GENERATOR" DESCRIPTION

Field of application

[0001] The present invention relates to floater for the support of an of fshore wind power generator .

[0002] Advantageously, in addition to devices for exploiting wind energy, systems for generating electricity from other renewable sources , such as waves , sun, underwater currents , for example , can also be installed on board .

[0003] In particular, the floater in accordance with the invention is intended to be used in waters with depths exceeding 40m .

Background art

[0004] Wind farms on seacoasts for exploiting clean renewable energy, extractable from the wind, are a well- known and long-established reality and contribute to the reduction of pollution of various kinds , caused by the indiscriminate use of fossil fuels .

[0005] In a context of increasing energy production from renewable sources , production from wind sources plays a fundamental role , for both terrestrial and marine implementations thereof . However, the inconvenience associated with installing wind turbines on land and essentially linked to the impact on the landscape and noise pollution leads to moving such installations away from the most densely crowded areas , which however also appear to be the most energy hungry, moving them on sea on the coastal area, where possible .

[0006] The present technology for exploiting wind power in the marine industry is limited by the availability of suitable coasts and by the threshold depths of about 50 m beyond which the present technology of poles or pylons fixed into the seabed is halted .

[0007] The availability of suitable sites , as described above , is gradually decreasing . Furthermore , the availability of energy to be extracted from the wind is much higher moving of f the coast in deeper waters , but also more hostile from the point of view of weathermarine conditions .

[0008] On the one hand, moving away from the coast will entail higher costs , but on the other it will ensure enormous wind power potential . For example , in the seas of Northern Europe , the intensity of the wind on the high seas is 35-50% greater than on the coast ; this means double the energy available , since the latter is proportional to the cube of the wind speed .

[0009] Such a situation requires searching for new technical solutions which allow extending of fshore wind power farms in areas which, until recently, were considered unusable from the point of view of available technical means and from the economic point of view .

[0010] Proposals for floating means of various kinds and shapes have been recently put forward, but , due to various technical/constructional and/or installation and/or maintenance complications , they are general ly unattractive from the economic point of view .

[0011] A recent and authoritative statistic indicates that the installation cost of a wind power generator fixed to the seabed is about 4-5 USD/MWh and the equivalent cost for the of fshore floating solution is about 6 USD/MWh . There is therefore the need to actively seek appropriate technical and production solutions which make floating installations less expensive . According to TEA data, global average upfront capital costs for of fshore wind power ( including transmission) are proj ected to decline to below $2500/ kW by 2030 , more than 40% below today' s average . This is based on the assumed learning rate which sees capital costs decline by 15% each time global capacity doubles . By 2040 , it is proj ected to fall to $ 1900/ kW .

[0012] At the moment there are only a few prototype experiments installed of fshore in various parts of the world (Norway, USA, Japan) which aim to demonstrate the effective seakeeping and economic convenience of various design proposals which are conceptually very different from one another.

[0013] The technical solutions of the suggested floaters vary according to the depth and the weather-marine conditions which they address.

[0014] There are different types of floating wind power platforms inspired by the offshore Oil&Gas industry. These are supported by floating structures, with 6 degrees of freedom, which can be energized by wave loads, wind and ocean currents. The whole system must then be moored and stabilized using mooring lines, ballast, or large waterline areas.

[0015] The main concepts for floating platforms are: Spar- Buoy, Semi-submersible and Tension Leg Platform (TLP) , in addition to those of the Barge type.

[0016] Spar-buoy

[0017] Spar-buoy technology SP (diagrammatically shown in Figure 1) has a simple design, characterized by a very slender cylindrical structure, designed to ensure high transparency to the waves, being mainly intended for the North Seas, which are very energetic seas, characterized by high waves. Such a type, having a small floating area and therefore a very low metacentre (the metacentre geometrically is the point about which the line of action of the hydrostatic thrust rotates due to the small inclinations of the float ) , is stabili zed with ballast at the base so as to lower the centre of gravity G thereof and increase the metacentric height GM thereof ( distance between the centre of gravity G and the metacentre M) so as to ensure suf ficient stability . It is typically simple to fabricate , but the great depth requirements can create logistical challenges during assembly, transport and installation, and can limit the use thereof to sites deeper than 100/200 m .

[0018] The technical issues associated with this type of floater are the di f ficulty of constructing the spar-buoy, which requires shipyards with a great launch depth, and the subsequent complexity of towing it to the final site and completing it with the installation of the turbine on the high seas , activities which are technically di f ficult and expensive .

[0019] Such aspects make the use thereof in wind farms consisting of a large number of floaters , as provided for by the wind farms soon to be installed, complicated and industrially inef ficient .

[0020] Semi-submersible platforms

[0021] Semi-submersible platforms S are platforms which float semi-submerged on the surface of the sea, as diagrammatically shown in Figure 2 ) . In fact , they are characteri zed by a part of the hull being immersed to ensure the necessary hydrostatic thrust and by a part being emerged, usually supported by thin columns connected to one another by arms , which exert the correct stabili zing lever and a suf ficient transparency to wave motion, as shown in Figure 3 . The righting moment depends on the surface of each column and on the mutual distance . Increasing the floating area, thus reducing the total si ze of the unit and the consequent construction complexity, means increasing the response of the floater to hydrodynamic forces and therefore greater movements hindering turbine performance , as increasing the distance between the columns improves the overall performance at the expense of constructability .

[0022] This results in the need for a large and heavy structure to maintain stability, often made of steel with high structural weight and with manufacturing complexity due to the many welded connections .

[0023] In general , a semi-submersible platform is a versatile structure by virtue of the non-extreme immersion, as for the Spar-Buoy, and of the flexibility to adapt to the sea conditions of the site . However, these platforms are the most complex from a constructional point of view and therefore require more time and higher costs to be manufactured as compared to the others . For a shipyard, this type of hull presents some executive di f ficulties due to the fragmentation of the components , mainly pipes , when compared with typical shipbuilding carpentry constructions based on preferably flat reinforced metal sheets . Such a geometry also makes the inspection and maintenance step, as well as any restoration work, complex .

[0024] Similarly to the Spar-buoy type , also in this case , the operational and launch immersions do not usually allow for the completion of the set-up within the shipyard and the subsequent towing of the complete vessel to the final site .

[0025] Tension Leg Platform ( TLP )

[0026] TLP platforms have a semi-submerged floating structure , anchored to the seabed with taut mooring lines which provide the necessary lateral stability, as diagrammatically shown in Figures 4 and 5 . This design increases stress on the legs and on the anchoring system, thus generating design, production and implementation complexities . The installation proces s is also more complex, and in addition the operational risks are greater in the event that a leg fails . As compared to other technologies , more complex and expensive moorings are therefore required, although they are shorter in length . [0027] The TLP solution, although it of fers attractive ef ficiency expectations in terms of relative constructional simplicity, on the other hand, is characteri zed by maj or di f ficulties related to the lack of stability thereof during the step of being trans ferred to the final site and until the moorings are permanently positioned and tensioned .

[0028] [ 00028 ] The costs , times and technical di f ficulties when mooring on the final site make this type unattractive considering the large numbers required by the next Wind Farms , which are characteri zed by large numbers of floaters .

[0029] Barge platform

[0030] The barge platform B ( an example of which is diagrammatically shown in Figure 6 ) is a shallow-draft floater, made of concrete or steel , held in position by a catenary mooring . It is the floater solution which, of all , provides the maximum floating area, and therefore the best stability, but also the maximum exposure to the force of the waves . Therefore , it is suitable for areas which are not very exposed and with low energy seas and low waves .

[0031] An interesting quality of this type of floater is the relative simplicity of construction and the low immersion which allow the completion thereof at the shipyard and then a simple towing to the final site as well as an easy mooring to the predisposed lines ; furthermore , typical shipbuilding construction also makes the inspection and maintenance step, as well as any restoration work, cost-ef fective . These features make the barge platform suitable for mass-production with large numbers and with ease of set-up at the construction plant . However, the Barge type is suitable for areas characteri zed by limited wave motion and depths over 40 m .

[0032] Due to the speci fic conditions of the marine installation site and the weather-marine situations (wind intensity, wave period and height ) , one type of floater can be more convenient than another one . Each structure has its own advantages and disadvantages , which make it preferable depending, for example , on the depth of the sea or the distance from the coast ( for some platforms the greatest di f ficulty is transport to the site ) .

[0033] In any case , in addition to the performance features of each individual type of floater, it will also be necessary to take into consideration, in the immediate future , the industriali zation qualities , so as to meet market demands .

[0034] In the light of the features of the floating platforms known up to now, in the field of floating wind power platforms, the need to have a floater which satisfies the following needs is strongly felt:

[0035] - Simple and therefore cost-effective construction, in line with the typical methods of the large shipbuilding industry;

[0036] - Construction and logistic methods which can be industrialized and allow responding to the immediate demands of the market for having large numbers of largesized floaters within a very limited time span;

[0037] - Limited immersions, such as to allow both the complete set-up at the shipyard and the use of the vessel also in sites with depths starting from 50m to expand the market thereof;

[0038] - Stability of the complete floater during the step of towing it to the anchoring site.

[0039] - Simple and quick on-site mooring, to make the entire process preceding the production of energy by the floating unit cost-effective (i.e., the so-called CAPEX) . [0040] - Reducing and simplifying costs and maintenance operations of the unit during the operational life (i.e., the so-called OPEX) .

Overview of the invention

[0041] Therefore, it is the main object of the present invention to eliminate or at least mitigate the drawbacks of the prior art cited above, providing a floater for the support of an of fshore wind power generator which has limited immersions typical of conventional floaters of the barge type , such as to allow both the complete set-up at the shipyard and the use of the vessel even in sites with depths starting from 50m, while being less subj ect to motions induced by weather-marine conditions as compared to conventional floaters of the barge type .

[0042] It is a further obj ect of the present invention to provide a floater for the support of an of fshore wind power generator which has construction costs comparable to those of conventional semi-submerged floaters of the barge type and is therefore simple and cost-ef fective to build with the typical methods of the large shipbuilding industry .

[0043] It is a further obj ect of the present invention to provide a floater for the support of an of fshore wind power generator which allows carrying out the necessary maintenance operations on the unit during the operational li fe in a simple and inexpensive manner .

Brief description of the drawings

[0044] The technical features of the invention according to the aforesaid obj ects can be clearly found in the contents of the claims hereinbelow and the advantages thereof will become more apparent from the fol lowing detailed description, given with reference to the accompanying drawings which show one or more embodiments thereof merely given by way of non-limiting example , in which :

Figure 1 shows a diagrammatic view of a conventional floater of the spar-buoy type for the support of an of fshore wind power generator, shown in the condition thereof in which it is anchored to the seabed;

Figure 2 shows a diagrammatic view of a conventional floater of the semi-submersible type for the support of an of fshore wind power generator, shown in the condition thereof in which it is anchored to the seabed;

Figure 3 shows a perspective view of a conventional floater of the semi-submersible type for the support of an of fshore wind power generator ;

Figure 4 shows a diagrammatic view of a conventional floater of the TLP type for the support of an of fshore wind power generator, shown in the condition thereof in which it is anchored to the seabed;

Figure 5 shows a perspective view of a conventional floater of the TLP type for the support of an of fshore wind power generator ;

Figure 6 shows a diagrammatic perspective view of a conventional floater of the barge type for supporting an of fshore wind power generator ;

Figure 7 shows a perspective view of a floater according to a preferred embodiment of the invention, with some parts removed to better highlight others ;

Figure 8 shows a lateral orthogonal view of the floater in Figure 7 , shown partially sectioned at the hull according to the cross-section plane VI I I - VI I I indicated in the plan view in Figure 10 ;

Figure 8a shows the lateral orthogonal view of an enlarged detail of Figure 7 relating to the hull of the floater ;

Figure 8b shows an enlarged detail of Figure 8 relating to the hull of the floater ;

Figure 9 shows an orthogonal top plan view of the floater in Figure 8 , shown without the wind power generator ;

Figure 10 shows an orthogonal plan view of the floater in Figure 8 , sectioned according to the crosssection plane X - X indicated in Figure 8 ;

Figure 11 shows an orthogonal plan view of the floater in Figure 8 , sectioned according to the crosssection plane XI - XI indicated in Figure 8 ;

Figure 12 shows a perspective view of only the hull integrated with the covered main deck of the floater in Figure 7 ;

Figure 13a diagrammatically shows the geometry of a conventional floater o f the barge type , while Figure 13b shows the hydrostatic thrust diagram of such a floater in a qualitative manner ;

Figure 14a diagrammatically shows the geometry of a conventional floater of the semi-submersible type , while Figure 14b shows the hydrostatic thrust diagram of such a floater in a qualitative manner ; and

Figure 15a diagrammatically shows the geometry of a floater in accordance with the invention, while Figure 15b shows the hydrostatic thrust diagram of such a floater in a qualitative manner . Detailed description [0045] With reference to the accompanying drawings , reference numeral 1 indicates as a whole a floater according to the invention for the support of a hori zontal-axis of fshore wind power generator . The hori zontal-axis of fshore wind power generator supported by floater 1 will instead be indicated with 100 .

[0046] Here and in the following description and the claims , reference will also be made to the floater 1 in a use condition . In thi s sense , therefore , any reference to a lower or higher position, to a hori zontal or vertical direction, or to an emerged or immersed condition must be understood .

[0047] The floater 1 for the support of a hori zontal-axis of fshore wind power generator 100 comprises a hull 10 which in plan has a closed annular shape .

[0048] As shown in particular in Figures 7 , 8 and 8b, the hull 10 is defined by :

[0049] - a double watertight bottom 20 which follows the closed annular shape of said hull 10 and in use is completely immersed; and

[0050] - a plurality of columnar watertight compartments 31 , 32 , 33 extending vertically from said double watertight bottom 20 at predefined distances from each other along the annular extension of said hul l and which are partially immersed in use .

[0051] The hull 10 can have any closed annular shape . Preferably, the closed annular shape is of the polygonal type , for example triangular, square , rectangular, hexagonal . In accordance with a particularly preferred embodiment , which will be described below, the hull 10 has a closed annular triangular shape .

[0052] By virtue of the closed annular shape of the hull 10 , the floater 1 delimits a moon pool 2 .

[0053] Preferably, i f the hull has a closed annular shape of the polygonal type , the watertight columnar compartments 31 , 32 , and 33 are positioned at the vertices of the polygonal shape .

[0054] The floater 1 further comprises a covered main deck

40 which : [0055] - in plan it has a closed annular shape,

[0056] - structurally connects one to another the vertical columnar watertight compartments 31, 32, 33 above, and [0057] - it is completely emerged in use.

[0058] Preferably, as shown in particular in Figures 7, 8 and 8b, the covered main deck 40 has a closed annular shape corresponding to the closed annular shape of the double watertight bottom 20.

[0059] As shown in particular in Figures 7 and 12, the hull 10 has on the sides thereof a plurality of through openings 51, 52, 53, each of which is delimited:

[0060] - below, by a portion of said double watertight bottom 20,

[0061] - above, by a portion of said covered upper deck 40, and

[0062] - laterally, by two contiguous columnar watertight compartments 31, 32 or 32, 33 or 33, 31.

[0063] As shown in particular in Figure 8a, the waterline WL of the floater 1 passes through said through openings 51, 52, 53. Therefore, such openings put the moon pool 2 delimited by the floater 1 in communication with the open sea .

[0064] As it will be resumed below, the aforesaid through openings 51, 52, 53 create discontinuities in the plating of the hull 1, with effects in terms of both transparency to the waves and distribution of the hydrostatic thrusts .

[0065] In particular, the aforesaid through openings 51 , 52 , 53 allow increasing the transparency of the floater to the thrust of the waves and therefore reducing the motions of the floater which, in particular, would be detrimental to the operating ef f iciency of the hori zontal-axis wind power generator 100 .

[0066] As shown in the accompanying Figures , the floater 1 can comprise one or more reinforcing structural elements 34 , 35 , 36 which are arranged at said through openings 51 , 52 , 53 and connect said covered main deck 40 to said double watertight bottom 20 . Such reinforcing structural elements 34 , 35 , 36 essentially have the function of contributing to the structural rigidity and lateral stability of the floater 1 .

[0067] Preferably, said one or more reinforcing structural elements 34 , 35 , 36 consist of watertight compartments which are structurally integrated with the covered main deck and the double watertight bottom and contribute to generating hydrostatic thrust .

[0068] Alternatively, according to embodiments not shown in the accompanying Figures , the aforesaid reinforcing structural elements can consist of tubular bodies which essentially perform only a structural support function without actually providing a signi ficant contribution in terms of hydrostatic thrust .

[0069] The floater 1 according to the invention is not ascribable to any of the types of semi-submersible floating platforms of the conventional type . In fact , the floater 1 has geometric, static and dynamic features which clearly distinguish it from floating platforms of the conventional type .

[0070] The floater 1 is evidently not comparable to the TLPs nor the SPAR-BUOYs ; furthermore , due to the features thereof of immersion and transparency to the waves , the floater 1 cannot be classi fied as a semi-submersible platform nor as a platform of the barge type .

[0071] A floating platform of the barge type B has a hydrostatic thrust uni formly distributed along the perimeter thereof , as diagrammatically shown in Figures 13 a-b . In fact , a floater of the barge type has full sides along the whole longitudinal and transversal extension, regardless of the plan shape (polygonal , circular, full , or toroidal ) . Such a configuration makes a barge platform very sensitive to the action of the incident sea, since the large floating area and the great shape stability make it follow the slope of the waves as they pass . Such a lack of transparency to the incident sea makes the Barge configuration an unsuitable choice for very open and energetic seas . [0072] The floater 1 according to the invention differs from the barge configuration due to the lack of uniformity in the hydrostatic thrust, since the sides of the floater, along the whole perimeter, do not provide for a uniform distribution of the volumes due to the discontinuity in the side plating, caused by the presence of the aforesaid through openings 51, 52, 53. Such through openings in the plating 51, 52, 53 cause the hydrostatic thrust volume to have a discontinuous distribution (as shown in Figure 15b) and to be concentrated in some well-defined areas corresponding to the columnar watertight compartments 31, 32, 33

(preferably arranged at the vertices of the floating figure) . If the floater 1 also comprises the aforesaid one or more reinforcing structural elements 34, 35, 36 (consisting of watertight compartments) , part of the hydrostatic thrust volume is also arranged in the middle of each side (in the middle of each through opening) . Such measures (openings on the sides and non-uniform distribution of the volumes) improve transparency to wave motion and therefore the dynamic behaviour and therefore the efficiency of the horizontal-axis wind power generator 100.

[0073] A floating platform of the semi-submersible type S aims to maximize transparency to wave motion. To achieve such a purpose , the whole hydrostatic volume is concentrated at the ends of the vertices of the typically polygonal plan of the platform itsel f , as diagrammatically shown in Figures 14 a-b . This result is obtained by means of very immersed end columns with a limited diameter connected by very slender arms with a typically circular section and an exclusively structural function . Such a configuration, which could seem to be optimal , is however inconvenient for both the construction, di f ferent from conventional shipbuilding carpentry, and the signi ficant immersion which makes the launch, set-up at quay and shallow-water implementation thereof di f ficult .

[0074] The floater 1 according to the invention di f fers greatly from the conventional semi-submersible configuration, in particular, due to the presence of the aforesaid double watertight bottom 20 , provided with non- negligible structure and volume , which distributes part of the hydrostatic thrust along the peripheral development of the floater . Furthermore , the contribution to the hydrostatic thrust given by the double bottom ( in addition to the contribution of the columnar watertight compartments 31 , 32 , 33 ) allows containing the immersion of the floater 1 within limited values to facilitate the assembly thereof in shipbuilding carpentry workshops and the set-up at quay, as well as the implementation even with limited depths .

[0075] A further di f ference between the floater 1 in accordance with the invention and a conventional platform of the semi-submersible type lies in the presence of the aforesaid at least one covered main deck 40 , which ( as it will be resumed hereinafter ) can internal ly define a corridor 44 to allow the safe transit of personnel from one columnar watertight compartment to another one , as well as it can define closed and accessible rooms suitable for accommodating plant engineering, in particular electricity conversion and storage plant engineering .

[0076] A comparison between the floater 1 in accordance with the invention and the conventional spar-buoy platforms is not even considered, due to the lack of an extended-plan figure in the case of the spar-buoy platform .

[0077] As shown in particular in Figures 7 and 8 , the hori zontal-axis of fshore wind power generator 100 is supported by a tower 101 which rises from said floater 1 at one of the aforesaid columnar watertight compartments . In the following description, the columnar watertight compartment 31 at which the support tower 101 of the hori zontal-axis wind power generator 100 rises is referred to as the "main columnar watertight compartment

31" .

[0078] In accordance with the invention, the displacement volume of the main columnar watertight compartment 31 is greater than the displacement volume of each of the remaining columnar watertight compartments 32 , 33 , hereinafter referred to as " secondary columnar watertight compartments" .

[0079] In general , "displacement volume" means the volume of a body immersed in a fluid which determines the movement ( displacement ) of an equivalent volume of fluid; the volume of fluid displaced in turn causes a vertical upward thrust on the immersed body equal to the weight thereof . Therefore , the displacement volume of a watertight compartment corresponds to the immersed volume of such a compartment ; the immersed volume will be a function of the vertical balance between the weight weighing on the watertight compartment and the thrust generated by the weight of the displaced fluid volume . The extent of the displacement volume of a watertight compartment is definable a pri ori (within certain intervals ) in the context of the design of the floater in which such a watertight compartment i s inserted .

[0080] During the step of si zing the floater 1 , the ratio between the displacement volume of the main columnar watertight compartment 31 and the displacement volume of each of the remaining columnar watertight compartments 32 , 33 is chosen so that the centre of the hydrostatic vertical thrusts generated by the floater 1 is positioned as close as possible to the main columnar watertight compartment 31 .

[0081] Such a precaution determines an asymmetrical distribution of the main dimensions and of the displacement volumes in the floater 1 . This first allows reducing the si ze and therefore the total weight of the hull structure, to the advantage of construction costs . Secondly, the aforesaid asymmetrical distribution also allows reducing the ballast to be placed in the secondary watertight columnar compartments 32 and 33 , necessary to compensate for the weight of the assembly consisting of the tower 101 and the hori zontal-axis wind power generator 100 , positioned at the main watertight columnar compartment 31 , and thus maintain a straight set-up of the floater 1 .

[0082] By virtue of the aforesaid asymmetrical distribution of the displacement volumes , according to which the displacement volume of the main columnar watertight compartment 31 is much greater than the displacement volume of the individual secondary columnar watertight compartments 32 and 33 , it is possible to move the centre of the hydrostatic vertical thrusts towards the main watertight columnar compartment 31 . With respect to such a centre of thrusts , the arm must be calculated with respect to the centre of the weights of the structure , of the on-board systems and of the ballast water necessary to compensate for any imbalances between the reciprocal positions of the two centres .

[0083] From an operational point of view, a straight floating set-up is reached when the distance between the centre of the hydrostatic thrusts and the centre of the weights is zero and the two centres are aligned vertically . This result is obtained with an appropriate dosage of ballast water which has greater ef fectiveness the greater the arm thereof is with respect to the centre of the hydrostatic thrusts .

[0084] Being able to use a smaller amount of ballast water to compensate for the distribution of the weights onboard the floater 1 also allows limiting the total displacement of the unit and therefore the immersion thereof ; this is an extremely important and useful factor during the set-up steps at the quay o f the shipyard .

[0085] The asymmetrical distribution of the displacement volumes therefore synergistically cooperates with the other features of the floater 1 in accordance with the invention, relating to the positioning of the displacement volumes in the floater 1 ( displacement volume concentrated in the columnar watertight compartments and in the double watertight bottom) , in simultaneously reducing the quantity of ballast necessary to balance the non-symmetrical distribution of the weights more concentrated at the main columnar compartment , and, as a final result , also in reducing the immersion of the floater due to the reduced overall weight of the assembly compared to a floater of the same si ze in plan and with a uni form distribution of the displacing volumes .

[0086] The combination of the features of the floater 1 in accordance with the invention causes the floater 1 for the support of an of fshore wind power generator to have limited immersions typical of conventional floaters of the barge type , such as to allow both the complete set-up at the shipyard and the use of the vessel even in sites with depths starting from 50m, while being less subj ect to motions induced by weather-marine conditions as compared to conventional floaters of the barge type .

[0087] Preferably, the floater 1 in accordance with the invention has an immersion from 8 to 12 m, and even more preferably from 8 to 10 m . In the accompanying Figures , the waterline of the floater 1 is indicated by WL .

[0088] Preferably, the displacement volume of the double watertight bottom 20 is equal to 40- 60% of the displacement volume of the watertight columnar compartments 31 , 32 , 33 .

[0089] Preferably, the displacement volume of the watertight columnar compartments 31 , 32 , 33 forms 50-70% of the total displacement volume , while the displacement volume of the double watertight bottom 20 forms 20-40% of the total displacement volume .

[0090] The same definition previously given to "displacement volume of a watertight compartment" also applies to the expression "displacement volume of the double bottom" , as wel l as to " total displacement volume" .

[0091] Advantageously, the floater 1 can comprise a plurality of damping flaps 24 which are associated with said hull 10 and have the function of damping the motions of the floater 1 . Preferably, said damping flaps 24 are associated with said double watertight bottom 20 . Preferably, said damping flaps 24 are arranged in the empty space internally delimited by the closed annular shape of said hull 10 .

[0092] Preferably, the hull 10 has a closed annular triangular shape in plan, wherein there are three columnar watertight compartments 31 , 32 , 33 , each of which arranged in one of the vertices of the closed annular triangular shape .

[0093] Advantageously, for reasons of symmetry, the aforesaid closed annular triangular shape is equilateral or isosceles .

[0094] In accordance with a preferred embodiment of the invention shown in the accompanying Figures , the hull 10 has a closed annular isosceles triangular shape in plan, wherein the main columnar watertight compartment 31 is arranged at the vertex opposite the base of the closed annular isosceles triangular shape . Such a pre ferred configuration allows positioning the main watertight columnar compartment 31 on the plane of symmetry of the floater 1 , to the advantage of the stability of the floater 1 itsel f .

[0095] Preferably, as shown in particular in Figures 10 and 11 , each of said columnar watertight compartments 31 , 32 , 33 has , in plan, a substantially triangular shape , net of small deviations from the triangular shape at the vertices dictated by construction needs .

[0096] Preferably, in the case of a floater with a closed annular isosceles or equilateral triangular shape , the ratio between the displacement volume of the main columnar watertight compartment 31 and the displacement volume of each of the remaining two columnar watertight compartments 32 , 33 is comprised between 1 . 9 and 2 . 1 , and preferably equal to 2 .

[0097] In the preferred case in which the floater 1 has a closed annular isosceles or equilateral triangular shape , the asymmetrical distribution of the displacement volumes in cooperation with the other features of the floater 1 in accordance with the invention ( displacement volume concentrated in the columnar watertight compartments and in the double watertight bottom) is particularly ef fective in reducing the immersion of the floater 1 itsel f .

[0098] More in detail , from a geometric point of view, the centre of gravity of a triangle is located at the intersecting point of the three medians thereo f ; in the particular case of the isosceles or equilateral triangle , the centre of gravity is located at 1 / 3 of the height thereof . In the special case of a uni form and homogeneous weight distribution on board, this would also be the point of application of the weight forces . This does not occur in the floater 1 in accordance with the invention, since the hori zontal-axis wind power generator 100 , together with the support tower 101 , unloads the weight thereof at one of the vertices of the closed annular triangular shape of the floater, i . e . , at the main watertight columnar compartment 31 . For this reason, the global weight distribution and therefore the centre of gravity are also shi fted towards the main watertight columnar compartment 31 .

[0099] To fully or partially compensate for the imbalance which would arise , the displacement volume of the main watertight columnar compartment has been increased with respect to the displacement volume of the other two watertight columnar compartments 32 and 33 .

[00100] Advantageously, for reasons of lateral stability, the two secondary watertight columnar compartments 32 and 33 have identical geometries .

[00101] As previously highlighted, by virtue of the asymmetrical distribution of the displacing volumes , it is possible to reduce the structural weight of the floater 1 in terms of amount of ballast necessary to compensate for the weight concentration of the systems weighing on the main watertight columnar compartment 31 . By virtue of this , it is therefore possible to reduce the immersion of the floater to the advantage of the completion on the production shipyard quay .

[00102] Advantageously, the hull 10 is provided with floodable watertight compartments 60 with a ballast function . Said floodable watertight compartments 60 are arranged in di f ferent portions of the hull 10 . To this end, the floater 1 is provided with a ballast system of said floodable watertight compartments 60 with sea water, not shown in the accompanying Figures .

[00103] Preferably, said floodable watertight compartments 60 are floodable in a di f ferentiated manner with respect to each other to allocate liquid ballast in di f ferent portions of the floater 1 as a function of the operating stability needs induced by variations in operating and/or weather-marine conditions .

[00104] Preferably, the aforesaid floodable watertight compartments 60 are obtained in the inner volume of said columnar watertight compartments 31 , 32 , 33 and/or in the inner volume of said double watertight bottom 20 .

[00105] In accordance with the preferred embodiment shown in the accompanying Figures , and in particular in Figure 11 , the aforesaid floodable watertight compartments 60 are obtained in the inner volume of the main columnar watertight compartment 31 and of said secondary columnar watertight compartments 32 , 33 and at least in the inner volume of the portion 21 of said double watertight bottom 20 which connects the two secondary columnar watertight compartments 32 , 33 . In the inner volume of the portions 22 and 23 of said double watertight bottom 20 , which connect each of the two secondary columnar watertight compartments to the main watertight columnar compartment 31 , non- f loodable watertight compartments 61 can be provided . [00106] Advantageously, the aforesaid covered main deck 40 internally defines a corridor 44 to allow the transit of personnel from one columnar watertight compartment 31 , 32 , 33 to the other . Operatively, by virtue of the aforesaid covered main deck 40 , it is possible for onboard personnel to access all the areas of the floater 1 , thus operating safely . This allows carrying out the necessary maintenance operations of the floater 1 during the operational li fe thereof in a simple and inexpensive manner .

[00107] Preferably, as shown in the accompanying Figures , and in particular in Figure 10 , the portion 41 of said covered main deck 40 which connects the two secondary columnar watertight compartments 32 , 33 has a cross-section in plan ( traced according to a crosssection plane orthogonal to the longitudinal axis of the deck portion) equivalent to that of each of the two portions 42 , 43 of the covered main deck 40 which connect the two secondary columnar watertight compartments 32 , 33 to the main columnar watertight compartment 31 .

[00108] Advantageously, the portion 41 of said covered main deck 40 which connects the two secondary columnar watertight compartments 32 , 33 can have a cross-section in plan greater than that of each of the two portions 42 ,

43 of the covered main deck 40 which connect the two secondary columnar watertight compartments 32 , 33 to the main columnar watertight compartment 31 so as to have more useful space on board to be used as a technical room .

[00109] Preferably, the portion 41 of said covered main deck 40 which connects the two secondary columnar watertight compartments 32 , 33 is intended to function partly as a corridor and partly as a technical room .

[00110] Advantageously, the inner volume of each of said one or more columnar watertight compartments 31 , 32 , 33 can be partly occupied by technical rooms .

[00111] In accordance with the embodiment shown in the accompanying Figures , and in particular in Figures 8 and 9 , the floater 1 can comprise an open secondary deck 70 which is arranged above said covered main deck 40 and covers the empty space internally delimited by the closed annular shape of said hull 10 .

[00112] The hull 10 comprises plating walls 11 , internally supported by a load-bearing framework (not shown in the accompanying Figures ) . Preferably, such plating walls consist of flat panels mutually connected to one another . Such a constructional solution can be more easily adopted when the hull has a closed annular shape of the polygonal type , which is defined by the intersection of flat surfaces . [00113] The possibility of creating the plating of the hull 10 by using flat panels makes the floater 1 simple and cheap to build with the typical methods of the large shipbuilding industry . In this entirely preferred case , the floater 1 for the support of an of fshore wind power generator according to the invention has construction costs comparable to those of conventional floaters of the barge type .

[00114] Preferably, the aforesaid flat panels are connected to one another by welding .

[00115] Advantageously, the aforesaid flat panels can be prefabricated panels .

[00116] Advantageously, by virtue of the intrinsic stability thereof , the floater 1 according to the invention can be provided with simple moorings to the underwater bottom, indicated with numeral 80 in Figure 7 . This makes the floater 1 simply and quickly moorable onsite . All this contributes to making the process preceding the production of energy by the floating unit cost-ef fective ( i . e . , the so-called CAPEX ) .

[00117] Advantageously, the floater 1 in accordance with the invention can be used as a platform for positioning not only the hori zontal-axis wind power generator 100 , but also other apparatuses for generating electricity from renewable sources , so as to increase the speci fic production and compensate for the lack of continuity of natural resources . Thereby, it is possible to make the economic investment , which is summari zed in the LCOE ( Leveli zed Cost Of Energy) parameter, more ef ficient and competitive .

[00118] Advantageously, the floater 1 can comprise one or more vertical-axis wind turbines 81 supported by said covered upper deck 40 , as shown in Figures 7 and 8 , for example .

[00119] Advantageously, the floater 1 can comprise one or more Wave Energy Converters 82 mechanically connected to said hull 10 , as shown in Figures 7 and 8 , for example .

[00120] Advantageously, the floater 1 can comprise a plurality of photovoltaic solar panels 83 , installed on the portions of said floater 1 intended to remain emerged in operating conditions .

[00121] Preferably, said photovoltaic solar panels 83 are installed on said open secondary deck 70 .

[00122] Advantageously, i f the aforesaid open secondary deck 70 is used only for the installation of the photovoltaic solar panels 83 , said open secondary deck 70 can consist of a lattice support structure , i . e . , of a structure suf ficiently light to support the photovoltaic solar panels without unnecessarily weighing down the floater 1 . Furthermore , the lattice support structure does not define a continuous surface , but , on the contrary, it has several openings which allow the passage of air flows useful for cooling the photovoltaic solar panels and thus improve the performance thereof .

[00123] Advantageously, the floater 1 can comprise one or more electrolysers 91 which are suitable for extracting hydrogen from desalinated sea water and are installed in technical rooms internally obtained from the hull 10 and/or the covered main deck 40 . Advantageously, the floater 1 can be provided with a desalination system 95 for producing desalinated water to be fed to the aforesaid electrolysers 91 .

[00124] In accordance with the embodiment shown in the accompanying Figures and in particular in Figure 10 , said one or more electrolysers 91 are arranged in the inner volume of the portion 41 of the covered main deck 40 which connects the two secondary columnar watertight compartments 32 , 33 .

[00125] Advantageously, in technical rooms obtained inside the hull 10 and/or the covered main deck 40 , the floater 1 can comprise :

[00126] - one or more storage tanks 92 of liquid or gaseous hydrogen produced by said one or more electrolysers 91 ; [00127] one or more fuel cells 93 which can be supplied with the hydrogen produced by said electrolysers 91 and are suitable for converting hydrogen into electricity; and possibly

[00128] - one or more batteries 94 for the accumulation of the electricity produced on board .

[00129] Preferably, said one or more hydrogen storage tanks 92 and said one or more Fuel Cells 93 are located in technical rooms obtained in the watertight columnar compartments 31 , 32 , 33 , together with said one or more batteries for the accumulation of energy 94 .

[00130] Advantageously, the oxygen coming from the electrolysis process can be sent to an aquaculture plant located in the moon pool delimited by the floater 1 , or externally in the vicinity thereof .

[00131] The invention provides several advantages , some of which have already been described .

[00132] The floater 1 for the support of an of fshore wind power generator in accordance with the invention has limited immersions , typical of conventional floaters of the barge type , such as to allow both the complete set-up at the shipyard and the use of the vessel even in sites with depths starting from 50m, while being less subj ect to motions induced by weather-marine conditions with respect to conventional floaters of the barge type . [00133] The floater 1 in accordance with the invention has a configuration which is a hybrid between the geometry of a conventional semi-submersible floater and the geometry of a conventional floater of the barge type , combining the advantages of the transparency to wave motion of the semi-submersible one with the advantages of the product industriali zation of the barge one .

[00134] Furthermore , the presence of large inner spaces inside the floater 1 , essentially linked to the presence of the covered main deck, allows the installation of integrated auxiliary systems for trans forming and storing energy for the benefit of the continuity of electricity distribution .

[00135] The floater for the support of an of fshore wind power generator has construction costs comparable to those of conventional floaters of the barge type and is therefore simple and cheap to build with the typical methods of the large shipbuilding industry .

[00136] By virtue of the presence of the covered main deck, the floater 1 allows carrying out the necessary maintenance operations of the unit during the operational li fe thereof in a simple and inexpens ive manner .

[00137] The floater 1 for the support of a hori zontalaxis wind power generator in accordance with the invention allows , in particular, the following advantages to be achieved :

[00138] it has small immersions , such as to allow both the complete set-up at the shipyard and the use of the floater even in sites with depths starting from 50m ( thus expanding the number of installation sites ) ;

[00139] it has a simple and therefore cost-ef fective construction, in line with the typical methods of the large shipbuilding industry;

[00140] it is creatable by means of industriali zed construction and logistic methods that allow responding to the immediate demands of the market for having large numbers of large-si zed floaters within a very limited time span;

[00141] it has ( even in the complete configuration) a high stability during the step of towing it to the anchoring site

[00142] it has a simple and quick on-site mooring, to make the entire process preceding the production of energy by the floater cost-ef fective , i . e . , the so-called CAPEX, and

[00143] allows reducing and simpli fying costs and maintenance operations of the floater during the operational li fe , i . e . , the so-called OPEX .

[00144] The availability of large protected spaces inside the floater 1 allows the installation on the platform itself of multiple apparatuses for producing and storing energy from renewable sources, in addition to a horizontal-axis wind power generator. Compared to a "disaggregated" solution, i.e., a solution where each single system uses a dedicated floater, the floater 1 according to the invention saves the costs deriving from mooring and the related operations relating to the single floaters, using a single platform.

[00145] Therefore, the invention thus devised achieves the pre-set purposes.

[00146] Obviously, in the practical embodiment thereof, it may also take shapes and configurations different from that disclosed above, without departing from the present scope of protection. [00147] Furthermore, all details may be replaced by technically equivalent elements, and any size, shape, and material may be used according to needs.