Witam Ten plik z filmikiem z Discowery, do którego linka wkleił kilka postów wcześniej kol. greenpeace dotyczy turbiny o wdzięcznej nazwie TURBY. Na stronie producenta ( www.turby.nl ) jest troche info o turbinie, ale z wiadomych przyczyn nie wszystko i w dodatku w języku Szekspira. Cena turbinki z generatorem to ok 12k ojro . Nawet myślałem żeby coś takiego zrobić w znacznie mniejszej skali, ale pewnie do wykonania płatów trzeba użyć kosmicznych technologi.:cry: Tak więc powstanie najprawqdopodobniej klasyczny h-rotor. Plik który załączam można pobrać ze stronki producenta
The wind turbine for the built-up environment
Wind energy and power
Wind turbines use the kinetic energy of
the wind. The kinetic energy of a
moving body is known through the
formula: Ekin= 1/2 .m.v?, in which m is
the mass of the moving body and v is
This formula is applicable for wind if
one calculates for the mass the amount
of air flowing per second through an
area of 1 m2. The result is energy per
second, power [W] instead of energy.
For a wind turbine with a swept area of
A m? the total mass passing per second
through the rotor is equal to the swept
area A times the speed of the air v
times the density of air ?, in formula:
m = ?.v.A.
Substitution of the latter formula in the
former one leads to the formula for the
power offered by the wind to the
turbine: Pwind = 1/2 . ?.v?.A
Since the density of air is 1.2 kg/m? the
available power per m? rotor area is
equal to 0.6 x v? Watt.
At a wind speed of 4 m/s, v? = 64 and
the power per m2 swept area: 0.6 x 64
= 38 W. At 5 m/s wind speed, the
power is 75 W and at 6 m/s wind speed
130 W! See the graph below.
Note: The swept area of Turby is 5,3 m2.
Power in wind versus windspeed
Power [ W/m2]
Turby is a revolutionary vertical axis
wind turbine especially designed for
use in an urban or built-up
This document is
written as a guide for anyone
interested in its development and
The characteristics of different types of
wind turbines in general and the
physical principles of Turby in
particular are explained. Attention is
given to the behaviour of wind,
especially in an urban or built-up area.
The behaviour of Turby is analyzed and
conclusions are drawn regarding the
optimum position for a vertical axis
wind turbine on the roof of a building.
Finally potentially adverse effects on
the building are discussed.
It is hoped that after reading this
guide, you will be able to determine
whether the application of Turby in
your specific situation is practical and
wind speed [m/s]
It is important to understand this
phenomenon well since it explains why
a relatively small difference in average
wind speed results in a big difference
in the energy output of a wind turbine!
Wind turbine types and efficiency
There are two essentially different
types of wind turbines:
Impulse type wind turbines
(Savonius rotors) are vertical axis wind
turbines with blades covering the
whole swept area and shaped to offer a
high resistance to the wind coming in,
in the direction of the rotation and as
little as possible resistance to wind
blowing to the other side of the blade.
Aerodynamic wind turbines have
wingshaped blades covering a small
percentage of the swept area; the wind
flow along these blades generate a lift
force - as with airplanes -
perpendicular to the flow.
Not all the energy in the wind can be
converted by a wind turbine because
the wind speed directly behind the
rotor would become zero, thus clogging
a further flow through the rotor. Newly
arriving wind would be forced to
choose its way around the rotor and
the energy in that wind is not
converted. In reality part of the air will
flow through the rotor and part around
it; the ratio of these parts determines
the efficiency of the turbine. The
physicist Betz has theoretically proven
(1919) that this efficiency depends on
the type of rotor. A modern
aerodynamic turbine has a maximum
theoretical efficiency of 59% and
impulse type turbines 19%. It may be
counter-intuitive that devices covering
the whole swept area have such a low
efficiency, but sailors will recognize
this: "Sailing before the wind" is far
less energetic than " close hauled" or
" half wind " .
It can also be understood from the
formula derived above. The blades of
impulse type turbines are dragged by
the wind in the direction of the wind;
the faster the rotor turns the lower the
difference in speed between blades and
wind and consequently the lower the
transfer of power.
Aerodynamic turbines derive their
power by moving perpendicular to the
wind; an increase in blade speed will in
first instance effect in an increase of
the power transfer instead of a
reduction! Due to their low blade speed
impulse type turbines are assumed to
produce little noise. This is only
marginally true. The "air speed" of the
returning blade is equal to the wind
speed plus the speed of the dragged
blade, near twice the wind speed; the
rotor of an impulse type turbine has to
be at least three times larger than an
aerodynamic rotor to generate the
same energy. Since the noise level of
an object moving through the air is
determined by its speed and its size,
the noise level of both types of turbines
generating similar amounts of energy
is practically the same.
A typical Savonius type turbine
Aerodynamic wind turbines.
Aerodynamic wind turbines can be
divided into two main types, horizontal
axis wind turbines [HAWT] and
vertical axis types [VAWT].
All big wind turbines are horizontal
axis engines, just like the traditional
familiarity has given the development
of horizontal turbines a higher priority
than that of vertical turbines. Modern
HAWTs have usually a rather high
efficiency but their construction is
expensive. They have to be directed in
the direction of the wind, either
manually or by the use of a sensorbased control mechanism- adding
again to its costs! Vertical-axis turbines
do not need such a control system; it is
completely irrelevant from which side
the wind blows; the position of the
rotor is always right.
wind throughout the whole revolution
coming in as a headwind with only a
limited variation in angle. Cyclist will
recognize that effect, if one goes fast
enough there is always headwind.
Seen from the blade the rotational
movement of the blade generates a
headwind that combines with the
actual wind to the so called "apparent
wind". If the angle of attack of this
apparent wind on the blade is greater
than zero the lift force has a forward
component that propels the turbine.
The angle should not exceed 20° since
at higher angles the flow along the
blade is no longer laminar - which is
required for a lift force - but becomes
turbulent. This phenomenon is known
as "stall"; it was the cause why mid 20th
century small airplanes literally fell
from the air when they climbed to
An angle of attack between zero and
200 requires a sufficiently high blade
speed. Therefore a Darrieus turbine
cannot be self starting; it needs to be
brought to a sufficiently high blade
speed by external means. But the lack
of a control system to pint the turbine
into the wind amply compensates for
the disadvantage of not being selfstarting.
The original Darrieus turbine suffered
from negative features such as violent
vibrations, a high noise level and a
relatively low efficiency, thereby
severely limiting its success.
The first aerodynamic vertical axis
wind turbine was developed by the
Frenchman Georges Darrieus and first
patented in 1927. Its principle is a
blade speed being a multiple of the
wind speed resulting in an apparent
Turby's developers have analysed why
these less favourable characteristics
occur, and based upon their analysis
developed a significantly improved
concept for a vertical axis wind turbine
- the Turby! Turby's design eliminates
all of the less desirable characteristics
Note: Obviously the angle of attack
during a revolution varies between
- 200 and + 200.
The Turby concept
The strong vibrations, high noise levels
and the low efficiency characterising
the Darrieus turbine are caused by the
flow of air around the blade.
As explained the angle of attack of the
apparent wind should not exceed 200.
The rotational speed of the turbine is
for all parts of the blades the same, but
since on a Darrieus turbine the
distance between blade and shaft
varies, the blade speed varies also.
On the blade parts near the shaft the
self-generated headwind is low; at the
curve of the blade, at the greatest
distance from the shaft, its reaches a
The low blade speed close to the shaft
results in an angle of attack of the
apparent wind that over large parts of a
revolution exceeds the allowable value
with stall as a consequence.
There are moments of laminar flow
and moments of turbulence resulting
in intermittent lift power and drag on
the blades and this causes vibrations.
Obviously the contribution of these
blade parts to the driving force of the
turbine is negligible.
In the curve of the blade, the speed of
the headwind is high. The angle of
attack of the apparent wind is small almost zero - with the consequence
that the component of the lift force in
the direction of the rotation also nears
zero. Also these parts of the blades do
not contribute to the driving force.
However given to their high speed they
do generate a high level of noise.
This explains why the Darrieus turbine
vibrates heavily, makes a lot of noise
and has a low efficiency.
developers chose an odd number of
blades (3) of a helical shape, making all
changes pass off gradually.
As a result of these design
choices, both vibrations and
noise disappeared! And Turby
showed an excellent efficiency.
The blades of Turby are designed with
a fixed distance to the shaft.
To reduce the inevitable vibrations due
to the change of the angle of attack
between + 200 and - 200 resulting in a
change of the mechanical stress in the
blade two times per revolution, Turby's
Wind is the result of pressure
differences in the atmosphere; the
speed and the direction of wind are
determined by the ratio of the pressure
differences and the distance between
the centres of high and low pressure.
At sufficient height (100 meters) wind
speed and direction will be the same in
a large area. Closer to the ground the
pattern changes due to the resistance
the wind has met on its way.
At ground level wind speed is
practically zero. Depending on the
terrain over which the wind blows,
speed increases faster or slower with
increasing height. A surface of water
offers little resistance and therefore at
little height the wind is already very
noticeable. That's why we always
experience wind on the water1.
In urban or built-up areas the wind is
severely obstructed. There is air
movement between buildings, but that
is turbulence, not wind. Only above the
average building height does the air
"reference height level" for wind in an
urban or built-up area is 10 meters and
Wind speed data are normally collected
at a height of 10 m above ground level
or are converted to that height. On the
basis of the average wind speed at 10m
height, the terrain roughness, and the
geographic location, the expected wind
speed distribution for an intended
turbine placement can be calculated.
Windspeed profiles above different terrain
roughness z0 (and displacement height d) at a
mesoscale wind speed
Um=13.1 m/s at approx. 60m
Note: the terrain roughness is
indicated as the "roughness length" of
the terrain and stated as a measure of
For the Netherlands the KNMI2 has
depicted these data in a "stain chart"3.
The wind speed at a certain location is
determined by the geographical
location, the height and the terrain
With thanks, this figure has been taken from  Wind
Climate of the Netherlands
=Royal Netherlands Meteorological Institute
With thanks, figures have been taken from  Wind
Climate of the Netherlands
The average windspeed:
The wind speed distribution describes
how many hours per year the wind
blows at a certain speed at that location
and at that height. Together with the
power curve of the wind turbine, an
output prognosis for that particular
wind turbine at that particular location
and that particular height can be
N.B. For that reason it makes little
sense to ask what the output of a wind
turbine might be, as this question
cannot be answered simply or in
general terms. Knowledge of precise
wind speed distribution data, at a
proposed turbine height, for a
roughness), is essential to predict the
power output of a wind turbine.
In cooperation with the Institute for
Wind Energy of the Delft University of
Technology the Turby team has
developed a program to calculate the
wind speed distribution at different
heights and terrain roughnesses and
used that to calculate the yield for one
hundred areas in the Netherlands
(distinguished by the first two numbers
of the postcode) based on these data.
As an example the results of these
calculations for a hundred areas in the
Netherlands are depicted in the
diagram above. Note the increase in
annual yield with increasing height,
which is a result of the cube
relationship between wind speed and
Yield as function of postal code and height
Height of tower above earth surface [m]
Wind in built-up areas
In the preceding text the macro
behaviour of wind was discussed.
However, for wind turbines like Turby
the micro behaviour is decisive and
this can deviate significantly.
Wind follows the path of least
resistance by going around obstacles.
Along the edges of these obstacles the
wind speed and the density increase. If
a wind turbine is capable to utilize this
increase in speed and density its
energy production can be up to two
times higher than when standing in an
But placed on the lee side of a big
obstacle, the output will reduce to half
of the yield normally expected.
Since wind turbines for urban areas are
small, averaging does not diminish
these phenomena that consequently
largely determine the yield.
Wind over buildings
Depicted below are the results of
computer calculations showing the
effect of an obstacle on the wind flow
around that obstacle.
The picture below shows the influence
of a long obstacle ( e.g. a building) on
the wind in the vicinity of that obstacle.
Note that the deviations start long
before the wind reaches the obstacle
and continue far beyond it.
This figure makes it apparent that wind
passes at an upward angle of 30 to 40 0
from the leading edge over the roof of
the building. Underneath that line
there is only turbulence and no wind.
For that reason the turbine must be
placed on a mast of sufficient height to
bring it turbine above the turbulence.
But if we do that a potential advantage
arises since the wind speed directly
above the turbulence layer is 20-40%
higher than that prior to encountering
This 20 - 40% higher speed raised to
the cube (1,4 3 = 2,7) offers a 2 - 3
times higher power than the
undisturbed horizontal wind flow. This
is potentially very interesting, provided
that the wind turbine can utilize the
wind approaching from such an angle.
Turby has been designed for just
Prevailing wind direction and
optimal position on the roof.
Turby in the urban or built-up
As explained a wind turbine on a roof
should be placed above the turbulence
Consequently the closer a
turbine is placed to the leading roof's
edge for the prevailing wind the lower
the turbine can be placed. And a lower
mast is advantageous from the
perspective of costs and height
This would be true if the number of
hours the wind blows from other
directions than the prevailing one is
negligible; however in Western Europe
the percentage of time the wind blows
from the prevailing direction as
compared to an equal distribution is
not that prominent.
In the wind tunnel at Delft University
of Technology, the Turby team has
researched the reaction of its wind
turbine to winds approaching from an
angle from below, just as it occurs over
buildings. The pictures below show the
test set up.
& lt; 4 m /s
4 - 1 4 m /s
& gt; 14
The chart above shows as an example
the wind distribution for Schiphol
airport. For the wind speeds relevant to
small rooftop turbines (4-14 m/s
range) the wind is about 35 % of the
time blowing from the south-westerly
quadrant; the remaining 65 % of the
year the winds blows from other
The (only) correct placement is close
to the middle of the roof on a mast
with an approximate height of 5 m or
above. If placed near the prevailing
wind roof edge the yield will be
reduced to about 1/3 of that of a
centrally placed turbine.
The results bewildered the researchers.
Horizontal axis wind turbines reach
their optimum output when the wind
comes in perpendicularly to the rotor.
Turby performed during these
tests as if the wind came in
perpendicularly at its full speed
and showed an aerodynamic
efficiency of close to 40%!
The tests indicate that the energy yield
may well be up to two or more times
higher than expected from the swept
area of the rotor. Horizontal axis wind
turbines cannot take advantage of an
upwardly slanted incoming wind but
suffer from the stronger forces on their
rotors from such a wind.
Whether other vertical axis turbines
can use this effect is unknown; in our
research, no turbines similar to Turby
have been found.
The figure shows a Turby prototype on
top of an apartment building placed
approximately in the center of the roof,
as indicated above.
The forces exercised on Turby and in
turn by Turby on the roof are low. The
chart below shows the relation between
wind speed and force on the turbine.
Generally Turby is placed on a steel
cross frame connected to the roof by
chemical anchors or kept in position by
ballast on its footplates.
Forces on Turby shaft
Forces on shaft [N]
There are two explanations for this
due to the helix-shaped blades
an upward-slanting wind passes
the airfoil perpendicularly in a
nearly ideal way;
as a consequence of the 3-D
character of the Turby rotor
such a wind hits the blades on
the leeside at full speed
delivering extra driving power.
wind speed [m/s]
The easiest type of roof to put Turby on
is a concrete roof; channel plate-,
gasconcrete -, or steel skeleton roofs
generally require positioning of the
fastening points on internal walls or
rafters. Elevator shafts and similar
rooftop structures are very suitable as a
basis for Turby since they offer next to
sufficient strength additional height:
the mast can be shorter reducing the
forces on the roof accordingly.
The building contractor familiar with
its construction is capable to determine
the proper location for the fastening
points. Also the architect who knows
both the building as the local building
legislation can decide about the best
location for a wind turbine.
The Turby team will be glad to supply
the required data and is on demand
available to coordinate between the
The fitting of the fastening points and
the cable throughput on the roof needs
to be done by the roofing contractor to
Turby is supplied with two different
mast types depending on the required
height. Up to 6 m height we supply
spring supported masts and from 7.5 m
onwards freestanding tubular masts.
Examples of both are shown in the
See also the dimensional drawing.
Both types are available in stainless
steel and galvanized.
10 m freestanding stainless steel mast
6 m spring supported galvanized steel
"Vibration" and "resonance" deserve
special attention. Although Turby is
dynamically balanced to a balance
quality of G 6.3 (ISO 1940/I) and
therefore to a large extent vibration
free, it is and remains a dynamic
system that may introduce vibrations
into the building it is attached to.
This occurs when the resonance
frequency of the combination of mast
and roof falls within the operating
frequency range of the turbine, viz 1 10 Hz. In order to prevent adverse
effects due to these dynamic
phenomena we designed the two mast
types having a resonance frequency
just below 1 Hz.
The amplitude of a potential vibration
of the support structure (and building)
is in practice determined by the mass
of the system.
A concrete roof will not pose problems
since its resonance frequency is low
and its mass high. A resonance - if
occurring - will not be noticeable. This
may be different with roof using a steel
skeleton or wood construction. It is
complicated to calculate the occurring
resonance frequencies for these roofs;
measuring is far simpler and cheaper.
Turby can offer you this service.
Turby on family houses
Turby is designed for use on higher
buildings. Calculations show that at
heights from 20 m upwards, a good
yield can be expected. Below that
height the yield is uncertain. A three
storey family house has a height of
about 10 m.
Since the turbine must be situated
above the turbulence layer, a mast of at
least 5 meters is required. The top of
Turby will be at least 8m above the
roof, which - from an esthetical point
of view - is in most cases much too
high for a family house. Furthermore
the roof construction of family houses
is in general too light to withstand the
forces that extreme winds can exercise
and the roof construction may not be
suitable due to vibrations.
Turby is not especially suited for use
on family houses, but apartment
buildings are certainly within its
competitive with traditional electricity
generated from large power plants.
The depreciation period for big power
plants, whether oil-, coal-, natural gas-,
or even nuclear fuelled, is in general 20
years. These plants operate 8000
hours per annum at an average load of
80%; the degree of utilization of the
installed capacity is 73 %. Each kW
generates 6400 kWh p.a. The
investment per kW installed is in
average EUR1500; an investment per kWh
p.a. of EUR 0.24.
Turby has a nominal power of 2.5 kW
and generates in average 3500 kWh
p.a. The investment per kW Turby is
EUR6000 (price level 2005); each kW
delivers 1400 kWh p.a.; an investment
of EUR 4.28.
Conclusion: The financial burden of
Turby per kWh p.a. is 18 times higher
than those of a traditional power
An unbridgeable gap?
The fuel for Turby is free; there is
neither maintenance required nor
personnel to run it. Its operational
costs are nil!
Turby's kWhs do not need to be
delivered to the customer - they are
already there on his roof. No costs for
the use of electricity networks and no
grid losses in those networks. (10 % of
traditionally generated electricity is
lost during transport and distribution).
No administrative, or overhead costs.
In average the sales price of
traditionally generated kWhs is about
ten times the depreciation costs.
or not to be....
Taking that into account, the costs
comparison between Turby kWhs and
traditionally generated electricity is far
better than concluded earlier; a factor
of 1.8 remains. Electricity from Turby
is currently more expensive than
traditional generation, but what will
the future bring? Cost increases as:
rising fuel costs
will effect the costs of traditionally
generated electricity, but not Turby's.
No doubt that these factors will within
a few years change the economics of
power generation in favour of Turby.
And, built in series, the price of Turby
will reduce with about 20 - 40 %.
How will this effect the economy over
Turby's life expectancy of 20 years?
share our view that the stock of
fossil energy is finite and the
first signs of shortage are there;
expect a rapid increase of the oil
price as predicted recently by
adviser of the president of the
USA Mr. G.W. Bush to US$ 200
- 250 a barrel;
recognize the threat that in the
coming decade's wars will be
waged for the possession of the
last barrels of oil;
dare to be a pioneer, to show
your conviction, your green
heart and your innovativeness;
want our children to inherit a
then invest in a Turby.
NL 7241 HZ Lochem
+ 31 573 256 358
Fax + 31 573 254 420
Specification sheet January 2006
Cut-in wind speed
Rated wind speed
Cut-out wind speed
Survival wind speed
Rated rotational speed
Rated blade speed
Rated power at 14 m/s
120 - 400
Weight (inc. blades)
Weight (3 blades)
6 x M10
Peak brake current
3-phase synchronous permanent magnet generator
during 250 ms
4 -quadrants AC-DC-AC
60 Hz in development
Maximum Power Point tracker
Starting is achieved by the generator in motor operation
Electrical, short circuiting of the generator
Grid failure, anti-islanding, system faults, short circuit, mechanical faults, vibrations,
blade rupture, imbalance.
Two independent detection systems each triggering an independant brake action:
- Generator frequency measurement in the converter
- Generator voltage measurement on the generator terminals
HEA 160, galvanised
300 x 280 mm
Other masts and foundations than mentioned in the specification are possible on request
Above specifications are subject to change without prececeding announcement and not binding the manufacturer.
Windklimaat van Nederland
J. Wieringa en P.J. Rijkoort
ISBN 90 12 04466 9
Ris? National Laboratory
Klimatologische gegevens van Nederlandse stations
Publikatie nummer 150-27
Chris Westra en Herman Tossijn
Ekologische Uitgeverij Amsterdam
ISBN 90 6224 025 9
Wind Energy Explained
Manwell, McGowan & Rogers
John Wiley & Sons Ltd
ISBN 0 471 49972 2
Price indication Januari 2006
Turbine with convertor
turbine - mast connection box
transport & packaging
? EUR15,83 pro m
cabling between connection box and converter
supply of throughput in stainless steel
labour: Drilling of hole ? 50 x 100 mm max.
Civil works calculation of roof loads
site inspection and consultancy (travel time included ? EUR126,50
travelling costs and expenses
Above prices are
valid for EC countries
and only binding with our order acceptance.
We expect to be able to present more competitive alternatives for the 5 and 6 m mast within a few months,
Other masts than mentioned in the price list are possible on request.