................................. 7
3.2
Small Scale Wind Resource............................................................................................... 10
CONCLUSIONS ......................................................................................................................... 12 4.1
Large Commercial Scale Wind Resource ........................................................................... 12
4.2
Small Scale Wind Resource............................................................................................... 14
RECOMMENDATIONS.............................................................................................................. 15 5.1
Large Scale Wind Resource............................................................................................... 15
5.2
Small Scale Wind Resource............................................................................................... 15
TABLES Table 2.1: Feature Offsets.................................................................................................................. 3 Table 2.2:Exclusion Area Offsets ........................................................................................................ 4 Table 2.3: Scaling Factors................................................................................................................... 6 Table 3.1: Large Scale Wind Resource ................................................................................................ 7 Table 3.2: Small Scale Wind Resource .............................................................................................. 10
FIGURES Figure 3.1: Large Scale Wind Annual Energy Production..................................................................... 8 Figure 3.2: Small Scale Wind Annual Energy Production................................................................... 11
APPENDICES Appendix 1: Local Authority Large Scale Wind Resource Level Maps Appendix 2: Local Authority Small Scale Wind Resource Level Maps 42-0336/REN/267 July 2010
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1
INTRODUCTION
This report details the methodology used to update the South West wind resource assessment originally undertaken as part of the Renewable Energy Atlas and Revision 2020 projects completed in 2006. This re-assessment of the wind resource has followed guidance from the SQWenergy report entitled “Renewable and Low-carbon Energy Capacity Methodology – Methodology for the English Regions” issued by DECC in January 2010. 2
METHODOLOGY
The methodology is divided into two sections which detail how the resource for the large and small resource assessments have been undertaken. The resource assessment for each scale was started from a layer comprised of the South West boundary clipped to the high tide line. The polygon was then split by the NOABL wind speed one kilometre grid and ward boundaries. The wind speeds at 85m and 10m, Ward names, District names, Local Planning Authority and County names were saved as attribute fields to each of the split polygons. The potential wind resource is expressed in four different features:
Energy (GWh/yr or MWh/yr)
Percentage contribution to the South West regions annual electricity demand (26267GWh/y)
Percentage contribution to the South West regions total annual consumption (130920GWh/y) - Electricity and total energy consumption figures were taken from DECC’s 2007 report.
The carbon saving (0.537kg of carbon / kilowatt hour of electricity produced DEFRA).
2.1
Large Scale Wind Resource
The resource assessment for large scale wind used the following methodology and benchmarks to establish the values described above. A wind speed up log law calculation was used to estimate the wind speed at 85m above ground level from the 45m reference height in the NOABL database.
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A surface roughness value of 0.03 was used in the
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calculation. The resultant speed up factor applied to the 45m wind speed values to derive the wind speed at 85m was 1.087. The installed generating capacity was estimated based on land area within each ward, district, planning authority and county boundary. This was based on the benchmark figure of 9MW/km2 from the SQW methodology. The number of turbines for each area was back calculated from the installed capacity by dividing it by 2.5MW, the turbine capacity suggested in the SQW methodology. A Nordex N80 2.5MW turbine was subsequently used as the reference turbine for energy calculations, etc.
This turbine is representative of the scale of turbine used in large commercial
windfarms. Each discrete area falls within a specific 1km grid square with an identified wind speed at a reference height of 85m. The total number of turbines within these discrete areas was then used as a multiplier on the annual energy output for a single N80 Nordex turbine derived from its energy curve at the given wind speed. The SQW methodology identifies several resource levels for large commercial scale wind turbines. Cumulatively each level further constrains the resource. Each level is detailed below. 2.1.1 Level 1 – Natural Resource Level 1 gives the total natural wind resource, utilising all the land within the South West without exception. 2.1.2 Level 2 - Benchmark Figures No meaningful output could be achieved at level 2 as this simply defines the turbine capacity and the packing density as used to establish the resource at level 1. The benchmarks defined at level 2 are used throughout the resource assessment.
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2.1.3 Level 3 - Technically Accessible Resource Level 3 gives the technical wind resource following removal of low wind speed areas. Low wind speed areas are defined as less than 5m/s at a height of 45m above ground level. 2.1.4 Level 4 - Physically Accessible Level 4 is the physically accessible wind resource after non-accessible areas have been removed, this includes: roads, railways, inland waters, built-up areas, airport, and MoD training sites. The Ordnance Survey Strategi dataset was the base mapping used to develop the various constraint layers used in the resource assessment. Most features found within this dataset are defined by lines. To produce the constraint layers these features require offsets to be built around them to define the in-accessible areas. The offsets used for the various features are defined in Table 2.1. Table 2.1: Feature Offsets Feature
Offset (m)
A roads & primary road
20
B roads
12.5
Motorways
30
Railways
10
Inland waters Lower main river
25
Middle main river
10
Source main river
2.5
Secondary lower
10
Secondary source
2.5
Minor
1.25
Canal
5
Built up areas were identified using the Strategi settlement layer. Active airports were selected from a database of airfields and their perimeters were identified and digitised from
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Google Earth. Ministry of Defence training areas were digitised from the Ordnance Survey 1:50k base mapping. 2.1.5 Level 5 - Practically Accessible Resource (exclusion areas) Level 5 gives the practically viable wind resource after various exclusion areas have been removed. These include; ancient semi-natural woodland and sites of historic interest (Scheduled Ancient Monuments, Listed Buildings, Registered Historic Battlefields, Registered Parks and Gardens and World Heritage Sites) Other exclusion areas were generated by creating offsets from the features listed in level 4. These features and their associated offsets are shown in Table 2.2. Table 2.2:Exclusion Area Offsets Feature
Offset
Roads (Motorway, Primary, A & B)
150m (turbine topple height +10%)
Railway
150m (turbine topple height +10%)
Settlements
600m (mitigation against noise impacts)
Airports
5km (safeguarding mitigation)
Rivers
50m (landowner over sail)
2.1.6 Level 6.1 - Practically Accessible Resource (Environmental Constraints) Level 6.1 gives the practically viable wind resource potential following exclusion of selected environmental designations including: SPAs, SACs, NNRs, SSSIs and Ramsars. 2.1.7 Level 6.2 Practically Accessible Resource (Landscape Constraints) Level 6.2 gives practically viable wind resource following removal of all National Parks, Areas of Outstanding Natural Beauty and Heritage Coast 2.1.8 Level 7 – MOD Consideration The MOD operates a network of air defence radars across the UK. Windfarms have the potential to compromise the operational usefulness of this network and as a result many 42-0336/REN/267 July 2010
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windfarms are refused at planning. To account for this in this wind resource study, a percentage reduction in the overall regional resource was sort from the MoD. 2.1.9 Level 8 – Noise Mitigation Even after all the constraints have been applied to get levels 3 – 6, substantial areas remained. The detailed site finding studies and Environmental Impact Assessments which Wardell Armstrong has undertaken for windfarm developers within the South West have shown that the practically available resource / land area is much smaller. To give a better indication of the wind resource for the South West an additional level has been added. The OS address point dataset gives an accurate location of where amenity space could be compromised by elevated levels of noise. To mitigate against noise impacts, a 600m offset has been placed around each address point. The actual distance required to mitigate noise from large scale turbines will depend on the number of turbines grouped together and their proximity to other sources of noise sources such as roads. Wardell Armstrong’s experience of noise modelling shows that an estimated offset of 600m for this scale of turbine is the minimum requirement in areas with normal background noise levels. 2.2
Small Scale Wind Resource
The small scale resource assessment used the following methodology and benchmarks to establish the required outputs. Buildings were defined as separate locations within the address point database. Identification of these locations effectively removed duplicate entries in the same location, i.e. where flats existed. It was assumed that each building could support a single 6kW turbine. The wind speed used was taken from the NOABL database at the reference height of 10m. The energy curve for a Proven 6kW turbine was used to establish the annual energy production for each turbine using the reference height wind speed. 2.2.1 Level 0 – Natural Resource (no exceptions) Level 0 gives the total natural small scale wind resource assuming that all buildings would be suitable for wind turbines without exception.
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2.2.2 Level 1 – Technically Accessible Resource (wind resource cull) Level 1 gives the technically accessible resource. This is the buildings remaining once those with a wind speed of less than the minimum of 4.5m/s at 10 m above ground level are excluded as defined by the SQW methodology. 2.2.3 Level 2 – Physically Accessible Resource (Built-up area obstruction analysis) Level 2 gives the physically accessible resource by taking into account the reduction in wind speeds experienced in built up areas due to the increased roughness of the ground caused by large numbers of buildings in urban and suburban areas. Based on Ward areas, the resource layer was updated with the Urban / Sub-urban / Rural classification as taken by the DEFRA Rural Definition dataset. The micro generation installed standard given in the SQW methodology shows that depending upon the urban / rural classification, a scaling factor can be applied to the associated wind speeds. The scaling factors are shown in Table 2.3. Table 2.3: Scaling Factors Classification
Scaling Factor
Urban
56%
Sub-urban
67%
Rural
100%
Using the updated rural / urban classification in the wind resource layer, the appropriate scaling factors were applied to the wind speeds at 10m above ground level. In some areas this resulted in the wind speed being below the minimum wind speed threshold of 4.5m/s, at 10m above ground level. Based on the new wind speeds and the energy curve for the Proven 6kW turbine the annual energy output was recalculated. 3
RESULTS
The results for the large scale wind resource have been divided into the different levels described in WA’s and SQW methodology . The wind resource layers associated with each of these levels are available in GIS format. The information has also been tabulated into CSV format and is available by Ward, District, Planning Authority and County. 42-0336/REN/267 July 2010
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3.1
Large Scale Wind Resource
Table 3.1 below shows the regional resource for each level. As the levels progress and more constraints are introduced, the wind resource is reduced. To show the wind resource spread throughout the South West region in more detail, Appendix 1 contains maps which break down the resource for each level based on the Planning Authority boundaries. Each map contains a note which describes the constraints applied to the resource. Table 3.1: Large Scale Wind Resource Wind Average Annual Utilised Installed Number Annual Energy Contribution to Contribution to Resource Wind Speed @ 85m Area Capacity of Production SW electrical SW Total Energy Level AGL for all turbines (km2) (MW) Turbines (MWh/yr) Demand (%) Demand (%) 1 7.1 23857 214710 85884 518968020 1976 396 2 no meaningful results could be extracted from level 2 3 7.1 23790 214109 85644 518325773 1973 396 4 7.1 21367 192306 76923 467794814 1781 357 5 7.2 9416 84747 33899 213791123 814 163 6.1 7.1 8722 78495 31398 195379528 744 149 6.2 6.9 5307 47765 19106 113424668 432 87 7 The MoD have not yet commented on what percentage reduction could be applied 8 7.0 846 7614 3046 17745028 68 14
Carbon Saving (Mt Carbon) 279 278 251 115 105 61 10
Figure 3.1 below shows graphically how the resource varies at each of the levels using the annual energy resource as a measure.
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Figure 3.1: Large Scale Wind Annual Energy Production 3.1.1 Level 1 – Natural Resource The annual energy production for the SW region at level 1 is 518,968GWh/y utilising all the land area without exception. 3.1.2 Level 3 - Technically Accessible Resource The annual energy production for the SW region at level 3 is 518,326GWh/y following removal of low wind speed areas. Low wind speed areas were defined as less than 5m/s at a height of 45m above ground level. This corresponds to a reduction in the resource at level 1 of just 642GWh/y (0.1%)
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3.1.3 Level 4 - Physically Accessible The annual energy production for the SW region at level 4 is 467,795GWh/y following removal of the non-accessible areas. This corresponds to a reduction in the resource from level 3 of 50, 531GWh/y (9.7%) 3.1.4 Level 5 - Practically Accessible Resource (exclusion areas) The annual energy production for the SW region at level 5 is 213,791GWh/y following removal of exclusion areas where practical windfarm development is unlikely. This corresponds to a reduction in the resource from level 4 of 254,004GWh/y (54.2%) 3.1.5 Level 6.1 - Practically Accessible Resource (Environmental Constraints) The annual energy production for the SW region at level 6.1 is 195,380GWh/y following removal of environmentally designated areas. This corresponds to a reduction in the resource from level 5 of 18,411GWh/y (8.6%). 3.1.6 Level 6.2 Practically Accessible Resource (Landscape Constraints) The annual energy production for the SW region at level 6.2 is 113,425GWh/y following removal of landscape designated areas where due to visual impacts windfarm development is less likely to be possible. This corresponds to a reduction in the resource from level 6.1 of 81,955GWh/y (41.9%). 3.1.7 Level 7 – MOD Considerations The annual energy production for the SW region at level 7 cannot be assessed until the MoD produce a percentage reduction scaling factor to take account of the number of sites which are unlikely to be developable due to interference with the air defence radar network. The resource value will be published as an addendum to this report when the scaling factor is released.
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3.1.8 Level 8 – Noise Mitigation Level 8 has been formulated by WA to better estimate the actual potential wind resource following on from the work completed as part of the SQW methodology. The annual energy production for the SW region at level 8 is 17,745GWh/y following removal of areas within a 600m radius of the address point dataset. This corresponds to a reduction in the resource from level 6.2 of 95,680GWh/y (84.4%). 3.2
Small Scale Wind Resource
Table 3.2 below shows the regional resource for each of the three small scale wind resource levels. As the levels progress and more constraints are introduced, the wind resource is reduced. To show the wind resource spread throughout the South West region in more detail, Appendix 2 contains maps which break down the resource for each level based on the Planning Authority boundaries.
Each map contains a note which describes the
constraints applied to the resource. Table 3.2: Small Scale Wind Resource Wind Resource Level
Residentail Address Count
Commercail Address Count
0 1 2
2344515 1871998 375719
121379 89324 16565
Building Count
Number Installed Annual Energy Contribution to Contribution to Carbon of Capacity Production SW electrical SW Total Energy Saving (Mt Turbines (MW) (MWh/yr) Demand (%) Demand (%) Carbon)
2103788 2103788 1684282 1684282 367813 367813
12623 10106 2207
23612004 20408448 4595668
90 78 17
18 16 4
13 11 2
Figure 3.2 below shows graphically how the resource varies at each of the three levels.
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Figure 3.2: Small Scale Wind Annual Energy Production 3.2.1 Level 0 – Natural Resource The annual energy production for the SW region at level 0 is 23,612GWh/y utilising all buildings without exception. This would provide a contribution of 18% of all the SW’s energy requirements. 3.2.2 Level 1 – Technically Accessible Resource The annual energy production for the SW region at level 1 is 20,408GWh/y following removal of low wind speed areas, providing 16% of all the SW’s energy requirements. Low wind speed areas were defined as less than 4.5m/s at a height of 10m above ground level. This corresponds to a reduction in the resource at level 1 of 3204GWh/y (13.6%) 42-0336/REN/267 July 2010
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3.2.3 Level 2 – Technically Accessible Resource The annual energy production for the SW region at level 2 is 4596GWh/y following the wind speed scaling based on the DEFRA rural / urban definition and subsequent removal of buildings due to too low wind speeds. This is 4% of all the SW’s energy requirements and corresponds to a reduction in the resource at level 1 of 15812GWh/y (77.5%) 4
CONCLUSIONS
4.1
Large Commercial Scale Wind Resource
4.1.1 Level 1 – Natural Resource The natural resource shows the energy that could be extracted based solely on land area. Interesting comparisons can be made between the other levels and the natural resource. However the resource values on their own are of no particular interest. 4.1.2 Level 3 - Technically Accessible Resource The technically accessible resource simply involved removal of the low wind speed areas. At a threshold of 5m/s at 45m AGL, only a very small area was actually removed. Low wind speed areas do not produce significant amounts of energy. This therefore meant that there was very little difference between the wind resource at level 1 and 3 (0.1%) 4.1.3 Level 4 - Physically Accessible The physically accessible resource uses the OS Strategi dataset to generate areas which cannot physically be accessed for development of wind farms. These areas include features such as roads, railways and inland water. Although removal of these areas did result in a significant reduction of the resource (9.7%), it is likely that use of OS 1:50k Vector Map instead of Strategi 1:250K would have resulted in a much greater reduction in the resource. In addition to the use of these datasets, OS Address Point could have been used to identify those areas occupied by buildings.
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4.1.4 Level 5 - Practically Accessible Resource (exclusion areas) Level 5 sees the largest percentage reduction in wind resource when following the SQW methodology (54.2%). However, the reduction would have been much greater if the more detailed vector map dataset had been used to generate the exclusion areas discussed in level 4. It would also have been prudent to use 600m offsets generated from the OS Address Point dataset (See level 8) 4.1.5 Level 6.1 & 6.2 - Practically Accessible Resource (Environmental and Lanscape Constraints) The practically accessible resource takes account of both environmental and landscape designations at levels 6.1 and 6.2. These were divided in two to examine the effects of each independently.
Once the constraints of the previous levels had been applied,
environmental designation constraints lead to a reduction of 8.6% of the resource available at level 5. A further 41.9% reduction in the wind resource resulted from removal of the landscape designated areas. This is primarily due to the majority of landscape designations being located on moors or next to the coast which often also have the highest wind resource. 4.1.6 Level 7 – MOD Considerations No conclusions can be drawn at this level until further information on wind resource scaling based on MoD impacts has been received. 4.1.7 Level 8 – Noise Mitigation Level 8 does not form part of the original SQW methodology but has produced a significant reduction in the available wind resource (84.4%). There is no reason for this not to be used as a constraint to large scale wind resource as even a single 2.5MW turbine would have to be placed at least 600m from residential properties. It would however be more suitably applied at level 5 as identified in 4.1.4.
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4.2
Small Scale Wind Resource
4.2.1 Level 0 – Natural Resource The natural resource shows the energy that could be extracted based solely on the numbers of buildings present within the area. Interesting comparisons can be made between the different levels and the natural resource, however the resource values on their own are of no particular interest. 4.2.2 Level 1 - Technically Accessible Resource The technically accessible resource simply involved removal of the low wind speed areas, which translated to a 13.6% reduction in the resource from level 0. In comparison to the large scale wind resource this step is much larger and has probably resulted from the fact that the most densely populated areas with the most buildings tend to be in lower wind speed areas falling below the minimum wind speed threshold. 4.2.3 Level 2 - Technically Accessible Resource Level 2 gives the physically accessible resource by taking into account the reduction in wind speeds experienced in built up areas. This resulted in a 77.5% decrease in the wind resource. It is important to recognise that the wind resource at this level is a considerable over estimate of what could actually technically be achieved. It has been suggested recently that turbines of this scale are not particularly suitable for roof mounted installation and should be located at least 150m from schools and houses. This information is derived from a turbine manufacturer, Proven, who recently experienced potentially dangerous failures to some of their installed turbines. A more realistic turbine size might be a 1.5kW turbine which has a significantly different energy curve and therefore the annually energy output would be significantly lower. The technically accessible resource does not account for any of the practically accessible constraints which are considered as part of the large scale wind resource methodology.
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5
RECOMMENDATIONS
5.1
Large Scale Wind Resource
It is recommended that for examination of large commercial scale wind resource, level 8 is used as this gives the resource most likely to be developable. The remaining resource potential at this level would also be subject to the following considerations;
5.2
MoD radars
Civil radars
Visual impact outside of landscape designations
Setting (proximity to scheduled monuments and listed buildings)
Shadow flicker
Small Scale Wind Resource
It is recommended that the small scale wind resource be re-assessed with an energy curve for a 1.5kW turbine in place of the 6kW turbine. Further levels could be added to help better define the available wind resource. WA would suggest two addition resource levels: Socially Acceptable Small Scale Wind Resource and Economically Acceptable Small Scale Wind Resource. The Socially Acceptable level would minimise the cumulative impact of noise for adjacent buildings. This would be implemented by limiting development to only one turbine within a 50m radius. The economically acceptable level would take account of affordability of the turbines and suitability of properties. This would be implemented by excluding all properties which fall within the council tax band A.
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CONTENTS 1
INTRODUCTION......................................................................................................................... 1
2
METHODOLOGY ........................................................................................................................ 1
3
4
5
2.1
Large Scale Wind Resource................................................................................................. 1
2.2
Small Scale Wind Resource................................................................................................. 5
RESULTS .................................................................................................................................... 6 3.1
Large Scale Wind Resource................................................................................................. 7
3.2
Small Scale Wind Resource............................................................................................... 10
CONCLUSIONS ......................................................................................................................... 12 4.1
Large Commercial Scale Wind Resource ........................................................................... 12
4.2
Small Scale Wind Resource............................................................................................... 14
RECOMMENDATIONS.............................................................................................................. 15 5.1
Large Scale Wind Resource............................................................................................... 15
5.2
Small Scale Wind Resource............................................................................................... 15
TABLES Table 2.1: Feature Offsets.................................................................................................................. 3 Table 2.2:Exclusion Area Offsets ........................................................................................................ 4 Table 2.3: Scaling Factors................................................................................................................... 6 Table 3.1: Large Scale Wind Resource ................................................................................................ 7 Table 3.2: Small Scale Wind Resource .............................................................................................. 10
FIGURES Figure 3.1: Large Scale Wind Annual Energy Production..................................................................... 8 Figure 3.2: Small Scale Wind Annual Energy Production................................................................... 11
APPENDICES Appendix 1: Local Authority Large Scale Wind Resource Level Maps Appendix 2: Local Authority Small Scale Wind Resource Level Maps 42-0336/REN/267 July 2010
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1
INTRODUCTION
This report details the methodology used to update the South West wind resource assessment originally undertaken as part of the Renewable Energy Atlas and Revision 2020 projects completed in 2006. This re-assessment of the wind resource has followed guidance from the SQWenergy report entitled “Renewable and Low-carbon Energy Capacity Methodology – Methodology for the English Regions” issued by DECC in January 2010. 2
METHODOLOGY
The methodology is divided into two sections which detail how the resource for the large and small resource assessments have been undertaken. The resource assessment for each scale was started from a layer comprised of the South West boundary clipped to the high tide line. The polygon was then split by the NOABL wind speed one kilometre grid and ward boundaries. The wind speeds at 85m and 10m, Ward names, District names, Local Planning Authority and County names were saved as attribute fields to each of the split polygons. The potential wind resource is expressed in four different features:
Energy (GWh/yr or MWh/yr)
Percentage contribution to the South West regions annual electricity demand (26267GWh/y)
Percentage contribution to the South West regions total annual consumption (130920GWh/y) - Electricity and total energy consumption figures were taken from DECC’s 2007 report.
The carbon saving (0.537kg of carbon / kilowatt hour of electricity produced DEFRA).
2.1
Large Scale Wind Resource
The resource assessment for large scale wind used the following methodology and benchmarks to establish the values described above. A wind speed up log law calculation was used to estimate the wind speed at 85m above ground level from the 45m reference height in the NOABL database.
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A surface roughness value of 0.03 was used in the
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calculation. The resultant speed up factor applied to the 45m wind speed values to derive the wind speed at 85m was 1.087. The installed generating capacity was estimated based on land area within each ward, district, planning authority and county boundary. This was based on the benchmark figure of 9MW/km2 from the SQW methodology. The number of turbines for each area was back calculated from the installed capacity by dividing it by 2.5MW, the turbine capacity suggested in the SQW methodology. A Nordex N80 2.5MW turbine was subsequently used as the reference turbine for energy calculations, etc.
This turbine is representative of the scale of turbine used in large commercial
windfarms. Each discrete area falls within a specific 1km grid square with an identified wind speed at a reference height of 85m. The total number of turbines within these discrete areas was then used as a multiplier on the annual energy output for a single N80 Nordex turbine derived from its energy curve at the given wind speed. The SQW methodology identifies several resource levels for large commercial scale wind turbines. Cumulatively each level further constrains the resource. Each level is detailed below. 2.1.1 Level 1 – Natural Resource Level 1 gives the total natural wind resource, utilising all the land within the South West without exception. 2.1.2 Level 2 - Benchmark Figures No meaningful output could be achieved at level 2 as this simply defines the turbine capacity and the packing density as used to establish the resource at level 1. The benchmarks defined at level 2 are used throughout the resource assessment.
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2.1.3 Level 3 - Technically Accessible Resource Level 3 gives the technical wind resource following removal of low wind speed areas. Low wind speed areas are defined as less than 5m/s at a height of 45m above ground level. 2.1.4 Level 4 - Physically Accessible Level 4 is the physically accessible wind resource after non-accessible areas have been removed, this includes: roads, railways, inland waters, built-up areas, airport, and MoD training sites. The Ordnance Survey Strategi dataset was the base mapping used to develop the various constraint layers used in the resource assessment. Most features found within this dataset are defined by lines. To produce the constraint layers these features require offsets to be built around them to define the in-accessible areas. The offsets used for the various features are defined in Table 2.1. Table 2.1: Feature Offsets Feature
Offset (m)
A roads & primary road
20
B roads
12.5
Motorways
30
Railways
10
Inland waters Lower main river
25
Middle main river
10
Source main river
2.5
Secondary lower
10
Secondary source
2.5
Minor
1.25
Canal
5
Built up areas were identified using the Strategi settlement layer. Active airports were selected from a database of airfields and their perimeters were identified and digitised from
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Google Earth. Ministry of Defence training areas were digitised from the Ordnance Survey 1:50k base mapping. 2.1.5 Level 5 - Practically Accessible Resource (exclusion areas) Level 5 gives the practically viable wind resource after various exclusion areas have been removed. These include; ancient semi-natural woodland and sites of historic interest (Scheduled Ancient Monuments, Listed Buildings, Registered Historic Battlefields, Registered Parks and Gardens and World Heritage Sites) Other exclusion areas were generated by creating offsets from the features listed in level 4. These features and their associated offsets are shown in Table 2.2. Table 2.2:Exclusion Area Offsets Feature
Offset
Roads (Motorway, Primary, A & B)
150m (turbine topple height +10%)
Railway
150m (turbine topple height +10%)
Settlements
600m (mitigation against noise impacts)
Airports
5km (safeguarding mitigation)
Rivers
50m (landowner over sail)
2.1.6 Level 6.1 - Practically Accessible Resource (Environmental Constraints) Level 6.1 gives the practically viable wind resource potential following exclusion of selected environmental designations including: SPAs, SACs, NNRs, SSSIs and Ramsars. 2.1.7 Level 6.2 Practically Accessible Resource (Landscape Constraints) Level 6.2 gives practically viable wind resource following removal of all National Parks, Areas of Outstanding Natural Beauty and Heritage Coast 2.1.8 Level 7 – MOD Consideration The MOD operates a network of air defence radars across the UK. Windfarms have the potential to compromise the operational usefulness of this network and as a result many 42-0336/REN/267 July 2010
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windfarms are refused at planning. To account for this in this wind resource study, a percentage reduction in the overall regional resource was sort from the MoD. 2.1.9 Level 8 – Noise Mitigation Even after all the constraints have been applied to get levels 3 – 6, substantial areas remained. The detailed site finding studies and Environmental Impact Assessments which Wardell Armstrong has undertaken for windfarm developers within the South West have shown that the practically available resource / land area is much smaller. To give a better indication of the wind resource for the South West an additional level has been added. The OS address point dataset gives an accurate location of where amenity space could be compromised by elevated levels of noise. To mitigate against noise impacts, a 600m offset has been placed around each address point. The actual distance required to mitigate noise from large scale turbines will depend on the number of turbines grouped together and their proximity to other sources of noise sources such as roads. Wardell Armstrong’s experience of noise modelling shows that an estimated offset of 600m for this scale of turbine is the minimum requirement in areas with normal background noise levels. 2.2
Small Scale Wind Resource
The small scale resource assessment used the following methodology and benchmarks to establish the required outputs. Buildings were defined as separate locations within the address point database. Identification of these locations effectively removed duplicate entries in the same location, i.e. where flats existed. It was assumed that each building could support a single 6kW turbine. The wind speed used was taken from the NOABL database at the reference height of 10m. The energy curve for a Proven 6kW turbine was used to establish the annual energy production for each turbine using the reference height wind speed. 2.2.1 Level 0 – Natural Resource (no exceptions) Level 0 gives the total natural small scale wind resource assuming that all buildings would be suitable for wind turbines without exception.
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2.2.2 Level 1 – Technically Accessible Resource (wind resource cull) Level 1 gives the technically accessible resource. This is the buildings remaining once those with a wind speed of less than the minimum of 4.5m/s at 10 m above ground level are excluded as defined by the SQW methodology. 2.2.3 Level 2 – Physically Accessible Resource (Built-up area obstruction analysis) Level 2 gives the physically accessible resource by taking into account the reduction in wind speeds experienced in built up areas due to the increased roughness of the ground caused by large numbers of buildings in urban and suburban areas. Based on Ward areas, the resource layer was updated with the Urban / Sub-urban / Rural classification as taken by the DEFRA Rural Definition dataset. The micro generation installed standard given in the SQW methodology shows that depending upon the urban / rural classification, a scaling factor can be applied to the associated wind speeds. The scaling factors are shown in Table 2.3. Table 2.3: Scaling Factors Classification
Scaling Factor
Urban
56%
Sub-urban
67%
Rural
100%
Using the updated rural / urban classification in the wind resource layer, the appropriate scaling factors were applied to the wind speeds at 10m above ground level. In some areas this resulted in the wind speed being below the minimum wind speed threshold of 4.5m/s, at 10m above ground level. Based on the new wind speeds and the energy curve for the Proven 6kW turbine the annual energy output was recalculated. 3
RESULTS
The results for the large scale wind resource have been divided into the different levels described in WA’s and SQW methodology . The wind resource layers associated with each of these levels are available in GIS format. The information has also been tabulated into CSV format and is available by Ward, District, Planning Authority and County. 42-0336/REN/267 July 2010
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3.1
Large Scale Wind Resource
Table 3.1 below shows the regional resource for each level. As the levels progress and more constraints are introduced, the wind resource is reduced. To show the wind resource spread throughout the South West region in more detail, Appendix 1 contains maps which break down the resource for each level based on the Planning Authority boundaries. Each map contains a note which describes the constraints applied to the resource. Table 3.1: Large Scale Wind Resource Wind Average Annual Utilised Installed Number Annual Energy Contribution to Contribution to Resource Wind Speed @ 85m Area Capacity of Production SW electrical SW Total Energy Level AGL for all turbines (km2) (MW) Turbines (MWh/yr) Demand (%) Demand (%) 1 7.1 23857 214710 85884 518968020 1976 396 2 no meaningful results could be extracted from level 2 3 7.1 23790 214109 85644 518325773 1973 396 4 7.1 21367 192306 76923 467794814 1781 357 5 7.2 9416 84747 33899 213791123 814 163 6.1 7.1 8722 78495 31398 195379528 744 149 6.2 6.9 5307 47765 19106 113424668 432 87 7 The MoD have not yet commented on what percentage reduction could be applied 8 7.0 846 7614 3046 17745028 68 14
Carbon Saving (Mt Carbon) 279 278 251 115 105 61 10
Figure 3.1 below shows graphically how the resource varies at each of the levels using the annual energy resource as a measure.
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Figure 3.1: Large Scale Wind Annual Energy Production 3.1.1 Level 1 – Natural Resource The annual energy production for the SW region at level 1 is 518,968GWh/y utilising all the land area without exception. 3.1.2 Level 3 - Technically Accessible Resource The annual energy production for the SW region at level 3 is 518,326GWh/y following removal of low wind speed areas. Low wind speed areas were defined as less than 5m/s at a height of 45m above ground level. This corresponds to a reduction in the resource at level 1 of just 642GWh/y (0.1%)
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3.1.3 Level 4 - Physically Accessible The annual energy production for the SW region at level 4 is 467,795GWh/y following removal of the non-accessible areas. This corresponds to a reduction in the resource from level 3 of 50, 531GWh/y (9.7%) 3.1.4 Level 5 - Practically Accessible Resource (exclusion areas) The annual energy production for the SW region at level 5 is 213,791GWh/y following removal of exclusion areas where practical windfarm development is unlikely. This corresponds to a reduction in the resource from level 4 of 254,004GWh/y (54.2%) 3.1.5 Level 6.1 - Practically Accessible Resource (Environmental Constraints) The annual energy production for the SW region at level 6.1 is 195,380GWh/y following removal of environmentally designated areas. This corresponds to a reduction in the resource from level 5 of 18,411GWh/y (8.6%). 3.1.6 Level 6.2 Practically Accessible Resource (Landscape Constraints) The annual energy production for the SW region at level 6.2 is 113,425GWh/y following removal of landscape designated areas where due to visual impacts windfarm development is less likely to be possible. This corresponds to a reduction in the resource from level 6.1 of 81,955GWh/y (41.9%). 3.1.7 Level 7 – MOD Considerations The annual energy production for the SW region at level 7 cannot be assessed until the MoD produce a percentage reduction scaling factor to take account of the number of sites which are unlikely to be developable due to interference with the air defence radar network. The resource value will be published as an addendum to this report when the scaling factor is released.
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3.1.8 Level 8 – Noise Mitigation Level 8 has been formulated by WA to better estimate the actual potential wind resource following on from the work completed as part of the SQW methodology. The annual energy production for the SW region at level 8 is 17,745GWh/y following removal of areas within a 600m radius of the address point dataset. This corresponds to a reduction in the resource from level 6.2 of 95,680GWh/y (84.4%). 3.2
Small Scale Wind Resource
Table 3.2 below shows the regional resource for each of the three small scale wind resource levels. As the levels progress and more constraints are introduced, the wind resource is reduced. To show the wind resource spread throughout the South West region in more detail, Appendix 2 contains maps which break down the resource for each level based on the Planning Authority boundaries.
Each map contains a note which describes the
constraints applied to the resource. Table 3.2: Small Scale Wind Resource Wind Resource Level
Residentail Address Count
Commercail Address Count
0 1 2
2344515 1871998 375719
121379 89324 16565
Building Count
Number Installed Annual Energy Contribution to Contribution to Carbon of Capacity Production SW electrical SW Total Energy Saving (Mt Turbines (MW) (MWh/yr) Demand (%) Demand (%) Carbon)
2103788 2103788 1684282 1684282 367813 367813
12623 10106 2207
23612004 20408448 4595668
90 78 17
18 16 4
13 11 2
Figure 3.2 below shows graphically how the resource varies at each of the three levels.
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Figure 3.2: Small Scale Wind Annual Energy Production 3.2.1 Level 0 – Natural Resource The annual energy production for the SW region at level 0 is 23,612GWh/y utilising all buildings without exception. This would provide a contribution of 18% of all the SW’s energy requirements. 3.2.2 Level 1 – Technically Accessible Resource The annual energy production for the SW region at level 1 is 20,408GWh/y following removal of low wind speed areas, providing 16% of all the SW’s energy requirements. Low wind speed areas were defined as less than 4.5m/s at a height of 10m above ground level. This corresponds to a reduction in the resource at level 1 of 3204GWh/y (13.6%) 42-0336/REN/267 July 2010
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3.2.3 Level 2 – Technically Accessible Resource The annual energy production for the SW region at level 2 is 4596GWh/y following the wind speed scaling based on the DEFRA rural / urban definition and subsequent removal of buildings due to too low wind speeds. This is 4% of all the SW’s energy requirements and corresponds to a reduction in the resource at level 1 of 15812GWh/y (77.5%) 4
CONCLUSIONS
4.1
Large Commercial Scale Wind Resource
4.1.1 Level 1 – Natural Resource The natural resource shows the energy that could be extracted based solely on land area. Interesting comparisons can be made between the other levels and the natural resource. However the resource values on their own are of no particular interest. 4.1.2 Level 3 - Technically Accessible Resource The technically accessible resource simply involved removal of the low wind speed areas. At a threshold of 5m/s at 45m AGL, only a very small area was actually removed. Low wind speed areas do not produce significant amounts of energy. This therefore meant that there was very little difference between the wind resource at level 1 and 3 (0.1%) 4.1.3 Level 4 - Physically Accessible The physically accessible resource uses the OS Strategi dataset to generate areas which cannot physically be accessed for development of wind farms. These areas include features such as roads, railways and inland water. Although removal of these areas did result in a significant reduction of the resource (9.7%), it is likely that use of OS 1:50k Vector Map instead of Strategi 1:250K would have resulted in a much greater reduction in the resource. In addition to the use of these datasets, OS Address Point could have been used to identify those areas occupied by buildings.
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4.1.4 Level 5 - Practically Accessible Resource (exclusion areas) Level 5 sees the largest percentage reduction in wind resource when following the SQW methodology (54.2%). However, the reduction would have been much greater if the more detailed vector map dataset had been used to generate the exclusion areas discussed in level 4. It would also have been prudent to use 600m offsets generated from the OS Address Point dataset (See level 8) 4.1.5 Level 6.1 & 6.2 - Practically Accessible Resource (Environmental and Lanscape Constraints) The practically accessible resource takes account of both environmental and landscape designations at levels 6.1 and 6.2. These were divided in two to examine the effects of each independently.
Once the constraints of the previous levels had been applied,
environmental designation constraints lead to a reduction of 8.6% of the resource available at level 5. A further 41.9% reduction in the wind resource resulted from removal of the landscape designated areas. This is primarily due to the majority of landscape designations being located on moors or next to the coast which often also have the highest wind resource. 4.1.6 Level 7 – MOD Considerations No conclusions can be drawn at this level until further information on wind resource scaling based on MoD impacts has been received. 4.1.7 Level 8 – Noise Mitigation Level 8 does not form part of the original SQW methodology but has produced a significant reduction in the available wind resource (84.4%). There is no reason for this not to be used as a constraint to large scale wind resource as even a single 2.5MW turbine would have to be placed at least 600m from residential properties. It would however be more suitably applied at level 5 as identified in 4.1.4.
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4.2
Small Scale Wind Resource
4.2.1 Level 0 – Natural Resource The natural resource shows the energy that could be extracted based solely on the numbers of buildings present within the area. Interesting comparisons can be made between the different levels and the natural resource, however the resource values on their own are of no particular interest. 4.2.2 Level 1 - Technically Accessible Resource The technically accessible resource simply involved removal of the low wind speed areas, which translated to a 13.6% reduction in the resource from level 0. In comparison to the large scale wind resource this step is much larger and has probably resulted from the fact that the most densely populated areas with the most buildings tend to be in lower wind speed areas falling below the minimum wind speed threshold. 4.2.3 Level 2 - Technically Accessible Resource Level 2 gives the physically accessible resource by taking into account the reduction in wind speeds experienced in built up areas. This resulted in a 77.5% decrease in the wind resource. It is important to recognise that the wind resource at this level is a considerable over estimate of what could actually technically be achieved. It has been suggested recently that turbines of this scale are not particularly suitable for roof mounted installation and should be located at least 150m from schools and houses. This information is derived from a turbine manufacturer, Proven, who recently experienced potentially dangerous failures to some of their installed turbines. A more realistic turbine size might be a 1.5kW turbine which has a significantly different energy curve and therefore the annually energy output would be significantly lower. The technically accessible resource does not account for any of the practically accessible constraints which are considered as part of the large scale wind resource methodology.
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5
RECOMMENDATIONS
5.1
Large Scale Wind Resource
It is recommended that for examination of large commercial scale wind resource, level 8 is used as this gives the resource most likely to be developable. The remaining resource potential at this level would also be subject to the following considerations;
5.2
MoD radars
Civil radars
Visual impact outside of landscape designations
Setting (proximity to scheduled monuments and listed buildings)
Shadow flicker
Small Scale Wind Resource
It is recommended that the small scale wind resource be re-assessed with an energy curve for a 1.5kW turbine in place of the 6kW turbine. Further levels could be added to help better define the available wind resource. WA would suggest two addition resource levels: Socially Acceptable Small Scale Wind Resource and Economically Acceptable Small Scale Wind Resource. The Socially Acceptable level would minimise the cumulative impact of noise for adjacent buildings. This would be implemented by limiting development to only one turbine within a 50m radius. The economically acceptable level would take account of affordability of the turbines and suitability of properties. This would be implemented by excluding all properties which fall within the council tax band A.
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