WO2009093988A2

WO2009093988A2 - Energy generating system from sea waves

Info

Publication number: WO2009093988A2
Application number: PCT/TR2009/000007
Authority: WO
Inventors: Mehmet Terziakin
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-23
Filing date: 2009-01-22
Publication date: 2009-07-30
Anticipated expiration: 2010-07-23
Also published as: TR200800454A2; WO2009093988A3

Abstract

The invention is an electricity generation method that converting the actions of the buoys which are connected under a platform, with the waves to a water pumping action with cylinder-piston couples, turning the Pelton turbine with this water and obtaining electricity from a generator which is coupled with this turbine.

Description

ENERGY GENERATING SYSTEM FROM SEA WAVES

This invention relates to the technology of energy generating systems from sea waves. Especially, this invention is about pumping water with the movement of buoys articulated to offshore platforms, and converting to electrical energy with the groups of Pelton turbines and generators and transportation this energy to shore.

For a long time, it is known that there is a large potential of energy in the sea waves. Especially, in the oceans, there is an important potential of energy like 7OkW per meter of a wave crest length. Opposite the renewable energy sources like wind energy, waves are energy sources can last through a year continuously. Particularly, it presents us the potential of obtaining energy continuously from oceans. Although there are plenty of patents and designs to generate energy from waves since 19^th century, still no commonly used and efficient technology exists. Existing methods are classified in some main categories.

Some of these methods are systems having the principle of obtaining compressed air in a closed tank and converting this into energy. In these systems, energy is acquired by the compressed air driving a gas turbine. But, with this method the gained pressure of the air is fairly low and it does not have enough energy. Some kinds of these systems' principle are converting the up and down actions of the buoys connected to sea bottom to mechanical or electrical energy. And some of the systems are the machines that change the energy of the waves hitting to jointed plates into mechanical energy. And another group of system operates with the turning movement obtained from the converted movements of the buoys. Generally, these are the systems which convert very low ratio of the energy of the waves into mechanical and electrical energy; also have problems in operating, and not economical.

Some of these systems have some motional components under water. Having these motional parts under water can lead into serious problems, it is hard to maintain and it is an expensive method in the conditions of the oceans having intense waves. Although there are many patents up to this time and many prototypes were tested in sea conditions, most of these systems were incapable of producing energy economically. For instance, one of the relatively successful examples, Stephen Hugh Salter in US patent 3,928,967, was experienced in ocean conditions. The system called Salter's Duck was observed that it uses very few part of the wave energy productively, and in case of the big waves, it was seen that it could only take a little part of the energy of waves. It was mostly because of the short distance with rising parts' of the buoys, moving up and down with the wave, and it's joint. That is to say, it is because of the buoy stroke's being a little percent of the height of the buoy under water. Here, a little part of the total buoy volume can be used. On the other hand, a complicated system was used to obtain pressure against this floating movement. Supplying pressure to hydraulic oil with the movements of the buoys', and obtaining mechanical energy in a hydraulic engine with this pressure is a method that has high setup cost and low efficiency.

On some of the systems still tested, there are systems supplying rotational movement in the hydraulic motors which driven by pressured oil obtained from the changing of the angles between the long and relatively thin cylindrical buoys, connected to each other like series and these systems are still being tested. If such a system takes the wave along its axis, there won't be a relative motion, because the cylindrical buoys will rise all together. So there won't be any energy production. Else if, the wave comes straight to the axis of the cylinders, for example, one meter diameter cylinders will move up and down so just a part of one meter of the wave can be used.

An efficient wave energy exploitation system should include these characteristics:

- It must convert wave energy into mechanical and electrical energy efficiently.

- According to the conditions of the nature, waves can come to the shore from different directions and in different height and frequency. It must be compatible in variable characteristics of height, frequency, direction, etc. and it should keep its operation efficiency high during variable characteristics.

- Active mechanisms should be easily reachable place, maintenance and repairing should be easily done, and they should be over waterline.

- It should have the resistance of sinking or having an accident in storm conditions. - It should have low setup cost, operating and maintenance costs should be in reasonable level. And service life should be long.

- It should be used where sea bottom is in deep and it should include solutions about transporting the electricity to the shore. - It should be mobile over the sea, it can be taken away from dangers such as storms, drill ices due to the season and natural conditions.

In the system which is the theme of the invention, there are buoys which are connected to an offshore platform and located to take the wave action from front. These buoys are moving up and down with the waves. Groups of piston cylinders, one side connected to buoys or arms of the buoys, the other side connected to the platform which buoys are connected, are supplying pressured water with this up and down action. This pressured water turns a Pelton turbine and turbine shaft drives a generator. The electricity taken from one or more generators is transferred to shore by a conductor passing through the sea. Preferably, horizontal projections of these buoys should be thin, long rectangles and long edge of the rectangle must be parallel to the wave crest. Buoys should turn around to take wave action from their long edges. In other words, with the crest of the wave a buoy should rise as much as possible. Front and backsides of the buoys should be rounded for decreasing impact resistance of the waves. In real wave profiles, when looked through the profile, it can be easily seen that wave's back-crest part have a section thought as narrow and sharp. For example, in the case that the horizontal projection of the buoy is a 5x5m square, height of the wave cannot be used productively and the oscillation of the buoy will be limited. The buoy will only float on the average height of the water and make small oscillations. But the purpose must be using the top and bottom levels existing over water as much as possible. For instance, a thin and long rectangle shaped buoy, taking the wave action through its long side, will rise and descend with the wave. Thus the up and down stroke will be much higher. In another example, when the horizontal projection of the bouy is a 0.5x5m rectangle, and the long side is located parallel to the wave crest, buoy will rise and descend with the top of the wave. So building the buoys long and thin will increase usable stroke length/displacement volume.

The platforms, on which the buoys are connected, will preferably be anchored to sea bed. By means of a system, the direction of the wave will be determined simultaneously, and the direction of the platform will be changed to make its length parallel to wave crest. This work will be done by easing away and tightening the ropes, connected to sea bed, with capstans. There will be many of these platforms side by side and the electricity produced will be collected and transported to shore or will be used in an offshore manufacturing, using much electricity.

Five figures were prepared to explain the invention.

• In Figure 1, main piston-buoy combination in which energy would be extracted from wave motion and providing pressured water which will be used hi pelton turbines is shown.

• In Figures 2 and 3, cylinder of the buoy is shown in suction and pumping cycles. At the pumping stage while wave is raising the buoy submerged volume becomes larger, and during descending of the buoys at the suction cycle decrease in submerged volume is shown. • In Figure 4, these systems making one of the rows over the platform by arranging one after the other and the Pelton turbine over them is shown.

• In Figure 5, the entire platform about its general structure is shown.

In the setup seen in Fig.l, a buoy (1) which Length(L)/Width(W) ratio is larger than one, is connected to a horizontal arm (2) with a joint (3). With the buoy (1), the arm (2) is moving up and down. There is the joint (5) that the arm (2) is connected to the part (7) located under the platform which is not seen in the figure. This joint (6) is connected to the end of a piston (4), and while moving up and down with the wave it makes the piston (4) to move upwards and downwards in the cylinder too. This cylinder (8) was built as a hose pump and during every up and down action it sucks water from sea or internal pipe system and pumps it into pressured water line. The upper end of the cylinder is jointed to the platform and its lower end is hinged to the arm holding the buoy. Instead of water, another fluid can be used too, for example, oil or fresh water. In this case there must be a closed system in which the oil is circulated in a closed loop.

There are some conditions to operate the system effectively. One of them is buoy's taking the wave action from front, buoy's being narrow and buoy's long side's being parallel to wave crest. Because wave energy is a fact that over the sea surface there becoming series as peaks and bottoms and this actions moving perpendicular to the line of wave crest. Also, the length of the buoys which will take the wave action should be parallel to the line of wave crest line, and taking the wave along the long side of the buoy will make the buoy rise and descend better. Moreover, buoys having a short draft or its having a bit flat shape, so it's won't being a resistance to the wave will be suitable.

In Fig.l, M is the mass of the buoy, Ld is the distance between the joints 3 and 5, Lp is the distance between the joints 5 and 6, and A is the area of the buoy's horizontal projection. Here, the inertia resulting from the change of the direction upwards and downwards and the weight of the arm, number 2, is ignored. The lifting force acting on the buoy while rising, should meet the weight of the buoy (M), also is should meet the force(Fd), the force acted on the joint 3, caused by the force (Fp), which would lift the piston up, Fd = Fp * (Lp / Ld) and lifting force (K) is the sum of these two forces. K=M+Fd

The incoming wave will raise the buoy number 1, and this lifting force (K), will create an upwards directional force (Fd) over the joint number 3. This joint will make the arm (2) rise. The arm (2) is a part connected to the fixed platform from one side, connected to the piston from middle, and connected to the buoy from its end. The force acting on the joint number 3 upwards, will act on the piston as Fp=Fd(Ld/Lp).

During buoy's descending with the wave, the pressure inside the cylinder will create a force (Fp) upwards over the joint number 6, and this force will act on the buoy upwards as a force Fp= Fd*(Ld/Lp). Because of the weight of the buoy is bigger than this upwards directional Fd force, the buoy will descend with the wave. At this time the piston will work as a suction pump, lower side becoming larger, sea water will be vacuumed, and upper side of piston becoming narrower, water will be compressesd and transported to the pressured line. With this line the water pumped by the pistons will be collected and transported to the Pelton turbine over the platform. Francis types of turbines can also be used in the system too.

If, pistons' giving energy is wanted during both rising and descending strokes, buoy's draught will change in descending and rising strokes. In other words, during rising stroke, buoyancy of water (K) should be enough to meet both buoy's own weight (M), and the force (Fd) acting on the joint, which buoy is connected, upwards. So, K=M+Fd. And during descending stroke, the buoyancy of water to the buoy will be K=W-Fd. And this, the difference 2Fd, occurred during the change of direction, will be met with the buoy's sinking into water more or less. Here, the area's, affected by the pressure during the pistons' pushing and pulling action, being different is also ignored.

In the areas where the potential of wave energy is high, generally where the wave height is about 2.5m and sometimes increasing to 6-7m high, buoy's routine operating conditions for example, as 3 -4m up and down stroke it is needed to build the system as it can produce energy. Also in severe sea conditions, it should be a durable system. It will be effective to use springs, rubber mountings to absorb the impact force at the up and down limits of buoy stroke between the platform and buoy arm(2), or at the joints (5,6).

In nature it is inevitable to be exposed to harsh waves. Here, buoy's having a perfect waterproof structure and the joints number (3) and (5) handling the force acting on the buoy is very important.

A similar one of the system shown in the figure can also be used to obtain energy from the waves coming to coast. In this case, the piston-cylinder couples are connected to a base on the coast as horizontal or with an angle. One side, for example the cylinder is fixed to the base on the coast. And the other hand is connected to a vertical plate or a buoy which the waves are able to hit. Plate or buoy will be pushed by the wave because of the hitting and repositioning the buoy or the plate is done by an apparatus like a spring or something similar.

In Figure 2 and 3 buoy's sinking difference in the case piston's being used as a suction pump with two directional pumping. In Figure 2, buoy (1) is sinking more, because in the period of rising buoyancy of water supplies the force to push the buoy and piston upwards. And in Figure 3, piston is pulled down because of the weight of the buoy (1), so the draught of the buoy is less. During design process, weight of the buoy should be enough to pull the piston downwards. If total wave height is called as H wave, the total stroe of the buoy because of the wave will be Hstroke = Hwave - Hbuoy. To increase buoy stroke, it is needed to make the horizontal projection area (A) higher, and H-buoy, buoy distance shorter. The horizontal projection area of the buoy's being large and buoy structure's being able to take the wave affect all along will be suitable.

In other words, when the buoy pumps water as a suction pump, when the cylinder is lifted by the water, the buoyancy of water is equal to the sum of the weight of the buoy and the vertical force caused by the cylinder. For example, the buoy having a vertical projection area, 2x1 Om, a rectangle, if its weight is 6000kg and to lift up the piston 6000kg of force will act on the joint 3, it will be lift upwards by 12000kg of force. Because of having a horizontal projection area, 20 m², a part of 0.6m height will sink into water. The buoy can also make the cylinder pump water with the same pressure value as a suction pump while descending if it pulls the piston downwards with a force of 6000kg. In this case water will , be at the bottom level of the buoy. In short there will be 60cm of difference at the draught of the buoy while changing its direction from downwards to upwards. For example, if the wave height is 2.5 m, the effective up and down stroke of the buoy will be 1.9 m. So, because a unit like this cannot take the energy of the wave in one try, the energy of the wave could be taken step by step with a consecutive order of these units. If, the buoyancy of water is wanted to be high during designing, there will be a decrease in the effective stroke. If system, a free descending buoy and only pumping while rising, is preferred, it is possible to make the drought of the buoy, buoyancy of water and effective stroke higher. So, in this case the piston will work in one direction.

In these calculations above, the details coming from the geometry of the system, friction force, etc. was ignored and for expressing the concept the calculation was simplified. If the height of the wave between 2-4m and 10 sec of period is accepted for the oceans having high energy potential of wave energy, it can easily seen that a large amount of energy can be supplied in this way. In this experiment, if the period of the wave is accepted as 10 sec, the raw energy potential, supplied by the buoy during one period, is doing a work as 2*1.9m*6000kg=22800kgm because of rising and descending action. And, power supplied by a buoy is 22800kgm/10sec=2280kgm/s = 22.35kW = 30.4 HP. With this type of a system, some part of the energy potential can be used with a buoy. Because of this, a productive system can be setup by locating some of these units consecutively and collecting the water pumped from these units to drive a Pelton turbine.

But, if the buoy's (1) one directional action will be used, in this case only under and over of the piston(8) there will be pressure and the force acting on the buoy won't change during rising and descending action. So, buoy will use the wave height as it is, useful stroke will get larger, but it will be used in one direction. In the inland seas, where the heights of the waves are low, and cylinder's one directional compression and during rising and descending not having a difference between buoy draughts will be more suitable. Then, buoy can be designed as it can sink more and supply buoyancy more. In the example above, if we imagine that the buoy was built lighter and had a draught 1.25m, and its own weight as 5000kg, and the force acting on the piston as 20000kg, the buoyancy of water can be calculated as 25000kg. The work of the 20000kg force acting on the piston, will be 50000kgm along 2.5 m height. In 10 seconds of period, the power will be 5.000 kgm/s = 49 KW = 66.66 HP.

Filtering the intake sea water first, will prevent non return valves and the other parts being ^• closed. Accumulations are inevitable in these filters occasionally. Because of this, a flow from inside to outside will be applied from time to time to extract the unwanted materials , on the filter.

An order of these units is shown in the Figure 4. Here, the units are like a row located consecutively. The upper parts (7), which buoy group is mounted, are connected under the platform construction. Here, the structure shown is an example of this design, also with other constructions; naturally the purposes told in this invention can be reached. For example, couples of pistons can be located in a parallel order and the buoy can be connected to the pistons directly. So, buoys' uncontrolled turning can be prevented. Another choice is connecting the piston-cylinder couples under the platform directly. For example, connecting the upper ends of the cylinders directly under the platform and the other ends to the buoys. In this case while the buoys' rising and descending, water will be pumped to the turbine. But, the system shown in the figure has strength and better structural properties to nature conditions. Cylinder-piston couples (4,8) of all units are pumping water to the pressured pipe line which is not shown in the figure. This pressured water is pumped to a Pelton turbine (11) or Francis turbine located on the platform. And a generator driven by this turbine will generate electricity. An automatic control system is adjusting the sectional area of the nozzle as enlarging or constricting, at the beam of water given to the turbine. And the generator, which cannot be seen in this figure, is transporting energy to the shore with power lines.

In Figure 5, a long energy generating platform on which there are many lines of consecutively ordered 5 buoy-piston units shown in Figure 4. The whole platform is connected to sea bottom with suitable connectors(lό). Steel rope is preferred to be used in application. Platform's position will be set to be parallel to the wave peak line and perpendicular to wave direction by easing away and tightening these connections with the mechanisms over the platform. Especially in deep waters, the weight of the rope is an excessive load, and it will cause an over-tension in upper parts. So, to carry the rope with buoyancy of water to prevent the risk of rupture, buoys having a material incompressible, lower density than water, will be useful if they are connected to the rope in certain distances. For example, when a rope, thousands of meters, which has this type of buoys at every 50 meters is connected to deep sea bottom, the over tension at the part near the connection to the platform will be prevented. Filling petroleum products such as oil, paraffin, benzene, etc. will be suitable to make the buoy lighter than water.

This buoy method for the ropes of the platforms over deep seas can also be used in different applications, for example, for the ropes of offshore petrol platforms.

The tensions in the ropes are controlled with sensors and for over stress conditions, tension is decreased by loosening it, or tightening the other ropes. Seas having high potential about waves and shallow waters are the ideal places for such a system. For example, north of England, west shores of North America, open seas at south of South America and off shores. These platform groups can be easily and economically used where the depth is over 1000m, the capacity of waves are higher in open seas. As it can be seen in the figure, weights, such as water tanks, have been put away from the axis of the platforms. The purpose is making the platform's body above(15) stable over the waves as much as possible. For example, an upwards and downwards rotational motion which occurred on the platform has to make these weights move more because of the geometry of the platform. Because of the inertia of these weights, they cannot make big movements. So, they will make the platform keep steadier or slow down the rotational motion. Both the ropes' (16) and the balance tanks' (15) being far away from the platform axis, being over the beams (14) is important for platform balance.

Due to the calculations and design, pontoons can also be used to make platform float in these regions. And an important point is, for not to spoiling the balance of the platform, these carrier pontoons should be under waterline of the platform.

The weights, located away from the platform axis (15), and/or the plates, which are not shown on the figure, and horizontally located in the water, will prevent the platform to move vertically with the wave action. For example, in the case of these weights' and/or the horizontal plates' in the water, being 6m away from the axis, will require 10 cm of rising or descending. And in the case of being 30 m away from the axis, it will require 60 cm of moving. It will be difficult to make 100 tons of weight this kind of periodic movement, so the platform will be significantly stable. These weights should be over water level and won't be affected by the waves. Therefore, it is the wave action's causing a resonance. In the other hand, an effective precaution for keeping the platform steady as much as possible is locating horizontal plates under water surface far away from the platform axis. During the platform's up and down movement, this plate will want to move by pushing the water with its both sides but it will face with an important resistance. For example, in the case of arm number 10's being 30 m long and, having a horizontal plate of 200 m² under water surface, it is very difficult to move with the wave up and down. This will have a damping effect as a shock absorber.

Here, an important subject is having the ability to change the direction of the platform due to the direction of the wave. During the changes of wave direction, the system, which changes the direction of the platform, is very important to operate productively. To do this, tightening or loosening method is applied to the steel ropes, which connected to sea bottom. An electronic control system determines the direction of the wave and/or direction of the wind. The capstans pull the ropes on the side wanted to be closer, and loosen the ropes on the side wanted to get away so, it supplies a change in direction.

And another simple method is to connect the platform to sea bottom with steel ropes to take the wave action from front every time. For example, the platform will be connected with the rope/ropes, which are parallel or which has narrow angles between them, in the wave direction (13) as seen in the figure. The ropes' only seen on the left of the figure, being connected to sea bottom closer to each other or to same point is an example to this simple method. As the waves and the wind changes direction, they want to drag the platform. The direction of the ropes must be parallel to the direction of the wave and wind, because they will be tightened and prevent the drag of the platform. Because of the ropes' having same length and being connected to two sides, platform will always change direction to take the wave action from its long side with the winds.

In application many platforms will be located side by side, and probably they will be used to carry conductors. So the distances between the platforms are important also. Using ropes also between the platforms will be useful to set the directions to each other.

The own weight of the rope can exceed its own rupture limit in deep seas. For example, in the case of a steel rope's, 1 cm² cross sectional area, being 4000m long, its volume will be 0.4m . So, density of 7.8 tons/m , and 1 ton/m water density and 1 ton/m bouyancy of water are considered, 6.8 ton/m³ * 0.4 m³ = 2,72 tons or 2720 kg of weight. If average strength of the steel is considered as 16000 kg/cm², and safety factor as 4, the limit load of the rope will be 4000kg. Because of this, using ropes which has low density will be useful. For example, in the case of using aluminium, density of 2.7 ton/m³, its part of 1 ton/m³ will be lifted by the buoyancy of water. So, the tension will be reduced. And another effective method is connecting buoys having a material incompressible, lower density than water, will be useful if they are connected to the rope in certain distances. For example a buoy, 1 m³ volume, contains benzene or kerosene density of 0.65 ton/m³, and if the weight of the buoy is ignored, it will supply 0.35 tons of buoyancy. Preventing to make the ropes stressed with their own weight by hanging these kinds of buoys on the rope. Buoy-platform connection can be articulated or sliding upwards and downwards. Closed, changeable voluminous vessels or preferably hydraulic cylinders, working as suction pumps or only compressors, converts the movement of buoys with the waves to a compressed fluid flow. And here, sea water is preferably used as fluid. This compressed fluid, collected in pipes, collectors, are used to drive a turbine type Pelton 12.

These Pelton turbines are suitable for high falling or high pressure and low flow capacity. The pressure of the water pumped is determined with design and construction. And for example, 100 or 200 Bars of pressures can be selected and jet on a Pelton turbine through a nozzle and make the turbine rotor turn at comparatively high speed. As it is known, generators are such machines that as their rotation speed increases, their moments and costs decrease. Especially, between turbine and generator having direct driving instead of having a gearbox, both decreases loss in the gears and bearings, so it increases efficiency, and decreases setup cost. Francis and Banki types of turbines can also be used but, because of the reasons above, Pelton turbines has more suitable characteristics than the others.

These kinds of turbines which can be used in hydroelectric power plants with high fall and low flow rate, are the ideal turbines for this invention because of the following reasons. To choose a structure working low flow rate and high pressured will be suitable for keeping loss of pressure low because, the water from the piston will not be continuously at constant speed and will pass through many connection parts. On the other hand, loss of power and efficiency are low in these kinds of turbines during flow rate and power changes. Namely, in the times both wave energy is high and low, the energy of the pressured water coming from pistons with a high efficiency of 80-90 % can be changed into mechanical energy with the turbine shaft.

And another important subject here is, because of these kinds of offshore systems will operate with a few crew or without a staff. So, the system should take its own precautions to evade the risks or continuing its operation. One of these risks is any leak or pressure loss from the pumping units or pressured lines. For such a case, on the drains which water is collected, there are valves which can be operated by the main control system. These valves can be solenoid, pneumatic or hydraulic controlled. The sensors located on the lines, will determine the pressure and momentarily flow direction. An unwanted pressure change or unexpected flow direction will feedback the main control system about where the loss is and the valve on that area will be closed automatically. The similar case is also valid for electric system.

An automatic control system over the platform will take care of the loading case in the generator, wave conditions on the sea, pressure at the nozzle, revolution number of the turbine, etc. and it will control some of the other parameters.

Fresh water can be used in case of circulation in a closed loop. Unlike in the case of working with fresh water, if sea water is selected as fluid, suitable constructions and materials will be selected for corrosion resistance. For example, in rotors and moving parts, bronze, stainless steel, aluminum resistant to sea water, or plastic materials should be used. Buoys and parts of platforms should need to be galvanized steel. On the other hand, method of cathodic protection will be useful to protect the construction. Sealing equipments, o-rings and packings should also be plastics, silicones and rubbers resistant to sea water's effects. And the lubricators should be suitable for sea water. As another choice, fresh water or hydraulic oil circulating in a closed loop can also be used. The sea water coming from pistons, will show important differences due to the conditions of sea and waves. An automatic control system should regulate the jet flow rate and jet velocity of turbine on turbine buckets (11). On the other hand, using multi jet peton turbine will be useful in case of adopting the differences in wave energy, namely the flow rate coming to the turbine. So, when big waves occurred, converting them into energy will be possible. Because of Pelton turbine's being suitable for high speeds, it can be directly connected to the generator directly without a gearbox. As the generator can supply electricity at standard, 50 Hz or multi phase, 60 Hz, also a DC generator can be used. So, from an offshore wave energy platform to the coast, one DC transmission line can be used. Circuit will be completed by using sea water as earth connection. When alternating current is used, as the condenser effect is eliminated, also turbine's and generator's working in a wide speed range and due to this using wave energy more efficient will be enabled. The DC, transported to the shore can be converted into 50 Hz or 60 Hz by using an AC generator driven by a DC motor or with using power electronics. In real applications many of these kinds of platforms will be arranged in an order. Having spaces between the platforms is useful to change direction due to the mentioned wave. One or more Pelton turbines will be over each platform. The energy supplied from these turbines will be loaded to the transportation lines, which are also the anchorage system of the platforms and preferably they will be at a determined depth. Platform series' having direction to the coast which energy will be transported, will let the power lines pass through the sea hanging to these platforms. This power line hanging in the water can also be located on the sea bottom. And where the platforms are not, the power lines can also be hanged on the buoys which are anchored to sea bottom. On the other hand, for evading overstress, the weight of the conductor should be carried by buoyancy of water. So, small lifting buoys can be located on the power lines. For example, the volume of the buoys which carries a conductor and its coating whose total weight is 30kg/m, will be designed as 29 It, the conductor will be carried largely by the water. By the way, the distance between two platforms or carrier buoys anchored to sea bottom can be large. For example these power lines can be passed through the sea, hanging to the buoys or the platforms, 30 m under sea level. For instance, in the case of there being 500 km between platform and coast and the conductor's being in depth of 30-80 m, the conductor's being hanged on the buoys at each 2 km, and having a coating filled with oil and foam, the weight of the conductor can be carried on with the buoyancy of water. As it is, sea traffic can easily flow over the power line. But, warning signs, for example metal plates, which can be noticed with sonar systems can be located for submarines.

For troubleshooting among the power line, a data signal line can be combined with the power line will be useful to detecting where the problem is. On the other hand, in the case of a failure, locating the emitters, which will notify where the power line is, will be useful for detecting where the line is. For example, when the emitters give the signal about the condition of the power line in their own region, a possible failure's location can be easily detected. This signal can be radio waves or sound waves. With the sensors and apparatus for hooking the cable over a service boat, the broken down part of the cable can be taken over the boat, repaired and put back into the water. In the case of a failure where it is known, beginning from the healthy parts hanged over two platforms or buoys, the power line will be hooked and an add-on will be located, so the problem will be solved. Locating wind turbines on these offshore platforms will also make the system economical. And also, adding the electric supplied from wind energy to the power line is possible. Supplying electric from wind will also be more economic at offshore platforms taking too much wind. Changing the direction of the platforms due to the wind and wave direction is necessary for the turbines to work efficient. Otherwise, the wind coming to the wind turbine will be slowed down and loose its energy at the previous turbine. If wind turbines are located on the platform to take the wind frontal (13), all turbines' changing direction independently from each other due to the wind will not be needed.

A suitable usage area of the energy supplied from these kinds of platforms is having systems which can use this energy located near or over these platforms. For example, this energy can be used with electrolysis method. With methods, which consume so much electric energy, such as aluminum electrolysis, magnesium electrolysis, or electrolysis of water to supply hydrogen, the electricity generated on these platforms can also be converted into chemical energy. Or, it can be used to gain oxygen or argon from air. If one of these two methods is used, there will be no need to have energy transportation lines to the coast. The hydrogen or oxygen supplied from these offshore platforms can be transported to the demanders on the coast with pressured tanks or by liquefactioning.

For example, with such a production, in a facility over one of these platforms, with electrolysis method uses dense electric power, a known raw material, an element or a metal, etc. will be purified, the electrical energy supplied will be converted to chemical energy, and it will be transported where it will be consumed. Or gasses such as nitrogen, argon, oxygen, etc. obtained by cooling the air under pressure, will be preferably liquefied, loaded on the ships and transported where it will be used.

This system will be built as it is possible to move these platforms to the safe places before the storms and to the suitable places due to the seasonal changes. For example, the platform will be unlayed from the buoys connected to sea bottom, and detached from the power lines to make it ready for transportation. At this time, both conductors and the ropes will be leaved as they are hanged on the buoys fixed to the sea bottom. Later on when the platform is brought back, the conductors and the ropes on the buoy will be connected to the platform and the system will be ready to use. Sometimes with natural conditions that these kinds of systems, which are generally designed for average conditions, cannot resist are faced. The threats coming such as storm or iceberg will be determined a few days ago and these platforms are designed to be able to be detached from their location and moved by tugboats to safe places. Here an important subject is taking away the platform from the hard natural conditions and bringing back to reconnect to the ropes, which lower ends are connected to sea bottom, without changing their position. Similar to this, without changing the position of the conductor passing through the sea, can be left as its one end is connected to the buoy. The platforms which were moved away will be able to be used when they are brought back and connected to fixing ropes and when the conductors are connected to generator outputs.

Claims

CLAIMS:

1. A method for converting wave energy into mechanical energy, characterized in that; employing an offshore platform and at least one articulated buoyant structure (1) which is being moved up and down by wave motion,

- employing pumping unit(s) (4,8) which is located between the platform and articulated buoy(l) and pumping water to a pressured water line by using buoy's wave action,

- collecting the fluid pumped, and conducting it through a water turbine by setting flow section and speed,

- rotating a Pelton, or Francis or Banki turbine which is located over an offshore platform and driven by the jet water's hitting turbine's blades or buckets,

- a generator coupled with a Pelton, Francis or Banki turbine, and driven by said turbine both are located over an offshore platform.

2. The method for supplying electricity from wave energy as claimed in Claim 1, further comprising the steps of;

- employing sea water as the fluid which is pumped - utilizing materials resistant to corrosion of sea water in pressured water lines, flow control vanes and turbine.

3. The method for supplying electricity from wave energy as claimed in Claim 1 and 2, further comprising the steps of; - corrosion protection means in metallic materials of the parts contacting with the sea water by employing a cathodic protection means or using anticorrosive coated steel, stainless steel, copper alloy aluminum alloy or plastics.

4. The method for supplying electricity from wave energy as claimed in Claim 1, further comprising the steps of;

- setting the flow's sectional at the turbine nozzle area by measuring the parameters of the generator and the turbine's number of revolutions, and/or water pressure, and/or moment of generator and turbine.

5. The method for supplying electricity from wave energy as claimed in Claim 1 , further comprising the steps of;

- controlling the valves by a control system on the pressured water lines from the pumps to the turbine,

- measuring the direction and/or the pressure of the flow on the pressured water lines from the pumps to the turbine by using pressure sensors for determining leakage, shutting down the section where the leak is by the valves in case of the sensors detecting loss in the pressured line, or having measurement outputs out of desired values.

6. The method for supplying electricity from wave energy as claimed in Claim 1 , further comprising the steps of; - compressing the working fluid in one side of the piston cylinder set and pumping into pressured line while sucking fluid into other side of the piston cylinder set in one stroke, changing compression and suction sides inside the cylinder during following stroke in opposite direction, - achieving pressured fluid flow toward the turbine during both upward and downward movements of the buoy(s).

7. The method for supplying electricity from wave energy as claimed in Claim 1, further comprising the steps of;

- providing horizontal projection areas of the buoys ratio of length/width being more than 1, - getting parallelism between the wave crest line and buoy's long side by changing the direction of the buoy according to the wave line,

- following wave crest line along whole length of the buoy,

- increasing efficient stroke of the buoys.

8. The method for supplying electricity from wave energy as claimed in Claim 1 , further comprising the steps of;;

- locating dampers and springs between the fixed and moving parts to the contact points where upper and lower limit points of the buoy's stroke.

9. The method for supplying electricity from wave energy as claimed in Claim 1 , further comprising the steps of;; locating more than one similar buoys (1) and piston-cylinder (4,8) groups in a consecutive order

- exploiting energy of the waves step by step by driving the consecutively ordered buoys (1) and piston-cylinder groups (4,8)

10. A platform located over sea for converting energy from sea waves, characterized in that ;

- having articulated buoys in a relatively movable manner according to platform,

- having a generator driven by at least one Pelton, Francis or Banki type water turbine

- platform's being over water with the groups of turbines and generators on it

- having ability to change the position of the platform itself or the buoys located over it.

11. The energy generation platform as claimed in Claim 10 further including;

- tied to the sea bed with the ropes, the ability to change its direction by using the ropes which are connected to sea bed.

12. The energy generation platform as. claimed in Claim 10 further including; connecting the electricity produced over it to the coast by the cables passing through the sea.

13. The energy generation platform as claimed in Claim 10 further including;

- using the electricity produced over it for cracking materials by electrolysis method on the platforms located over sea

14. The energy generation platform as claimed in Claim 10 and Claim 13, further including; producing hydrogen and/or from water by using the electricity supplied from wave energy

15. The energy generation platform as claimed in Claim 10, further including; - using produced electricity for obtaining nitrogen, oxygen and argon gas from air.

16. The energy generation platform as claimed in Claim 10 and Claim 12, further including; - passing the power lines through the sea in certain depth intervals by hanging them to the buoys which are fixed to sea bottom by ropes and/or

- using a buoyant coating or buoys located over the line in certain intervals for using the buoyancy of water to make water at least carry a part of the line's weight.

17. The energy generation platform as claimed in Claim 10 and Claim 12, further including; employing sensors situated along electric connection line for determination defects in power line between platform and coast.

18. The energy generation platform as claimed in Claim 10 and Claim 12, further including; generating means direct current

- preventing the condenser effect and impedance occurred in the case of alternative current line between the conductor and sea water.

19. The energy generation platform as claimed in Claim 10, Claim 12 and Claim 18,; converting DC to AC with an AC generator driven by an AC motor or power electronics at the end of the power line.

20. Rope used to tie a floating platform to the sea bed characterized in that; entire or some part of the weight of the rope's being carried by buoyancy of water and preventing the rope to be stressed with its own weight by placing carrier buoys on certain intervals over the rope or coating with a material lighter than water.