harvesting wind energy in a city

harvesting wind energy in a city

MSc Christina Beller

Wind Energy Division, AED Risø DTU National Laboratory for Sustainable EnergyWind Energy Division, P.O. Box 49, 4000 Roskilde, DenmarkTel: +45 4677 5434, e-mail: [email protected]

Risø DTU, Technical University of DenmarkRisø DTU, Technical University of Denmark Grøn BIM

Content

•Introduction

•Urban Wind Turbines

•Wind Conditions

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Risø DTU, Technical University of DenmarkRisø DTU, Technical University of Denmark

INTRODUCTION

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Wind Energy History

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Key Figures within Wind Energy Production-rotor design-The idea with a wind turbine is to transform some of the energy in the wind in useable energytheory

power production: maximum power coefficient:P = ½ v3 A CP CP=16/27=0.593

in practicemaximum power coefficient small WT in the kW range have a CP=0.5 for MW turbines maximum CP between 0.3 and 0.4.

http://www.flatrock.org.nz/topics/environment/energy_options.htm http://logik.dk/site/referencer/referencer-byvindmoller

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http://www.flatrock.org.nz/topics/environment/energy_options.htm

http://logik.dk/site/referencer/referencer-byvindmoller


Key Figures within Wind Energy Production-siting-

Load factor: actual power output at specific site/ maximum rated output

Load factor ~30%-40% Load factor ~10% for small-scalefor off-shore MW turbines [1] building mounted WT and ~17% for free standing turbines [1]

A wind field trial in UK showed, that the 57 domestic installed wind turbinesreached up to a load factor of only ~3%.

Among the monitored wind turbines, a 1.5kW building mounted windturbine had the maximum load factor yield with 7.4%.

[1] http://www.energysavingtrust.org.uk/Global-Data/Publications/Location-location-location-The-Energy-Saving-Trust-s-field-trial-report-on-domestic-wind-turbines

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http://www.energysavingtrust.org.uk/Global-Data/Publications/Location-location-location-The-Energy-Saving-Trust-s-field-trial-report-on-domestic-wind-turbines

http://www.energysavingtrust.org.uk/Global-Data/Publications/Location-location-location-The-Energy-Saving-Trust-s-field-trial-report-on-domestic-wind-turbines


Calculation Exampleannual energy consumptionsingle house hold: 1800 kWh/year2 persons: 2500 kWh/year4 persons: 4000 kWh/year

annual energy productiona 1kW WT produces according to wind climate, positioning and design:24h * 365days * rated power * load factor = 700kWh/yearthat corresponds to ca. 200kWh/year per m2 (3.61m2 in total)and to about 28% of the energy needs of a 2 persons house hold

a 2MW WT positioned off-shore (e.g.Middelgrund) produces approximarely: 24h * 365days *rated power * load factor = 5256000kWh/yearthat corresponds to ca. 1168kWh/year per m2 (4500m2 in total)and to about 100% of 2100 house holds with two persons

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public - street lamps- city bikes- fountaines- …

private - low voltage grid (12V/24V)- private power plant

generel, energy should not vanish in the grid,no new needs shall be invented anddirect connection between generation and usage shall be maintained

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bruger230V

bruger 230V 12V

bruger12V

230V

…

12Vbruger 230V

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How should the Energy be used


URBAN WIND TURBINES

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• Integrated in buildings structure

• Mounted on already existing buildings

• Free standing turbines

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concept study

two Proven6 horizontal wind turbines, Blackpool, UK vertical wind turbine on a flat roof, UK

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Wind Energy in the Urban Environment


Example for integrated Designs

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www.bahrainwtc.com

Bahrain World Trade Center in Bahrain, designed by The Atkins

Note:Three 29m diameter wind turbines are supposed to deliver 11-15% of the energy needs of the building.

http://www.bahrainwtc.com/


More Examples for integrated Designs

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STRATA (formerly known as Castle House) in London, designed by BFLS (formerly Hamilton Architects)

Note:The three 9m diameter wind turbines are estimated to deliver 8% of the energy needs of the building.

http://www.stratalondon.com/home

http://www.stratalondon.com/home



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Pearl River Tower in Guangzhou, China, designed by: SOM

Note: Besides wind turbines in the slots, photovoltaics are integrated (BIPVs) in the facade. They provide about 10% of the energy consumption.

http://www.bryanchristiedesign.com/portfolio.php?illustration=576&category=37&open=

http://www.som.com



http://www.som.com/



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COR in MIAMI, designed by: Oppenheim Architecture + Design


most projects were feasibility studies and were not continued

Some manufacturers made promises to customer, which they could not fulfill bad reputation for the branch of small wind turbines

In the end UK got pretty active in the area of small or so-called micro wind turbines

sizes range from 1 to 20m diameter and the rated power from 100W to 100kW

to get the peoples acceptance, the design has to be aesthetic and reliable

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QuietRevolution, UK

vertikale møller, UK

Proven, UK

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Turbines mounted on existing Buildings


Use the energy for public needs Not necessarily connected to a building

Prevent that neighbors get irritated, while they do not gain anything from it Usage should serve everybody

example Blackpool:

Spectacular lightning in the city – supported by decentralized wind energy of two “Proven 6” turbinespositioned at coastal site, like Copenhagen

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Lakes in Copenhagen

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Free standing Wind Turbines

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Vertical axis H-rotor typeQuiet Revolution (6kW)Manufacturer: QuietRevolutionConcept: 3 bladed lift-drivenAxis: Vertical axisRated Power (at 12.5m/s): 6.0kWDiameter: 3.1mHeight: 5.0mSwept area: 15.5m2

http://www.quietrevolution.co.uk/qr5.htm

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http://www.quietrevolution.co.uk/qr5.htm

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Vertical axis H-rotor typeVenco Twister 1000T/1000TL(1kW)Manufacturer: VencoConcept: 3 bladed lift-drivenAxis: Vertical axisRated Power (at 12m/s): 1.0kWDiameter: 1.9mHeight: 1.9mSwept area: 3.6m2


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GODKENDT

i DK


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Vertical axis H-rotor typeMariah Power (1.2kW)Manufacturer: Mariah PowerConcept: 3 bladed lift-drivenAxis: Vertical axisRated Power (at 11.2m/s): 1.2kWDiameter: 1.2mHeight: 6.1mSwept area: 7.3m2

http://www.mariahpower.com/windspire-overview.aspx

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http://www.mariahpower.com/windspire-overview.aspx

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”Vertical axis” Savonius/H-rotor typeAerotecture (1kW)Manufacturer: AerotectureConcept: 2 bladed drag-lift hybrid Axis: Tilted Vertical axisRated Power (at 14m/s): 1.0kWDiameter: 1.5mHeight: 2.8mSwept area: 4.2m2

http://www.aerotecture.com/products_520H.html

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http://www.aerotecture.com/products_520H.html

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Horizontal axis up-wind and passive yawing proCure (600W)Manufacturer: proCure A/SConcept: 3 bladed up-wind lift-drivenYaw Control: PassiveAxis: HorizontalRated Power (at 12.5m/s): 0.6kWDiameter: 1.8mSwept Area: 2.5m2

http://www.procure.dk/moeller.htm

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GODKENDT

i DK

http://www.procure.dk/moeller.htm

http://www.procure.dk/billeder/produkter/moellebilleder/moelle8.htm

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Horizontal axis up-wind and active yawing Wind Energy Solutions (2.5kW)Manufacturer: Wind Energy SolutionsConcept: 3 bladed up-wind lift-driven Yaw Control: ActiveAxis: HorizontalRated Power (at 9m/s): 2.5kWDiameter: 5.0mSwept Area: 19.6m2

http://www.windenergysolutions.nl/files/foto/big/tu1.jpg

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http://www.windenergysolutions.nl/files/foto/big/tu1.jpg

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Horizontal axis up-wind BellAIR (3W)Concept: 2 bladed up-wind lift-drivenAxis: horizontalRated Power (at 7m/s): 3WDiameter: 0.27mSwept Area: 0.06m2

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Horizontal axis up-wind BellAIR (3W)

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Mounted on, e.g. a bike, the citizen is cycling and generating most of the wind. While the bike is parked and wind is blowing, energy is produced, meant to charge small electrical items.


WIND CONDITIONS

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Wind Climate On-Shore

Risø DTU, Technical University of DenmarkRisø DTU, Technical University of Denmark27

wind profiles

Wind inbetween and around buildings

H.C. Ørsteds institute roof top, windrose

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Wind Climate in Cities


Parametric City


[2] Badde O, Plate EJ (1994) Einfluss verschiedener Bebauungsmuster auf die windinduzierte Gebäudebelastung. In: Abschlusskolloquium Strömungsmechanische Bemessungsgrundlagen für Bauwerke. University of Karlsruhe

Parametric City-quarter classification-


Parametric City-configuration seven-

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Parametric City-pressure distribution-

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Flow direction: α = 90⁰

Pressure distribution on the surface.

Red:Areas of high pressure indicating low velocities.

Blue: Areas of low pressure indicating high velocities.


Parametric City-streamlines 1-

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Streamlines surrounding the obstacle.

Accelerated flow in the entrance urban canyon, not maintained, but lifted up over the rear building.



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Streamlines sharply decelerated at the facade (high pressure).

Main parts surround the building, loosing velocity in the wake areas of the array.

A small fraction flows over the buildings roof top and gets accelerated at the edge (low pressure).



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Streamlines hitting the outstanding tower are deflected.

Anyway, a reasonable speed is maintained.



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Parts of the streamlines are deflected downwards at the tower’s façade

and get decelerated remarkable.



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Flow over in-line obstacles of a constant high remains undisturbed, but slightly lifted in height gradually.


Parametric City-stamps 1-

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First row:High speeds due to undisturbed inflow.



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First row:The undisturbed flow is deflected strongly at the first row’s façade, forming a speed profile on the roof top’s front edge.

Second/third row:Buildings inside the array and of the same height as their up-steam buildings experience homogeneous speed distributions along the roof top



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Speed distributions above roof level are maintained in areas with buildings of the same height, although distances may vary to a certain extend.



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Outstanding buildings: The part of a building higher than the up-stream building experiences the ‘first-row’ effect.

Buildings behind them:In wake areas the flow is more turbulent and the speed is very low.

The wake recovers depending on the down-stream situation.


Parametric City-overview-

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Risø DTU, Technical University of DenmarkRisø DTU, Technical University of Denmark SEB'10 Christina Beller

Parametric City-meterological masts-

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090

000

180

270

pole1

pole2pole3

Risø DTU, Technical University of DenmarkRisø DTU, Technical University of Denmark SEB'10 Christina Beller

Parametric City-meterological masts-

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Wind Turbines in Urban Environment• Christina Beller, Urban Wind Energy – State of the Art 2009, Risø-R-

1668(EN), October 2009

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harvesting wind energy in a city

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