Energy Blowing in the Wind N. Keith Tovey, M.A., Phd. CEng, MICE Acknowledgement: Dr Jean Palutikof for use of some of her slides.

Energy Blowing in the Wind

N. Keith Tovey, M.A., Phd. CEng, MICE

Acknowledgement: Dr Jean Palutikof for use of some of her slides

Renewables Target

•10% by 2010 for Electricity Generation

•20% by 2020

The European Commission directive 2001:

Member States are required to adopt national targets for renewables that are consistent with reaching the Commission’s overall target of 12.1 per cent electricity from renewables by 2010. UK’s indicative target is 10 per cent electricity.

The Energy Review 2002

Early Wind Power Devices

C 700 AD in Persia

•used for grinding corn

•pumping water

•evidence suggests that dry valleys were “Dammed” to harvest wind

Traditional Windmills

American Homestead

Windmill for pumping water

Traditional English Windmill

Spanish Windmills

Note 7 in a cluster of 11

Development of Modern Turbines

1.25 MW Turbine in Vermont (1941) Gedser Wind Turbine, Denmark (1957)

Vertical Axis Machines

Musgrove Rotor

Carmarthen Bay 1985 - 1994

Darrieus Rotor - machines up to 4 MW have been built.

Other Wind Machines

Savonius Rotors - good for pumping water - 3rd World applicationsModern Multi-bladed water pumping HAWT.

What’s a modern wind turbine look like?

Based on slide by Dr J. Palutikof

The Ecotech Turbine avoids having a high speed gear box in the nacelle

Ecotech wind turbine

• Electricity per annum 3.9 GWh

• Annual homes equivalent 938

Displacement pa:

• CO2 3000 tonnes

• SO2 39 tonnes

• NOx 3 tonnes

67m

66m

Dr J. Palutikof

We could make CO2 targets with all new electricity generation from gas, but then 75% of our electricity will depend on supplies of gas from Russia, Middle East, or North Africa

These figures assume we achieve 20% renewable generation by 2022

Energy Scenarios for UK and implications on CO2 emissions.

Options for Electricity Generation in 2020

- Non-Renewable Methods

potential contribution to

Electricity Supply costs in 2020

Gas CCGT0 - 80% (currently 40% and rising)

available now, but UK gas will run out within current decade

~ 2p +

nuclear fission (long term)

0 - 60% (France 80%) - (currently 20 - 25% and falling)

new inherently safe designs - some practical development needed

2.5 - 3.5p

nuclear fusion

unavailablenot available until 2040 at earliest

"Clean Coal"

Traditional Coal falling rapidly -

coal could supply 40 - 50% by 2020

Basic components available - not viable without Carbon Sequestration

2.5 - 3.5p

Options for Electricity Generation in 2020 - Renewable

Ultimate potential contribution to

Electricity Supplycosts in 2020

On Shore Wind ~25%available now for commercial exploitation

~ 2p

Off shore wind 25 - 50%some technical development needed - research to reduce costs.

~2.5 - 3p

Hydro 5%technically mature, but limited potential

2.5 - 3p

Photovoltaic 50%available, but much research needed to bring down costs significantly

10+ p

Energy Crops 100% +available, but research needed in some areas

2.5 - 4

Wave/Tidal Stream 100% +techology limited - extensive development unlikely before 2020

4 - 8p

Tidal Barrages 10 - 20%technology available but unlikely without Government intervention

not costed

Geothermalunlikely for electricity generation before 2050 if then

Renewable Energy comparisons

In the home - on average 25 - 40 sq m of PhotoVoltaic Cells would provide the equivalent of the electricity requirements of the house

Approximate Annual ProductionArea to produce same

output at Sizewell

UK Electricity Demand 2001 345 billion units

Sizewell Nuclear Power Station 7.2 billion units

Wind (Ecotech) 3.9 million units per turbine 800 + sq km

Biomass 1.5 million units per square km 4000 sq km

Solar PV 70 - 150 units pers sq m 100+ sq km

Tidal (Severn Barrage)

17 - 25 billion units

Distribution of Renewable Projects

The UK target for New Renewables set in 1993, was the building of 1500MW of new renewable capacity by 2000.

How did we do?Position at 30th June 2000

Technology Projects Capacity MW

Biomass 6 64.284Hydro 56 38.798Landfill Gas (LFG) 154 322.378Municipal and Industrial Waste (MIW) 15 190.349Sewage Gas 24 25.039Wave - -Wind 69 161.2

Total 324 802.048

compared to planned 1500

As of 30th September 2001 377 954.6

Projects Turbines Installed Capacity Avergae Turbine Size(MW) (kW)

70 948 482.6 509

Emission Savings

Mtonnes Mtonnes Mtonnes

from Wind Turbines 1.24 0.013 0.0039

UK Emissions

552.9 1.21 1.61

Wind Energy in UK (end of 2001)

Million TonnesCarbon Dioxide Sulphur Dioxide Oxides of Nitrogen

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Increase in Renewable Component for Electricity Generation to meet Government Target of 10% by 2010

Note: If we meet this target, it will hardly change the non-renewable component - i.e. the renewable deployment will just keep pace with increase in demand.

Even if we do meet target (which is far from certain), our CO2 emissions will rise following from closure of nuclear plant.

National Demand for Electricity also changes rapidly

Prices paid by Suppliers vary dramatically over the day

The introduction of NETA on 27th March 2001 had an adverse effect on economics of Renewable Energy and CHP

UK Electricity Demand

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14-15th May 2002

How are we going to meet these demands for electricity in the future? The Energy Review indicates 10% by renewables by 2010 and 20% by 2020.

“In order to get more than 10% of electricity from renewables by 2010 and 20% by 2020, build rates for the leading options would need to be at levels never before seen in the UK. Onshore and offshore wind would need to be installed at a rate of between 1-2 GW per year “(i.e. 1000 - 1500 turbines the size of Swaffham every year).

“However, 1.5 GW and 1.6 GW of onshore wind was built in Germany in 1999 and 2000 respectively, and a further 1.2 GW was installed in the first eight months of this year (2001). Build rates of 1 GW per year were also seen Spain in 2000, and 600MW in Denmark in the same year.”

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Wind Energy in Europe

Currently 13,000 MW from wind energy

Overall EU target of 12% of energy (22% electricity) from renewables by 2010 - UK 10%

Onshore Offshore

(MW) (MW)

2010 60000 5000

2020 150000 50000

Onshore Wind Turbines in Denmark

Wind Map of Western Europe: wind resource at 50m above surface

Sheltered Open Coast Open sea Hills

Dr J. Palutikof

Wind map of UK

• The detailed picture is much more complex:

– Topography

– Distance from sea

– Roughness

– Obstacles

Dr J. Palutikof

Power in the wind

Kinetic Energy in Wind

=

where = air density

R = blade radius

V = Wind Velocity.

Because wind cannot come to standstill, only 59.26% is actually available - The Betz Efficiency0

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Kinetic Energy In Wind

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Rated Output

Power Curve for Vestas V63 - 1500 kW Wind Turbine

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Annual output depends of wind speed distribution

Using a typical Wind Speed distribution gives a load factor of around 30%

~ 70 - 80% for fossil fuel stations and nuclear.

Actual load factor does depend on

•Wind Speed Distribution Curve

•Turbine Rating Curve

Prevailing Wind direction can vary significantly as shown by the two rosette plots from stations 150 km apart.

Effect of a forest of trees 20 m tall on output from turbine.

At a hub height of 2.5 times trees and 15 tree heights downwind, 16% of energy is lost.

Obstructions can affect output for significant distances downwind.

Image obtained from www.windpower.org

Wind Speed variation with elevation above ground

Swaffham

Proposed Shipdam

Depends on roughness of terrain

Increasing hub height increases power by 10%.

The wind speed increases logarithmically with elevation.

Spacing of Wind Turbines

•Interference between adjacent turbines occurs if spacing is less than 7 - 10 blade diameters - “The Park Effect”.

•With large arrays, 10 - 20% reduction in output will occur with a spacings of ~ 5 blade diameters.

•Because of square law of swept area, and larger turbines requiring greater spacing, the effective harvest of the wind is approximately the same irrespective of turbine size.

•However, costs will come down with fewer larger machines.

Proposed Offshore Wind Turbine locations

Current Onshore Wind Turbine locations

Wind Turbine Locations

•Distraction to drivers•Danger to birds•Radio/Television/Radar Interference•Noise - mechanical, aerodynamic, …..infra-sound?•Flickering

- only relevant within buildings and then only in a precise orientation at selected times of the year.

•Danger of ice throw

- not really a problem as other constraints will mean that a sufficient exclusion zone is present anyway

•Blade failure

•Aesthetics -

one blade, two blades, three blades, Darrieus, Musgrove?

Key Environmental Issues - some of main issues against

Ice can form

but if this occurs when stationary, the machine will not start

if it forms in operation, then the out of balance on blades is detected and the machine will stop in a few revolutions.

Worse case scenario would cause ice to be thrown distances much less than the exclusion zone for noise.

In Denmark, a noise limit of 45 dB is set for isolated houses or 40 dB where several houses are affected.

Two turbines close together would increase noise by about 3dB, while increase for 10 would be 10 dB

Noise issues

Rule of thumb for noise

• EuropeDistance to houses should be > 7 rotor diameters or ~300 m = 1000 ft.

• USA

Dr J. Palutikof

Noise issues:

Mechanical

Aerodynamic

Infra-sound

Problem with high-speed gearboxes in fixed velocity machines.

Not an issue with Swaffham/ proposed turbines at Shipdham.

Maximum rotation speeds of gearboxless turbines are at a maximum 70% of normal wind turbines, and often much less - hence much less “swish” noise.

This is a subject which is not fully understood - it is at a frequency which would NOT be detected by normal ground vibration.

Noise Contours for a cluster of three turbines at Shipdham

> 30 dB

> 40 dB

> 50 dB

One Blade, or Two, or Three?

Visual intrusionSome designs look better than others

.. and some arrays look better than others

Dr J. Palutikof

Managing Environmental Issues

•Safety Issues

•Visual Issues

•Noise Issues

•Bird Strikes

•TV/Radio Interference

First three can be managed using GIS procedures.

Exclusion zones can be drawn for each feature type.

Digital Map of part of Norfolk

Norwich is in bottom left hand corner

Area: 105 sq kms

A Strategic assessment of Wind Energy / Biomass Potential

Number of Turbines

65

Mean output

24.4 MW

Area for Turbines

20.7 sq km

Minimum exclusion zone (400m) around houses/towns.

We could add other Planning exclusions etc - areas of particular landscape value etc.

Number of Turbines

33

Mean output

12.4 MW

Area for Turbines

10.2 sq km

Large exclusion zone (800m) around houses/towns.

Offsets the use of fossil fuels and consequential gaseous emissions of CO2, SO2, NOx, CO, NMHC etc.

Arguements that fossil fuel power stations have to be kept ready in case wind drops are completely INVALID. Power stations running under lower load use less fuel and it is this which causes the emissions.

Improves diversity of supply of electricity

will become of increasing importance in future

Is becoming technically mature

unlike most other renewable technologies (other than energy from waste incineration and hydro)

Is the most cost effective Renewable Option currently available, and will remain so for next decade +

As electricity will used locally, reduces transmission losses.

Key Environmental Issues of Wind Energy - positive aspects

Offshore wind energy - A solution?

BUT

• Wind speeds are high

• Resource is enormous

• Visual intrusion is less than for onshore

•It’s expensive•Maintenance is problematic

Test location for offshore Wind Turbines in Denmark

Existing European offshore wind farms

Location Country Online MW No RatingVindeby Denmark 1991 4.95 11 Bonus 450kW

Lely (Ijsselmeer) Holland 1994 2 4NedWind 500kW

Tunø Knob Denmark 1995 5 10 Vestas 500kWDronten (Ijsselmeer) Holland 1996 11.4 19 Nordtank 600kWGotland (Bockstigen) Sweden 1997 2.75 5

Wind World 550kW

Blyth Offshore UK 2000 3.8 2 Vestas 2MWMiddelgrunden, Copenhagen Denmark 2001 40 20 Bonus 2MWUttgrunden, Kalmar Sound Sweden 2001 10.5 7 Enron 1.5MW

Yttre Stengrund Sweden 2001 10 5NEG Micon NM72

90.4 83Totals

Dr J. Palutikof

How much energy?

Size of the resource

• This is based on 1999 consumption figures and is a little optimistic with regard to spacing of turbines - a more realistic figure is given by 40km x 40km

From BWEA Web Site

Examples of Offshore Wind

•Wind Energy has matured in the last decade.

•Significant developments are Wind Energy are likely in next decade both onshore and offshore if UK is to meet its targets.

•However, planning issues may continue to hinder development. In decade to 2000, 1100 MW were proposed, but less than 200 MW were built.

•We need to manage it to our benefit.

Conclusions

When questioned, typically 70 - 80+% of the public are in favour of Wind Energy, but the opponents are very vociferous.