"Compact-combined solar-wind system with whirling uptake of winds at altitude for electricity production"

The wind generators in operation for past twenty years certainly display a critical technology issue due to the considerable encumbrance of the generator and the multiplier unit arranged on the heavy gondolas at the top of the towers, and for the massive support work that this kind of structure require in terms of structural foundations, all engendering high costs.

The heavy environmental impact due to the increasing size of the machines is also undeniable. Currently, many wind farms have already reached the end of their life cycle and many others are gradually reaching it over time, subjecting companies in the sector to a serious problem of management costs not only for the disposal of the plants but above all for the obligation of restoration and reclamation of sites. The technologies available today are not compatible with the old structural foundation systems and therefore the latter cannot be recycled. The issue of decommissioning wind farms involves the burden of having to deal with a very complex issue also from the point of view of costs, to such an extent that this represents a factor for serious reflection on the whole wind power issue.

The project, which was specifically designed to deal with this complex problem, also solves the production gap of traditional wind power, by integrating in a single machine a technological system capable of exploiting both the action of wind and the conversion of light and solar radiation. The integrated system, subject of this invention, exploits recent developments in photovoltaic solar panel technology involving panels that are thin but highly efficient in converting solar power to electricity (almost double compared to amorphous silicon).

The idea of using the large surface of the tower as a photovoltaic field undoubtedly solves the environmental impact problem typically associated with the system and allows a significant increase in energy production compared to normal wind generators. Moreover, the flexible photovoltaic panels that cover the external surface of the tower have an enhanced conversion effect compared to the traditional photovoltaic system. The effect is due to the reflection of the light and solar radiation increased by a system of focusing mirrors suitably positioned around the base of the tower. The outer surface of the tower is cooled, using the Ranque effect, by a stream of air conveyed inside by the Coanda effect.

The cooling system, produced by exploiting the physical effect on the external surface of the tower, solves the problem of excessive heating due to solar radiation induced by the focusing mirrors. The heat exchange between the photovoltaic panels and the airflow in the conduit increases the temperature of the flow itself, increasing the axial speed and consequently the kinetic energy. A turbine-alternator located at the base of the conduit converts the high fluid-dynamic energy into electrical energy.

The tower is made with a supporting paraboloid metal frame with a static conveyor at the top that acts as an air duct designed for conveying the wind at high altitude. The swirling motion of the wind inside the conduit favours the formation of a low-pressure vortex above the flow collection system which, as a result of the physical effect, leads to the wind current at altitude being diverted and retrieved, increasing its speed and hence energy potential.

By exploiting physical phenomena such as the Ranque effect and the Coanda effect, the inside of the conveying conduit favours the formation of a cooler airflow compared to the conduit inlet wind. At the top of the conveyor an air vortex is generated which, due to the Ranque effect, is therefore colder in the central area, while the Coanda effect induced by the wind fraction conveyed in the conduit groove, between a support disk and a vortex, feeds the cooler air flow to the turbine located in the lower end of the conduit.

In practice, the Coanda effect, which is generated in the area where the air passed through the conveyor, induces a Ranque reverse flow effect, compared to industrial systems and equipment that exploit this physical phenomenon for air-cooling.

The specific axial intake turbine with tangential output converts the kinetic energy of the flow into electrical energy by means of the alternator directly fitted to it.

Adopting this technological solution and a diversion gradient for the wind at altitude, it is possible to obtain remarkable fluid dynamic powers with modest height dimensions respect to traditional wind farms. Vertical height can be reduced up to 1/5 of the wind generator towers currently in use.

Figure 1 shows the flow lines W (Ref. 1) of the wind current affecting the numerous collection elements (Ref. 3), fixed and arranged in an equidistant manner under the annular support disc (Ref. 2).

The vanes (Ref. 4) direct the intercepted wind flow towards the collection conduit (Ref.5), which, having a convergent longitudinal section, accelerates the airflow along the passage to the outlet end where the static flow cylindrical rectifier is placed (Ref. 7).

At the outlet of the cylindrical flow rectifier (Ref. 7), the very fast fluid current is almost parallel to the vertical axis YY. The cross-sectional area of the cylindrical flow rectifier (Ref. 7) is much smaller than the inlet section of the upper end of the collection conduit (Ref. 5) which collects the flow coming from the vanes (Ref. 4). At the outlet of the cylindrical flow rectifier (Ref. 7), the axial fluid current enters the turbine (Ref. 8), whose particular conformation induces rapid rotation.

From the turbine (Ref. 8) the flow u, which has lost a part of its kinetic energy, comes out tangentially (Ref. 15 - Fig. 3). All the fixed static system, consisting of the collection elements (Ref. 3), the vanes (Ref. 4) and the collection duct (Ref.5), are supported by several axes (Ref. 11) rigidly connected between the annular disk (Ref. 2) and the base and support platform (Ref. 12) anchored on the foundation supports (Ref. 13).

At the top of the base and support platform (Ref. 12) the support brackets are arranged in an equidistant way (Ref. 14), on which the parabolic mirrors can oscillate (Ref. 9) housed with their respective position pins (Ref. 10).

The only dynamic component of this complex structure is the turbine (Ref. 8), which causes the alternator, fitted directly onto the turbine itself, to rotate rapidly.

Figure 2 illustrates in more detail the different components of the specific wind power generation system integrated with the latest generation flexible photovoltaic panels (Ref. 6 - Fig. 1 and Fig. 2) that cover the collection conduit (Ref.5).

The entire collection conduit (Ref. 5) is covered with latest-generation flexible photovoltaic panels with a high electricity conversion rate (Ref. 6 - Fig. 1 and Fig. 2). The only critical factor of this type of photovoltaic panels is represented by the rise in temperature during prolonged operation, a temperature rise that would be exclusively due to the high conversion yield that is solved by the fact that the solar panels come into direct contact with the metal wall of the conduit characterised by a level of high thermal conductivity and cooled by the continuous flow of cold air coming from above with increasing speed and directed downwards in the turbine (Ref. 8 - Fig. 1).

The solar panels (Ref. 6 - Fig. 1 and Fig. 2) are not irradiated directly by sunlight (Ref. 16), but receive radiation (ref. 17) concentrated and reflected by parabolic mirrors (Ref. 9 - Fig. 1 and Fig. 2) adjustable with ± b angle by means of a special control and monitoring device suitable for optimising energy conversion.

Figure 3 represents the particular turbine (Ref. 8) with upper entry along the YY axis coming from the cylindrical static flow rectifier (Ref. 7) of diameter d. The numerous curvilinear and equidistant blades (from 6 to 16), wound and inclined at an angle Q on the outer mantle with parabolic profile in section and, have a constant diameter D much greater than d in the lower end part of section /, thus allowing the tangential exit of the stream u (Ref. 15).

This specific conformation means the turbine (Ref. 8) rotates the central shaft very quickly (Ref. 18) on which the alternator is fitted directly, without the aid of a speed multiplier. By virtue of this specific geometric configuration of the turbine (Ref. 8), due to the higher speed of axial intake, it is possible to achieve high electrical energy yields, since the alternator and the turbine are directly coupled.

This type of direct coupling is not feasible with traditional generators that are characterised by low rotor revolutions, and therefore, in order to obtain high torques and powers, they need specific revolution multipliers that are a major critical factor, calling into question yields, reliability and weights.

Figure 4 illustrates in more detail the orientation system of the numerous parabolic mirrors (Ref. 9 - Fig. 1, Fig. 2 and Fig. 4), mounted on the base platform and support (Ref. 12 - Fig. 1 and Fig. 4). Each parabolic mirror (Ref. 9 - Fig. 1, Fig. 2 and Fig. 4) is able to orient itself by rotating through its own angle b on the position pin (Ref. 10 - Fig. 1 and Fig. 4) which connects the parabolic mirror itself to the mobile (Ref. 25) and fixed supports (Ref. 14) placed on the base platform and support (Ref. 12 - Fig. 1 and Fig. 4). The control and monitoring of each parabolic mirror (Ref. 9 - Fig. 1, Fig. 2 and Fig. 4), which reflects solar radiation (Ref. 17) sending it to the different solar panels (Ref. 6 - Fig. 1 and Fig. 2), is achieved by means of a particular device (Ref. 19) in which a special lens captures the sun's rays (Ref. 16) and identifies the instantaneous inclination angle a with respect to the zenith. The device (Ref. 19) sends the encoded data to the processor-actuator (Ref. 20), which, based on the values of the angle a detected, moves the lever (Ref. 22) which moves the position pin axially (Ref. 10 - Fig. 1 and Fig. 4).

The central part of the position pin (Ref. 10 - Fig. 1 and Fig. 4) consists of a multi-start (from 3 to 6) screw coupled with the respective rigid nut screw on the mobile supports (Ref. 25). Each axial displacement value of the position pin (Ref. 10 - Fig. 1 and Fig. 4) corresponds to a specific angle b of the parabolic mirror (Ref. 9 - Fig. 1, Fig. 2 and Fig. 4).

The monitoring and control system of the individual parabolic mirrors automatically achieves the best irradiation condition for the solar panels (Ref. 6 - Fig. 1 and Fig. 2) for each position of the sun during the day. The conspicuous extension of the surface of the panels covering the collection conduit (Ref. 5 - Fig. 1) and the high degree of electrical conversion associated with the great efficiency of the wind turbine, make this innovative integrated system capable of producing power to the order of a few MW despite the very low height of the tower compared to the gigantic towers that the wind production system currently employs.

The reduction in the overall height dimensions of the tower up to 80% is an appreciable factor in reducing the environmental impact. The total absence of long blades and the use of the photovoltaic system built into the large external surface of the tower makes this system very compact with very low visual impact.

This project's characteristic system lends itself in particular to the development of intensive farms as, unlike the traditional ones which require safety distances between the towers to guarantee fluid dynamic efficiency, placing it in an intensive formation increases the production capacity due to the effect of the greater fluid-dynamic depression generated at the top of the towers as a result of the specific technological characteristic of the air flow cavitation system. From the construction point of view, the absence of revolution multipliers makes the technological solution of direct coupling between wind turbine and alternator much more effective and reliable over time from an operational point of view and makes the manufacturing process significantly more cost effective.

Figure 5 provides a schematic representation of the computer controlled and managed integrated solar-wind system (Ref. 32).

The electricity produced by the numerous solar panels (Ref. 6 - Fig. 1 and Fig. 2) is sent to the inverter (Ref. 28). The alternator (Ref. 26), fitted directly to the turbine (Ref. 8 - Fig. 3) by means of the turbine shaft (Ref. 18 - Fig. 3 and Fig. 5) send the electrical energy generated at alternating current in the inverter (Ref. 27). Both inverters are connected to a management device (Ref. 29) that receives electrical energy converted into alternating current. The management device (Ref. 29) send the alternating current to the distribution panel (Ref. 31) through the electrical line (Ref. 30).