BATSWORTHY CROSS WIND FARM
ENVIRONMENTAL STATEMENT
Table of Contents
13.
13.1.
13.2.
13.3.
13.3.1.
13.3.2.
13.3.3.
13.3.4.
13.4.
13.4.1.
13.4.2.
13.4.3.
13.4.4.
13.5.
13.5.1.
Electro-Magnetic Interference & Communication Links
Introduction
Summary
Methodology
Policy Considerations
Television and Radio Reception
Mobile Phone and Other Fixed Communication Links
Aviation and Defence
Assessment of Potential Impacts
Domestic Television Reception
Television Infrastructure
Microwave Fixed Links
Aviation and Defence
Mitigation
Domestic Television Reception
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496
496
497
497
498
498
499
499
499
500
500
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13.6.
Conclusions
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13. Electro-Magnetic Interference & Communication Links
13.1. Introduction
The Electro-Magnetic Interference (EMI) and Communication Link survey seeks to
establish if there are any potential affects on existing infrastructure. This is conducted
through consultation with all the relevant system operators. This consultation process
and results are described below. The proposal has received approval from all the
consultees.
Wind turbines are not directly subject to the Communications Act 2003 and require no
authorisation from Ofcom in their management of the radio spectrum and granting
licences under the Wireless Telegraphy Act. However, planning authorities do consider
the potential impact of structures on existing infrastructure and they generally require
that consideration of such impacts is made by wind energy developers.
Interference can arise when wind turbines interact with electromagnetic transmissions,
resulting in changes to the received signal and so in the use of that signal by the user.
Radio waves and microwaves are used in a variety of communications and any large
structure has the potential to interfere with their reception. The magnitude of the affect
of a structure is principally dependent upon the size, shape and materials of
construction. Wind turbines are both very slender and the rotor is substantially
constructed from non-conducting materials (Glass Reinforced Plastic), both of which
reduce their potential for causing interference. However, the tower is usually steel and
the rotor blades contain some conductive materials, for lightning conduction and in
some cases structural carbon fibre. The blade movement may also have an affect on
aviation radar which are designed to detect movement.
The potential affects on electromagnetic signals are highly dependent on the location of
the wind farm and on the positions of the individual turbines. In some cases there are
no significant consequences and no mitigation is required, whilst in other cases the
turbine specification or layout must be designed to accommodate local infrastructure. In
the extreme, sites can be considered inappropriate for wind energy development.
The key sensitivities are the potential affects on civil and defence aviation radar,
microwave communications and television broadcasting and reception. The EMI survey
addresses all these elements to determine the suitability of the site and any mitigation
measures required to overcome potential affects. The EMI assessment is conducted
through consultation with the operators of these systems.
13.2. Summary
The table below provides a summary of the situation for each organisation consulted
within this EMI survey.
Organisation
Ministry of
Defence
Interest
Defence
Civil Aviation
Authority
(DAP)
Physical
obstruction of
aviation
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Consulted
3
3
Status
No objection;
confirmed by letter
from MOD
safeguarding team
dated January 7th
2004
No objection;
confirmed by letter
dated August 14th
Mitigation
Not required
Not required
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2004.
NERL do not provide
any pre-planning
response.
3
Ofcom
Affects on enroute radar for Air
Traffic Control
and navaids.
Fixed links
3
BT, T-Mobile and MLL
links identified; email
response received
September 9th 2005.
Orange
Fixed links
3
BT
Fixed links
3
T-mobile
Fixed links
3
Cable &
Wireless
Fixed links
3
MLL Telecom
Fixed links
3
CSS
Fixed links
3
JRC
Fixed links
3
Arqiva
(formerly ntl)
TV re-broadcast
links and fixed
links
3
No objection;
confirmed by email
January 4th 2006.
No objection;
confirmed by email
October 10th 2005.
No objection;
confirmed by email
October 12th 2005.
No objection;
confirmed by email
September 9th 2005.
No objection;
confirmed by email
September 30th 2005.
No objection;
confirmed by email
October 3rd 2005.
No objection;
confirmed by email
October 12th 2005.
No objection
confirmed by email
October 12th 2005.
Crown Castle
TV re-broadcast
links and fixed
links
Domestic
television
reception
3
NATS
en-route
(NERL)
BBC
3
Via web-site
tool
No objection;
confirmed by email
September 27th 2005.
Slight risk of
interference for
individual properties;
automated response
by email dated
September 27th 2005.
n/a
Direct
consultation
with link
operators, see
below.
Not required
Not required
Not required
Not required
Not required
Not required
Not required
Not required
Not required
Post build
mitigation for
households
affected
13.3. Methodology
13.3.1. Policy Considerations
The most relevant planning policy guidance in relation to Electro-Magnetic Interference
is contained within PPS22. PPG8 on Telecommunications advises on the potential for
disturbance to television and other telecommunications signals and the need to
investigate possible engineering solutions to such matters.
PPS22 – Renewable Energy
Section 25 on wind turbines states, “Regional spatial strategies should not include
specific policies relating to the impact of wind turbines on airport operation, radar and
aircraft, and neither they nor local development documents should include policies in
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relation to separation distances from power lines, roads, and railways. It is the
responsibility of developers to address any potential impacts, taking account of Civil
Aviation Authority, Ministry of Defence and Department for Transport guidance in
relation to radar and aviation, and the legislative requirements on separation distances,
before planning applications are submitted. Local Planning Authorities should satisfy
themselves that such issues have been addressed before considering planning
applications.”
PPG8 - Telecommunications
This PPG, which is effective from 22 August 2001, gives guidance on planning for
telecommunications development including radio masts and towers, antennas of all
kinds, radio equipment housing, public call boxes, cabinets, poles and overhead wires.
Under other development, paragraph 33 states “The construction of new buildings or
other structures, such as wind turbines, can interfere with broadcast and other
telecommunications services, and the possibility of such interference can be a material
planning consideration”.
13.3.2. Television and Radio Reception
Terrestrial television services within the UK are the joint responsibility of the BBC and
the Office of Communications (Ofcom). The transmission network is provided and
operated on behalf of the broadcasters’ by National Grid Wireless (Crown Castle) and
Arqiva (formerly NTL).
To slip-stream the consultation process for wind farms the BBC and Ofcom have
provided a web-based assessment tool for use by wind developers
(http://windfarms.kw.bbc.co.uk/). This replaces written consultation in respect of
domestic television and radio interference.
Television programme distribution is provided through a network of transmitters, rebroadcast links (RBLs) and microwave links. Both microwave links and RBLs can be
affected at any point along their path, which can be up to 70 km long. Written
consultation is still required for the network operators National Grid Wireless (Crown
Castle) and Arqiva.
The BBC, the ITC and the Radiocommunications Agency (now under Ofcom) have
jointly produced a technical note titled ‘The impact of large buildings and structures
(including wind farms) on Terrestrial Television Reception’, describing the mechanisms
that create television reception problems and measures that can be taken to minimise
the affects.
13.3.3. Mobile Phone and Other Fixed Communication Links
Interference with mobile phone reception and other wireless data networks can occur
through disruption of microwave fixed links. These are operated by or on the behalf of
the mobile service providers, the utility companies, the emergency services and some
small private networks. Ofcom holds a database of licensed links and manages the
allocation of frequencies. When consulted Ofcom use their database to determine the
presence of any fixed links in the area of proposed developments including wind farms.
A number of network operators have exclusive use of part of the microwave spectrum of
frequencies and can plan or install links in advance of informing Ofcom. In addition to
Ofcom it is essential to consult with Crown Castle, NTL, BT, Cable and Wireless,
Orange, T-Mobile, JRC and CSS.
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13.3.4. Aviation and Defence
Wind turbines can have an effect on flying simply by virtue of their physical presence.
In this respect they are no different to any other tall obstacles such as pylons or
television masts. Such obstacles are a normal part of the aviation scenery and
measures are in place to enable aircraft to safely navigate around them.
Wind turbines also have the potential to affect the provision of air traffic services (ATS)
through several different mechanisms, depending upon the specific equipment being
used. The most common cause for concern is their potential effect on Primary
Surveillance Radar (PSR). These radars are used by many aerodromes and by
National Air Traffic Services (NATS) En-Route Limited (NERL). Aerodromes use PSR
to monitor and control air traffic in their area. NERL provide radar based services to
control high altitude air traffic across the entire national airspace.
Radars are also used by the Met Office to monitor the weather. There are 12 weather
radar stations in the UK, safeguarded by the Ministry of Defence (MOD).
The Consultation Process
A ‘Wind Farm Developers Application Proforma’ was submitted to The Directorate of
Airspace Policy and the MOD Safeguarding Department at Defence Estates. This form
is automatically passed to the Civil Aviation Authority (CAA) Safety Regulation Group
and NERL, covering all defence and aviation interests. The MOD, NERL and the CAA
are all statutory consultees.
The Directorate of Airspace Policy (DAP) responds to pre-planning consultations by
informing the developer of any airfields/airports that should be consulted directly. It is
then the joint responsibility of the developer and the airfield to consider the potential
impacts and mitigation measures required to enable the development. The DAP will
also highlight any lighting requirements.
NERL have withdrawn their pre-planning consultation service. They have generated a
number of maps designed to provide developers with basic information about the areas
where wind turbine developments maybe of concern to them. These maps are provided
for guidance only and do not affect the consultation requirements for formal planning
applications set out in The Town and Country Planning (Safeguarded Aerodromes,
Technical Sites and Military Explosive Storage Areas) Direction 2002.
Defence Estates respond on behalf of all defence interests covering the army, navy,
RAF and Met Office.
13.4. Assessment of Potential Impacts
13.4.1. Domestic Television Reception
Domestic television interference, affecting the signal between the transmitter and the
television aerial, can be affected up to a maximum distance of approximately 5km from
a wind turbine in the case of weak signal and a strong reflection from a structure.
The BBC’s wind farm assessment tool was interrogated to determine the potential scale
of domestic television interference. The results indicated that 47 homes with no
alternative transmitter to tune to may be affected and a further 109 that may be able to
tune to an alternative transmitter. Tuning to an alternative transmitter involves rotating
the aerial to align with this alternative transmitter.
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13.4.2. Television Infrastructure
The television network operators Crown Castle and Arqiva have been consulted and
have responded with no objection to the proposed wind farm at Batsworthy Cross.
13.4.3. Microwave Fixed Links
A number of fixed links do run in the proximity of the site; operated by BT, T-Mobile and
MLL telecom. The links radiate from the Meshaw mast, grid reference SS792195 and
details of these links are shown in Figure 13.1. The links all pass to the west of the site
with sufficient clearance from the proposed turbines to be unaffected by them.
BT, T-Mobile and MLL telecom have all been consulted against the detailed turbine
layout and have responded with no objections.
13.4.4. Aviation and Defence
No objection or comment was raised by either the DAP or the MOD. This provides
clearance covering for all defence interests and CAA interests.
NERL no longer respond in advance of planning applications, but there is a strong
indication that they will have no objection. There are no lower airspace air traffic service
routes over the wind farm. The site does not lie in an important part of UK airspace and
NERL are likely to be using SSR in the area to control en-route traffic. Secondary
Surveilance Radar (SSR) should not be affected by the proposed wind farm. The
nearest SSR is at Burrington 21km to the west of the site.
Three other wind farms in the locality have not had objections from NERL. These are
Higher Daracott, near Great Torrington in Devon which has received planning approval,
Forest Moor, near Bradworthy in Devon which has also received planning approval and
West Hinkley, at Hinkly Point in Devon which was rejected on power station safety
concerns but received no objection from NERL.
13.5. Mitigation
13.5.1. Domestic Television Reception
The response from the BBC wind farms tool indicates some potential for interference to
domestic television reception. The numbers provided indicate the maximum possible
extent of the issue.
By its nature, it is not possible to reliably predict the extent to which problems will
actually be realised. It may be that the numbers of properties affected is of a much
lower scale than the ‘potential’ scale identified by the BBC tool. For this reason it is not
appropriate to implement mitigation in advance of turbine installation; with any required
mitigation then being targeted at those specific properties affected.
There are a number of post build mitigation options to address any interference that
does become apparent. For the majority of the potentially affected properties (109 out of
156) the solution may be as simple as re-aligning (rotating) individual aerials to receive
their signal from an alternative transmitter (off-air). Where this does not prove sufficient,
aerials can also be re-sited or upgraded to improve reception. Up to 47 properties may
not have the possibility of re-aligning their aerials to receive an alternative transmission
signal. Once again any problems that arise with these properties may be resolved
through re-siting or upgrading aerials. Alternatively television reception could be
provided from cable or satellite. In some cases it is feasible to install a local receiving
aerial to provide a clean signal via cable to a local group of affected households.
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Where a wind development does cause reception problems, the BBC and Ofcom look
to the developer to rectify these. An appropriately worded planning condition is typically
used to enforce this.
13.6. Conclusions
All appropriate parties have been consulted and responded. Any potential impacts have
been considered in detail and addressed. There are no concerns over impacts on
defence interests, CAA interests, fixed link operators or the television transmission
network.
There remains a possibility of some impact on domestic television reception. Because
of the small scale of this issue and the difficulty in predicting outcomes, it is considered
appropriate to adopt the normal practice of addressing any actual impacts once the
wind farm has been built though an appropriately worded planning condition.
Please refer to Volume 2 for the following figure:
Chapter
13
Title
Electro-Magnetic Interference and
Communication Links
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Figure
13.1
Title
Fixed Communications Links
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