The Turby concept
The necessity for renewable energy
– Large wind turbines
-
public issues
– Photo
-
V
oltaïcs
-
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 choices
AXIS:
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
-
Ș
theoretical
< 19 %
Aerodynamic (lift) type rotor
-
extracts energy perpendicular to the flow
-
Ș
theoretical
< 59 %
Turby is an aerodynamic VAWT
VAWT: Basic principle
• Angle of attack [
Į] :
– Blade speed (rotational speed x radius) & Wind speed
–
Į < 15
0
: ENERGY;
Į > 15
0
STALL
• To prevent stall:
Blade speed > 3-4 x wind speed
Blade speed
Wind
Angle of attack
App
are
nt w
ind
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
Į § 0
0
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 goals
Safety
Survival wind speed > 55 m/s
Kevlar inlay - blades may crack but will not shatter
2 independent brake systems / vibration control
Price / performance
Good efficiency
Few systems
Easy transportation and installation
Maintenance free
Impacts
Nearly vibration free
Noise level 70 dB(A) at 5 m distance
Small 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
average
wind
speed
• Effect of
height
Annual yield - average w indspeed
0
1
2
3
4
5
6
7
8
4
4,5
5
5,5
6
6,5
7
v wind average [m/s]
MWh
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
kW
h
Yield varies with area and height
Annual 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]
yi
e
ld
[
k
W
h
]
Each of these 100 lines
represents 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
kW
h
wind speed distribution
power curve
energy production [kWh]
Effect of direction
0%
2%
4%
6%
8%
10%
12%
14%
0 t/m 4 m/s
5 t/m 12 m/s
> 12 m/s
totaal
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]
W
in
d
sp
eed
[
m
/s]
De Bilt
Eelde
Vlissingen
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
ĺ
ĸ
On the roof
Other installations
A computer representation
