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The Turby concept
The necessity for renewable energy– Large wind turbines - public issues– Photo- Voltaïcs - not economical– Small wind turbines - attractive, but need height– Height essential - but expensive
Use available height BUILDINGS
Urban Turbines
Design criteria
Safety
Good price / performance ratio• Good efficiency• Low cost of manufacturing• Low additional costs for transport and erection• Maintenance free
No impacts• vibrations • noise • flickering / shade
Fundamental choicesAXIS: Horizontal (HAWT) or Vertical (VAWT) ?• VAWT mechanically simpler• aerodynamically more complex
ROTOR: Impulse type or aerodynamic ?Impulse type (Savonius)- extracts energy in the direction of the flow- ɖ theoretical < 19 %
Aerodynamic (lift) type rotor- extracts energy perpendicular to the flow- ɖ theoretical < 59 %
Turby is an aerodynamic VAWT
VAWT: Basic principle
• Angle of attack [Ŭ] :– Blade speed (rotational speed x radius) & Wind speed– Ŭ < 150 : ENERGY; Ŭ > 150 STALL
• To prevent stall: Blade speed > 3-4 x wind speed
Blade speed
Wind
Angle of attackApparent wind
Rotating rotor "sees" a rotating wind
The best known VAWT: Darrieus
• Rotational speed same over length of axis
• Radius varies• Blade speeds varies
• Near shaft: STALL vibrations• In middle Ŭ å 00 noise• In between: lift energy
• Little effective use of rotor surface
Turby’s solution
• Constant radius
• Uneven number of blades
• Blades twisted to smoothen the effects change of wind direction
Turby meets design goalsSafety
Survival wind speed > 55 m/sKevlar inlay - blades may crack but will not shatter2 independent brake systems / vibration control
Price / performanceGood efficiency Few systemsEasy transportation and installationMaintenance free
ImpactsNearly vibration freeNoise level 70 dB(A) at 5 m distanceSmall blades matte finish
Yield
Available wind energy• Macro average wind speed in the area• Micro roughness of the terrain
• height• increase in wind speed over obstacles• undisturbed wind flow from all directions
Properties of the windturbine• Efficiency• Suitability for local conditions
• turbulence• temperatures• snow and icing
Yield II• Effect of
averagewindspeed
• Effect of height
Annual yield - average windspeed
0
12
3
4
5
6
7
8
4 4,5 5 5,5 6 6,5 7
v wind average [m/s]
MW
h
Annual yield - height
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0 10 20 30 40 50 60 70 80
height of tower
kWh
Yield varies with area and heightAnnual yield - height and roughness length for the Netherlands
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0 10 20 30 40 50 60 70 80
height of tower [m]
yiel
d [k
Wh]
Each of these 100 linesrepresents a 1% area of the Netherlands
Wind speed range
0
500
1000
1500
2000
2500
3000
0 5 10 15 20
wind speed
h / W
0
50
100
150
200
250
300
350
400
450
500
kWh
wind speed distributionpower curveenergy production [kWh]
Effect of direction
0%
2%
4%
6%
8%
10%
12%
14%
0 t/m 4 m/s5 t/m 12 m/s> 12 m/stotaal
A free flow from all sides is important
Wind over buildings
• above the roof.• near centre of roof• undisturbed flow from all sides
• Wind speeds 1,2 – 1,4 x higher! > 2 x more energy
Local conditions
0
4
8
12
16
20
24
28
-15 -10 -5 0 5 10 15 20 25 30 35
Temperature [C]
Win
d sp
eed
[m/s
]
De BiltEeldeVlissingen
Status• Turby concept August 2000• Windtunnel tests 2001• Full scale prototype March 2002• Testing – engineering 2002 / 2003• Final prototype January2004• Prototype series 24 units 7 installed 2004
Experience:• No breakdowns, no safety issues• No adverse impacts
Preparing for commercialization:• Fine tuning the software• System dynamics roof – pole - turbine
A very early adapter
Number ONE
Ÿ Ŷ
On the roof
Other installations
A computer representation
