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the Betz Limit
For the same swept area (by a wind turbine), the wind energy
captured by the sail-shaped body of the Saphonian is twice as
higher as that of conventional wind turbine. By replacing the
blades' rotor by a compact sail-shaped body (curved) that
enjoys high aerodynamic coefficients (Cl and Cd), the
Saphonian has set itself free from the insurmountable Betz
Empirical performance tests have shown that the Saphonian
efficiency level is 2.3 times as high as that of the bladed
wind turbine on account of the following:
- For the same swept area (by a wind turbine), the wind energy
captured by the Saphonian is twice as higher as that of
conventional wind turbine.
- The Saphonian has eliminated most of aerodynamic and
mechanical losses, originally due to the use of blades and
gearbox and to the characteristics of the rotational motion.
Over the last two years, Saphon’s team has designed, developed
and tested number of operating prototypes. The latest
empirical tests made on a 300-500 Watt prototype (diameter of
120 cm) confirmed and validated the theoretical assumptions.
This allowed us to optimize the initial design and further
improve the hydro-mechanical performance. A second generation
prototype is under tests.
Sail-inspired turbine promises cheaper wind energy
The sail-inspired wind turbine may capture more
[TUNIS] A Tunisian invention that harvests
wind energy through adesign inspired by sailboats promises
cheaper, more efficient wind energy.
The bladeless wind turbine, the Saphonian, named after the
wind divinity that was worshipped by the ancient
Carthaginians, also promises to be more environmentally
friendly than existing wind turbines that produce noise and
kill birds through their blade rotation.
Instead of rotating blades, the Saphonian's sail-shaped body
collects the kinetic energy of the wind, Anis Aouini, the
Saphonian's inventor, told SciDev.Net.
He explained that the resulting mechanical energy moves
pistons which generate hydraulic pressure that can be stored
in a hydraulic accumulator or converted into electricity.
"This is not the first bladeless wind turbine, but we thought
outside the box: the initial idea came from sails — the only
human system that can capture and convert the bulk of the
wind's power into mechanical energy," said Aouini.
An average wind turbine captures only 30 to 40 per cent of the
wind's kinetic energy, while the Saphonian can capture up to
80 per cent, according to Aouini.
Hassine Labaied, chief executive of Saphon Energy, the
start-up energy company established to get the turbine to
market, said the Saphonian reduces the aerodynamic and
mechanical energy losses associated with rotating-blade
"Our second generation prototype is 2.3 times more efficient,
and costs nearly half the price of its predecessors
[conventional wind turbines]. It discards the most expensive
components in a traditional wind turbine, which are the
blades, hub and gearbox," said Labaied.
Aouini and Labaied patented the technology in Tunisia in
September 2010, and received an international patent in March
2012. Saphon Energy is now looking for a partnership with a
manufacturer to deploy the technology worldwide.
"We are negotiating with a number of international companies
that produce renewable energy technology, and will finalise
this by the end of this year," said Labaied. He estimated that
it would take up to two years until the commercial product
reaches the market.
Ali Kanzari, a renewable energy expert and director-general of
Solar Energy Systems, told SciDev.Net that the Saphonian
"seems to be a radical and economically viable alternative to
bladed turbines". However, he added that "the manufacturing
step is important as it will determine how the market will
"The electricity produced through wind in Tunisia represents
five per cent of total electricity production in the country,"
Ayadi Ben Aissa, former chief executive of the Tunisian
Society of Electricity and Gas (STEG), told SciDev.Net.
He said that using the Saphonian technology could produce up
to 20 per cent of Tunisia's electricity from wind in the
SYSTEM FOR CONVERTING WIND ENERGY
Inventor: AOUINI ANIS M
Applicant: SAPHON ENERGY LTD
The invention consists of a system for
converting wind energy (SCEE) into mechanical and then
electrical energy. This system (SCEE) is not subject to the
theoretical Betz limit (59%). The system (SCEE) has a wheel
(F) equipped with a series of blades arranged all around it.
The wheel (F) turns in a pivoting connection about a fixed
axle (L). Set on the axle (L), a support (E) attaches the end
plates of a series of double-acting actuating cylinders (D).
The cylinder rods of the latter are in a ball jointed
connection with the body (A), the purpose of this being to
offer the latter a maximum degree of freedom in space. A rigid
arm (C) is set on one side of the wheel (F) and held on the
other side, in a pivoting connection, on a U-shaped section
piece (B). Having a circular satellite movement, the latter
turns with the wheel (F) while at the same time sliding over a
peripheral region of the body (A). When the wind blows against
the body (A), the latter pivots with the section piece (B) and
pushes on the cylinder rods of the actuating cylinders (D).
Having a circular satellite movement, the section piece (B)
turns, sliding over a peripheral region of the body (A), thus
changing the fulcrum of the moment of the resultant force of
the wind (the pivot connection of the section piece (B))
applied to the body (A). The cylinder rods of the actuating
cylinders (D) will therefore be pulled and pushed, while at
the same time having a cyclic translational movement. Set on
the axle (L), and a nacelle (J) chiefly contains a hydraulic
motor (H) and an electric generator (G), which can be coupled
via a speed multiplier. During the reciprocating movements of
the pistons of the actuating cylinders (D), a set of valves
allows for a one-way flow of hydraulic fluid inside "out and
back" hydraulic circuits either by pulling or pushing. The
"out and back" hydraulic circuits are also connected to the
hydraulic motor (H). To keep the system (SCEE) always facing
into the wind and allow it to pivot on the mast (1), it can be
orientated by a tail vane (K) which is fixed, via a support,
to the nacelle (J).
The invention description about this technique, is a system
for converting wind energy (CESG) into mechanical energy and
This system of conversion of wind energy (CESG), described
below, is not subject to the theoretical limit of Betz (59%).
Therefore, this invention provides a performance much higher
than wind turbines currently in use.
System (WECS) has a wheel (F) with a series of blades arranged
around (see drawing N [deg.] L).
The wheel (F) is rotated in association pivot about an axis
(L) fixed, thanks to the kinetic energy of the wind through
the blades, providing the wheel (F) a mechanical energy of
Flush to the axis (L), a holder (E), rigid enough, secures the
plates (or the rear end) of a series of double-acting
The latter may consist of one or more double-acting cylinders
(see drawing 1M [deg.]1).
To simplify the present description, the system (WECS) has a
series of three double-acting cylinders.
Distribution and positioning of the series of double-acting
cylinders (D) on the bracket (E) to be assured of a
well-defined way to ensure a better functioning (See detail N
[deg.] The drawing N [ deg.] l).
The piston rods of the plurality of double-acting cylinders
(D) are connected with the ball joint housing (A) and that, in
order to provide the latter with a maximum degree of freedom
in space, allowing one movement and a more fluid into the wind
(See detail N [deg.] the drawing N [deg.] l) & (drawing N
Said body (A) has a shape and surface property determined,
respectively to achieve a drag coefficient higher and a
maximum resultant force of wind captured.
In addition, the body (A) must have the lightest weight
For this case, and not limited to a portion of its surface may
be, for example, covered with veil (See drawing N [deg.]2).
In order to allow the wheel (F) to rotate freely and
independently of the body (A), its active surface (the surface
facing the wind) is kept constantly exposed to the wind (see
the front views of the drawings N [deg.]3, N [deg.]4, N [deg.]
5 & ??N [deg.]6).
The mountings of the piston rods of the double-acting
cylinders (D) on the body (A) to be set at the axis which
coincides with the direction of the vector of the resultant
force of the wind attacks the body (A) (See detail N [deg.]
the drawing N [deg.] l).
A rigid arm (C) is recessed from one side to the wheel (F) and
maintained on the other side, pivotally connected to a profile
(B) U-shaped With a circular motion satellite, it turns,
therefore, with the wheel (F) while sliding on a peripheral
area of ??the body (A) (See drawing N [deg.]2).
In order to minimize the friction of the sliding profile (B),
the latter may be in contact with the sides of the peripheral
area of ??the body (A) via the rollers or the like.
In addition, the peripheral area of ??the body (A) must be
smooth enough and stiff enough.
When the wind acts on the body (A), the latter rotates under
the effect of the moment of the resultant force of the wind,
as with that of the pivot section (B) and the body (A) grows
without jamming through bonds ball, the stems of double acting
cylinders (D) that are present in the area diametrically
opposite the rail (B).
The rods double acting cylinders (D) present in the reverse
zone (zone side of the profile (B)) tend to be drawn (see
drawing IM [deg.]3).
Having a circular satellite movement, the profile (B) is
rotated while sliding on a peripheral area of ??the body (A),
thereby changing the pivot point of the resultant force of the
wind (the pivot connection of the profile (B)) which s'
applied to the body (A).
The rods double acting cylinders (D) will, therefore, drawn
and pushed, while having a translational movement cycle (See
drawings N [deg.]3, N [deg.]4, N [deg.]5 & ??N [deg.]6).
Thus, wind energy captured by the wind body (A) is converted
into mechanical energy of translation of the piston at the
double-acting cylinders (D), thus creating pressure on the
The views from the front, left, top and perspective drawings N
[deg.]3, N [deg.]4, N [deg.]5 & ??N [deg.] 6 show the
action of the body (A) on the stems of double-acting cylinders
(D) as well as the behavior of the system (WECS) upwind for
different positions (0 [deg. ], 90 [deg.], 180 [deg.] &
270 [deg.]) of the profile (B) on the peripheral area of ??the
A nacelle (D) is embedded to the axis (L).
This platform (J) contains mainly a hydraulic motor (H) and an
electrical generator (G), which can be coupled via a speed
multiplier (See drawing N [deg.] L).
During the back and forth movements of the pistons series
double acting cylinders (D), they grow hydraulic fluid to the
hydraulic circuit path (in red) convertible to either pulling
or pushing, and through a set of valves (see drawing N
The latter also allows to suck the hydraulic fluid in the
double effect cylinders (D) through the hydraulic return
circuit (blue) and, in single direction "regardless of the
motion by pulling or pushing."
The hydraulic circuit of the aisle (red) is connected to the
input of a hydraulic motor (H).
The back (blue) is also connected to the output of the
hydraulic motor (M) (see drawing N [deg.]7).
Thus, the flow of hydraulic fluid under pressure, is converted
into a rotational movement of the motor shaft (H), which is
connected to the axis of the electric power generator (G) via
a speed multiplier, generating so clean electricity (see
drawing N [deg.]7).
To allow for the wind direction kept the system (WECS), can be
equipped with a system of automatic orientation allowing it to
pivot on the mat (i) and keep the body (A) and the wheel (F )
continually face the wind, and this mode upstream or
In addition, the orientation can be achieved using a rudder
(K), well-defined dimensions, fixed through a medium, the
nacelle (J) (see drawing N [deg.] L).
In order to simplify the operation of the orientation system
(WECS) and not limited to the solution of the rudder (K) is in
this case taken as illustrative example.
Thus, wind energy captured by the body (A) is converted into
mechanical energy of translation and rotation, respectively,
via the rods of the set of cylinders (D) and the hydraulic
This mechanical energy is then converted into electrical
energy with the electric generator (G).
The link in this chain of energy conversion on the conversion
of mechanical energy into mechanical energy of translation of
rotation can be insured without limitation, via several other
mechanisms such as crank-connecting rod or other ...
As announced at the beginning of the technical description,
the system (WECS) is not subject to the theoretical limit of
Betz (16/27%) and provides a better yield of wind energy
The only component subject to the Betz limit, is that the
wheel (F) which has only a small surface area compared to the
total active surface system (WECS).
In addition, this wheel (F) only serves to change the position
of the profile (B) in a circular motion satellite and the
energy it captures is not required to consider the chain of
energy conversion described above, or in the final recovered
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