Wind Farming Essentials Presentation to the Forestry
Engineering Group Symposium
Dr. Conrad Trevelyan
Wind Farming Essentials
September 2009
•Mech.Eng (Brighton), MSc Renewable
Energy Technology (CREST) and
completed doctorate 2002 (wind turbine
aerodynamics)
•Now a Senior Project Manager at Dulas
Ltd (consultant to wind farm developers)
•Currently working on one of the FCW
wind farm sites (SSA D) with Airtricity
•Dulas is a Workers’ Co-op with 27 years
experience and 61 staff active in solar,
Wind Farming Essentials
September
2009 RE consultancy
wind, hydro, biomass
and
Turbine
Anatomy
• Blades
• Hub
• Nacelle
• Generator
• Gearbox
• Yaw Drive
• Tower
Wind Farming Essentials
September 2009
Wind Turbine Blades
•
Operate on an aerofoil principle:
•
That is they create a lift force due to the
pressure distribution around the aerofoil
surface
Wind Farming Essentials
September 2009
Wind Turbine Blades
• Blade size is between 20m (600kW
machine) to approximately 50+m (3.6
– 4.5MW prototypes)
• Most commonly made of Glass Fibre
Reinforced Plastic (GRP), but Carbon
Fibre and Wood Laminates are also
used
• Modern turbines are usually 3-bladed.
Wind Farming Essentials
September 2009
Turbine Size –
Rotors and
Blades
• Rated Power
varies with
Rotor Diameter,
but not in a
linear fashion
Wind Farming Essentials
September 2009
The Hub
and Nacelle:
•
•
•
•
Wind Farming Essentials
September 2009
Pitch
bearings
and drives
Gearbox
Generator
Yaw bearing
and drives
Yaw Mechanism
Wind Farming Essentials
September 2009
Turbine Size –
Towers & Hub
Height
• Wind speed
varies with height
above ground due
to WIND SHEAR
• Tower heights
typically between
49m and 100m
Wind Farming Essentials
September 2009
Towers & Hub Height
Reasons to use a taller
towers:
• Greater ENERGY
CAPTURE
• Lower specific
machine loading
due to:
1. Lower shear profile
2. ‘Cleaner’ air flows
i.e. lower turbulence
Annual Energy Output w ith hub height and
m ean w ind speed
7000
Annual Energy Output (MWh/yr)
•
6000
5000
60m
4000
70m
3000
80m
2000
1000
0
6.5
6.75
Mean Wind Speed (m /s)
Wind Farming Essentials
September 2009
7
With the addition of a Control
system these components
enable:
• Optimal capture of the energy in the
wind
• Cost effective generation of energy
• Survivability
Wind Farming Essentials
September 2009
Turbine
Performance
• Power varies
with the cube
of the wind
speed
• Pitch or stall
• Variable or
fixed speed
Wind Farming Essentials
September 2009
Turbine
Performance
• Power curve /
wind speed
• Cut-in (3-4m/s)
• Rated Power
(12-25m/s)
• Cut-out
(25+m/s)
Wind Farming Essentials
September 2009
Wind Farm Design
Other Components of a
Wind Farm include:
• Road access and Grid
Connection
• On-site tracks
• Foundations
• Crane pads
• Sub-station and Control
Room
• Electrical cabling
• Met masts (temporary
and permanent)
Wind Farming Essentials
September 2009
Wind Farm Design
• Access - Good road access is required for
construction and decommissioning
• Modern wind turbines are large, heavy machines
- blades may be up to 44 metres in length and
specialised transport
• Ideally, a site should be adjacent, or very close to
the “A” road network
• Narrow “C” class roads, with tight bends should
be avoided
Wind Farming Essentials
September 2009
Wind Farm Design
• Grid connection – The site should be close to grid
infrastructure at an appropriate voltage (usually 33 132kV)
• Capacity issues – the nearest grid may need
substantial reinforcing for a large development
• Small scale projects particularly need close
proximity to grid connection points
Wind Farming Essentials
September 2009
Wind Farm Design
Layout is dependent on:
• Spacing between turbines
• Distances to properties, roads, footpaths
and bridleways, EMI links
• On-site constraints including
•
•
•
•
Ecology (inc Ornithology)
Hydrology
Archaeology
Topography
Wind Farming Essentials
September 2009
Wind Farm Design
Spacing
between
turbines is
dependant on
rotor
diameter and
wind direction
Wind Farming Essentials
September 2009
Wind Farm Design - EIA
• EMI and Air Safeguarding:
• Extensive list of consultees including MOD,
CAA, NATS, local aerodromes, TV, radio and
microwave operators
• Possible requirement for expert studies in
mitigation of radar, navigational aids, air
safeguarding, radio and TV
• Common mitigation: micro-siting of turbines,
signal boosters, digital receptors,
replace/upgrade equipment
Wind Farming Essentials
September 2009
Wind Farm Design - EIA
• Ecology:
• Baseline studies – habitat survey, bird surveys
and possible invertebrate, mammal and other
protected species surveys
• Detailed appropriate assessments may be
required – bird flight lines, bats, newts etc.
• Mitigation / habitat improvement often important
to compensate for impacts
Wind Farming Essentials
September 2009
Wind Farm Design - EIA
• Archaeology:
• Walkover of the site and desk review of SMR and
aerial photographs
• Assessment of effects and potential mitigation
• Possible requirement for presence during
construction – watching brief
• Usually there is a requirement for Historic
Landscape and Visual Assessment
Wind Farming Essentials
September 2009
Wind Farm Design - EIA
• Noise:
• Operational noise of the turbines is a concern
and often strongly determines wind farm design
and layout
• On-site measurements of background noise
levels and wind speed (correlated)
• Recommended limits
• DTI Noise Working Group guidelines (ETSU ’97)
• Given in relation to existing noise background and
absolute limits
Wind Farming Essentials
September 2009
Wind Farm Design - EIA
• Landscape and Visibility:
• Landscape architects assess effects to
landscape fabric, character and designations,
• Zone of Theoretical Visual Influence (ZTVI) Map
over 30km to illustrate visibility to main view point
receptors
• Photomontages and wireframe representation of
predicted views of wind farm from, on average,
15-20 viewpoints
Wind Farming Essentials
September 2009
Wind Resource
•The UK is the windiest country in Europe with over
40% of the available resource
BUT the wind doesn’t blow all of the time!
•Capacity Factor = Actual Energy Produced /
Rated Power*8760
•Capacity factors range from 28 - 40%
with 30% often used as a general rule.
•Turbines generate 80-85% of the time dependent on
location
Wind Farming Essentials
September 2009
Wind Resource
•The Wind Climate is measured with:
• anemometers (speed)
• wind vanes (direction)
Mounted on temporary or permanent masts
•And characterised in a number of ways:
•Mean wind Speed (at a given height)
•Maximum Gust
•Wind Shear
•Direction
•Turbulence Intensity
Wind Farming Essentials
September 2009
Wind Resource
Wind data processed and presented in various ways
Wind Rose
Histogram
N
W
E
S
Wind Farming Essentials
September 2009
Connection to the Electricity Grid
•
•
•
Wind and other renewable energy generators
are notably different due to:
– Intermittancy
– Size
– Location
Connected to the Distribution system (132kV
and below) rather than the Transmission
system
Hence, known as embedded generation
Wind Farming Essentials
September 2009
Connection to the Electricity Grid
•
•
Constraining issues for wind include:
– Fault levels
– Voltage rise and fall
– Power quality (such as voltage step
changes, voltage flicker and harmonics)
Distribution Network Operator (DNO) will
calculate effect on system using load-flow
analysis and give a connection cost
accordingly
Wind Farming Essentials
September 2009
Connection to the Electricity Grid
•
•
•
•
•
The electricity system is balanced
continuously
Load must be balanced by Generation
Wind is resource dependent in fairly short
time frames
With current and near future penetration
levels (up to the 20% by 2020 figure?)
demand side fluctuation will dominate
Beyond this, storage methods may be
required
Wind Farming Essentials
September 2009
Market Drivers
•
Government policy to increase use of Renewable
Energy
•
Recent DTI/Carbon Trust Report concluded that wind
is “the only scaleable technology and will deliver the
majority of the 2010 Target”
•
Similar conclusions in TAN 8 2005
•
Target of 15.4% of electricity from RE by 2015 and
new EU target of 20% by 2020
•
Renewables Obligation is the financial driver in the
UK
Wind Farming Essentials
September 2009
Market Drivers
Renewables Obligation
 All electricity suppliers to acquire 10% of their
electricity from RE by 2010
 The costs may be passed to customers
 Regulator responsible for supplier compliance
Contract terms determined between
suppliers/generators themselves
 Suppliers that do not meet their obligations are
effectively fined through a “buyout” levy for the
proportion of MWh of RE they fail to secure
Wind Farming Essentials
September 2009
Turbines and Trees
Wind Farming Essentials
September 2009
Turbines and Trees
• Manufacturer’s perspective =
DO NOT SITE TURBINES NEAR TREES
• Developer’s perspective =
TAKE OPPORTUNITIES WHERE AND
WHEN THEY ARISE
• Both will face the same problems….
Wind Farming Essentials
September 2009
Turbines and Trees
•
•
•
•
Reduced Wind Speed
Increased Turbulence Intensity
Increased Wind Shear
Increased Uncertainty in Resource
Assessment
• Increased Uncertainty in Turbine Power
Curve
• Increased Turbine Loading
• Reduced Turbine Availability
Wind Farming Essentials
September 2009
Wind Farm Design Tools
•
•
•
•
•
WindFarmer, Wind Farm, Wind Pro
WAsP (potential flow, rules of thumb)
CFD and Hybrid codes
Measure Correlate Predict (MCP)
Geographical Information Systems
(GIS)
Wind Farming Essentials
September 2009
Wind Farming Essentials
September 2009
Wind Farming Essentials
September 2009
Wind Farming Essentials
September 2009
THANK YOU
Wind Farming Essentials
September 2009