WO2018147753A1

WO2018147753A1 - Wave energy conversion device

Info

Publication number: WO2018147753A1
Application number: PCT/PT2018/000002
Authority: WO
Inventors: Kourosh REZANEJAD; Carlos Guedes SOARES
Original assignee: Instituto Superior Técnico
Priority date: 2017-02-09
Filing date: 2018-02-09
Publication date: 2018-08-16
Also published as: PT109903A; PT109903B

Abstract

The present invention relates to a wave energy conversion device with two oscillating water columns. The anterior, or front, column is the first to receive the contact of the incident wave system, which will then be felt on the rear column. The rear buoyancy module (4) in conjunction with the rear turbine (TO) and the rear chamber (2) limited by the intermediate dividing wall (6), by the lower plate (7) and by the upper plate (8), constitute the rear part of the system. The anterior buoyancy module (3), the anterior turbine (9) and the anterior chamber (1) limited by the intermediate dividing wall (6) and by the horizontal plate (5), aligned with the upper plate (8) and separated from this intermediate dividing wall (6), are fundamental elements of the anterior, or front, part of the device. The anterior and rear turbines (9 and 10) are independent and each one operates in each one of the two modules that constitute this converter.

Description

DESCRIPTION

WAVES ENERGY CONVERSION DEVICE

Field of the Invention

The present invention relates to a device for the conversion of. wave energy with two columns of oscillating water. The wave power converter (CEO) enables a reduction in the costs of producing electricity, increasing efficiency and decreasing equipment costs when compared to other congeners.

State of the art

Due to the limitations of fossil renewable energy sources and the fact that their process of producing energy increases environmental pollution, renewable energy resources have been attractive. Among renewable energy sources, wave energy is considered to be one of the frontier resources since a large part of the world's energy is concentrated in the oceans. The world 's available energy estimated by the World Energy Council is 17.5 PWh (PWh = Peta Watt per hour - IO ⁵² kWh, comparable to annual world energy consumption of 16 PWh (Boyle, G., 2004. "Renewable energy - power for a sustainable future." Oxford University Press).

There are several concepts and designs of wave power converters (CEOs), some of which are already implemented at sea, others have been built and tested at scale model. A large part of them are still in a development phase and others are still at a conceptual stage. One of the key challenges in CEO development is energy produced by these devices. Since the cost of designing, building, and maintaining these CEOs continues to be high and leads to uneconomical energy production compared to other available energy production equipment, a number of attempts have been made to invent more efficient CEOs. It is clear that the direct influence of the increase in efficiency is the reduction of the cost of energy production. Therefore, in the present invention there is the aim of reducing production energy through the simultaneous implementation of two different criteria. On the one hand, there was concern to design the device in such a way that it has a high primary efficiency for a wide range of wave frequencies. On the other hand, it was attempted to remove some more expensive parts of the device through the design of the plant. The new CEO can meet both requirements. It has a high capture width to convert energy from waves into pneumatic energy and, on the other hand, complicated control mechanisms have been removed. In fact, the occurrence of various types of hydrodynamic resonance mechanisms makes the conversion of wave energy into pneumatic energy highly efficient and not sensitive to the damping variations resulting from turbine dimensions. Consequently, the need to use complicated control systems in costly air turbines is eliminated. It should be noted that, in accordance with recent developments in the design of highly efficient air turbines applicable to a wide range of frequencies, as for example in patent application number US201113580099, "Turbine with radial inlet and outlet rotor for use in bidirectional flows", It is expected that the efficiency of transforming energy from waves to improved implementation of this new CEO project that has high primary efficiency values.

The oscillating water column device (CAO) consists of an open-ended coffin, which is partially immersed in water. The water column inside the chamber has alternating pressure fluctuations due to the incident waves. This flotation moves the air above the inner free surface of the chamber through the turbine, which induces the electric generator to produce electricity. The entire energy recovery unit is usually placed above the chamber and is therefore not in direct contact with the water. Several CEO devices have so far been devised to act on these bases and, consequently, can be categorized as CAO devices. Since the new CEO presented in this patent application can be considered as a CAO type floating device, all major prior inventions that are floating (or have the ability to become buoyant) and act as CAOs are reviewed, verify that any one of these inventions is not identical to the new CEO device that it is intended to protect.

Some of the designs of CAO devices act only as a floating CAO device although they may also be applied in power plants, such as CAO floating devices previously disclosed in GB20080007183, "Oscillating Water-Coal Wave-Energy Device Having a heiicai column "; US2QI00795008, ^M Wave power plant According to the Principle of the oscillating water column; "WO2011RU00540," Floating element of the wave station ", DE20101053300," Construct ion for converting wave energy into current ín eg ocean, has floaters attached at steel frame, swot-oscillating water column system for driving construct ion, and frames ie steel pipes, weided together ";CN20132442966U," Offshore oscillating water column power generation device ";GB20140Q12997," A wave energy converter ".

In some plans of floating CAO devices, multiple cameras have been implemented, for example in the floating CAO devices previously described in the following patent applications: FR19780028577 - "Sea wave energy converter - uses hollow floating chambers with open bottons, which purap air to drive turbines "; CA19992286545 - "OWC energy center"; WO2012ES00050 - "Floating structure and installation for using the energy of the waves surge, using a floating catamaran with severea1 oscillating v / ater column chambers"; US20Q50658722 - "Modular near-shore wave-powered energy collection system"; US20070300462 - "Wave energy generator"; DE2009.1008211 - "Wave-driven power station for converting wave energy into usable energy, has openings on its iower side or is open downward, so that the water. US20090994585 - "Energy converter"; GB201200Í3884, "Plural OWC system with angled ports"; WO2005GB01166 - "Wave energy conversion apparatus"; GB20090009S01 - "Wave energy generator with multiple turbines". These plans contain at least two chambers where a column of trapped water oscillates within them. By applying this concept, it would be possible to increase the production energy from waves although the manufacturing cost of the plant is also increased. For this, an economic analysis and justifications should be applied in order to evaluate the cost of the energy produced before starting the construction of the plant. It should be noted that each chamber of these CEOs has its own frequency of resonance, and hence the application of their combined systems on a platform increases the frequency bandwidth with improved efficiency. It should be noted that the system can absorb almost all the energies of incident waves when the phenomenon of resonance occurs in the chamber. Thus, the system improved the efficiency at this resonant frequency. In the case where the CEO has several resonant frequencies the system has high efficiency values at each of these frequencies (and probably in the frequency ranges between them) which eventually leads to a total increase in the high frequency efficiency of the bandwidth.

A specific CAO floating device was invented by Masuda and Toshiari and is disclosed in patent application No. EP19990302807 - "Wave energy absorbing the oscillating water coiumn type", and is referred to as a backward bent conduit (BCET). The presence of reverse traction force for specific frequency ranges of incident waves that cause the device to move towards the waves is one of the unique advantages of this type of floating CAO device. This negative movement force substantially reduces the anchoring forces. Additionally, the efficiency of the device is high due to the occurrence of relative movements between the device and the water trapped within. However, the area of incoming waves within the BCET device is located downstream. A similar plan of BCET device was introduced by Mccarthy Mikhael John Martin & Whelan Michaei Martin in patent application No. US20070446095- ^VV The floatabie wave energy converter and the methcd is impractical of the effectiveness of the floatay wave energy converter. "The device has three air chambers to the located in the compartment and three corresponding water accommodation channels.

The basic idea of the design of some wave energy converters was focused on the implementation of combined plans of various types of current wave, wind and current energy converters together and integrated into a platform that will likely lead to the reduction of energy costs produced by the plant . With this knowledge, the meaning for the energy absorption of the waves may be a oscillating water column device, such as those described in the following patent applications: WO1993G3Q2072 - "Combined wind and wave power generator"; US20070311527 - "Wave and wind power generation"; CN2014144 ^' 8,186 - "Offshore wind turbine platform combined with oscillating water column type wave energy device"; DE201110.118254 - "Combined off-shore energy plant for producing wind and wind energy to be converted into electric energy, has wind turbine and / or wave turbine mechanically coupled with each other and connected with generator the function of sensor system"; GB2006Q02066S A ^N Combined water current and wave energy powered installation "; GB20000019235 -" Offshore power generating structure "; DE1995104356 -" Multiple system. wave energy converter for electricity generation ".

Summary of the invention

The present invention relates to a new wave energy converter with. two columns of oscillating water, the anterior and the posterior, relative to the incident waves.

The device, object of the present invention, is constituted by: The anterior oscillating water column system located downstream of the waves comprises the following elements: an anterior chamber (1) delimited at the base by a horizontal plate (5), and at the top by a front turbine (9), being is connected to an intermediate partition wall (6) on the right side, and to an anterior flotation module (3) on the left side;

The rear oscillating water column system comprising the following elements: a rear chamber (2) delimited at the base by the lower plate (7), and at the top by a. (10) being connected to the intermediate partition wall (6) on the left side, and to a rear flotation module (4) on the right side, which is delimited at the top by a top plate (8).

The device may be anchored to the seabed by catenaries or anchor lines with clearance or by combining both.

On the other hand, the front flotation module 35, the horizontal plate 5 and the intermediate partition wall 6 are fundamental members of the previous CAO. Each of the CAO of the CEO is intended to absorb the energy of the surface waves with specific wavelength bandwidth ranges Cu, in the frequency ranges where the movements of the device or the water trapped in the interior are magnified (due to the occurrence of resonance), the back will have a dominant role in the absorption In this situation it is anticipated that a reduction in the mooring force due to the negative action force of the wave drift acting on the back device should occur. oscillations are small, the previous CAO must absorb most of the energy from the incident waves.

Consequently, the dimensions of the front chamber 1 and the horizontal plate 5 must be determined so as to impose resonant conditions on the water column within the front chamber 1 which will cause the efficiency of the apparatus to increase. Therefore, the appropriate actions of each part of the new wave energy converter (CEO) give rise to a more efficient frequency band which covers the entire range of frequencies typical of wind and wave waves. In this situation, it is anticipated that the implementation of complicated control tools to establish phase control or other active and reactive approaches can be eliminated by using rate constant speed turbines. The four resonance mechanisms, including resonance of oscillations of the device, the resonance movement of the CAOs inserted inside the anterior chamber (1) and the posterior chamber (2) and, finally, resonance resonance dedicated to the influence that the horizontal plate (5) extending horizontally outwardly from the front chamber (i) provides a highly effective capture width ratio for the device.

Detailed description of the invention

The present invention relates to a new wave energy converter with two columns of oscillating water, the anterior and posterior, relative to the incident waves.

(b) the rear oscillating water column system comprising the following elements: a rear chamber (2) delimited at the base by the lower plate (7), and at the top by a rear turbine (10, this latter being connected to the intermediate partition wall ) on the left side and a rear flotation module (4) on the right side, which is delimited at the top by a top plate (8).

In the present invention, the front turbine (9) is dedicated to the front oscillating water column system and the rear turbine (10) is dedicated to the rear oscillating water column system, which allows optimizing each turbine for the operating conditions of each system.

The device may be anchored to the seabed by catenaries or anchor lines with clearance or by the combination of both.

The main criterion in the development of renewable energy devices is the cost of energy production. In this regard, in the field of wave energy converters, several attempts have been made to reduce the cost of energy production by implementing various techniques, such as increasing the efficiency of the apparatus, incorporating CEOs into multiple objective platforms to share the costs of construction and maintenance the various independent parts of the platform, removing more expensive parts of the device by implementing appropriate economical tools, optimizing plate design which eliminates the need to use expensive apparatus for the apparatus, implementing various types of renewable energy instruments in a platform, the implementation of maritime CEOs in wave parks, which reduces the cost of transferring the energy produced, among others.

The general concept of the new CEO presented in this invention is illustrated in Figures .1 and 2. It is intended to be applied in the above mentioned techniques and simultaneously in this new CEO. In fact, the plane is the combination of the CAO with the border port, which configures the horizontal plate (5), and the subsequent CAO device. The two front (3) and rear (4) float modules of the CAO provide buoyancy of the device and proper mooring lines hold the apparatus in position as shown in Figure 2. The device's anchor cables attach to the anchor (13) and can also be equipped with a flotation module (11) and a ballast module (12) as shown in Figure 2.

The prior CAO system includes the following components in Figure 1: front chamber 1, front flotation module 3, lower plate 5, intermediate partition wall 6 and front turbine 9. The water columns attached to the front chamber (1) and above the port of the horizontal plate CAO (5) have two different specific resonant frequencies.

It is evident that the performance of the system is approximated to the highest value of these resonant frequencies and, consequently, the system absorbs energy from almost all incident wave frequencies. In this case, these dimensions of the CAO and its port are designed properly; its two resonant frequencies may occur with appropriate frequency ranges between each. In this situation, the efficiency drop is very small among these resonance mechanisms as demonstrated by Rezanejad et al (Rezanejad, K., Shattacharjee, J. and Guedes Soares, C., 2013. Stepped down bottom effects on the efficiency of nearshore osciliating water column device, Ocean Engineering 70, 25-38). Accordingly, the apparatus has high primary efficiency values in the frequency range of these resonance phenomena. Since the primary efficiency of the apparatus in the resonance condition is not very sensitive to the variation of the damping coefficient of the turbine, the previous turbine {9} with appropriate damping constant can be implemented for the previous CAO system. In this situation the efficiency of the apparatus is maintained at the highest possible values while expensive turbine control instrumentation is eliminated. It should be noted that the previous CAO system will have high efficiency values only when the device movements are very small as demonstrated by Rezanejad and Guedes Soares (Rezanejad, K. and Guedes Soares, C, 2014; Numerical study of a floating (1998), pp. 951-9605, pp. 951-9605, pp. 951-9605, pp. 951-9605, pp. 951-9605 To compensate for this limitation, the later CAO system is incorporated into the CEO device as a complementary part of the handset, which will play an important role in these situations. The rear CAO system includes the following elements, as shown in Figure 1: rear chamber (2), rear float module (4), intermediate partition wall (6) which is the connection between the front and rear CAO systems, (7), top plate (8) and rear turbine (10). The posterior CAO has the task of absorbing energy when the movement of the apparatus is considerable and the previous CAO system can not absorb the energy of the waves. In other words, by simultaneous application of the anterior and posterior CAO systems, two different mechanisms are explored where the anterior system is effective with small float movements and the posterior one is active for larger movements. It should be noted that, unlike the previous system, the posterior CAO is not efficient when the movements of the apparatus are small, as proved by Rezanejad and C. Guedes Soares (Rezanejad, K. & Guedes Soares, C. 2015. Hydrodynamic (1987), Taylor and Francis Group, London, UK, pp. 1287-96).

In fact, the relative movement of the posterior CAO with respect to the water column inside the rear chamber (2) is the source of wave energy absorption. For this reason, the rear CAO does not collect large amounts of power when the float has small movements. The water trapped inside the rear chamber (2), together with the movements of the apparatus (pitch movement relative to the free surface of the waves), has different specific resonance frequencies. At each of these resonance frequencies, (Rezanejad, K. & Guedes Soares, C. 2015. Hydrodynamic performance assessment of a floating oscillating water column. Maritime Technology and Engineering. Taylor & Francis Group, London, UK. pp. 1287-96). If the dimensions of the back of the device are designed so that their resonant frequencies are distributed at appropriate frequency ranges, a wide band of the high efficiency curve can be produced. This high efficiency wideband curve covers almost all frequency ranges of wind and wave, which in principle leads to a considerable increase in energy generated by the apparatus.

The main aspect of the operating principle of the device is that the movement is small in the resonant frequencies of the previous CAO system absorbs wave energy as an active part while the back does not receive high amounts of energy in this situation. On the other hand, at the back resonance frequency, the anterior system does not absorb energy from the waves in an effective way and most of the energy is absorbed by the back. It should be noted that the negative drift force can occur for the pitching resonant frequency apparatus which considerably reduces the mooring loads as demonstrated by Masuda Yoshio & Kuboki Toshiari in the patent application No. EP19990302807 - "Wave energy absorbing of the oscillating water coiumn type ". As in the previous CAO, a rear turbine (10) with the appropriate coefficient of constant damping can be installed in the rear CAO, eliminating the need to use costly control tools without a greater interruption in the amount of energy captured from the waves.

Figures 1 and 2 show the typical plan of the new CEO converter introduced in this invention. How can it be confirmed? through the figures, each one. of the front and rear CAO systems have their own turbines: the front turbine (9) and the rear turbine (10). Thus, the pressure inside the anterior chamber (1) of the CAO and the rear chamber (2) may be different. These pressures have a radiation effect and consequently the hydrodynamic interaction occurs between the chambers, which may be beneficial to implement further improvements in the efficiency of the apparatus by CAO systems with. i-chambers.

In addition, a failure in the anchor lines is one of the main challenges in the design. Since the new CEO includes a later CAO, it is expected that, at different frequencies, the inverse drift force acts on the structure causing the force to decrease in the anchor lines and prevents the failure of those lines, which is an advantage of this CEO .

Description of the figures

Figure 1 shows the schematic cross-sectional plane of the new double CAO (first plane) wave energy converter.

Figure 2 shows the schematic 3D plane of the new wave energy converter.

Lisbon, February 7, 2018.

Claims

A wave energy conversion device, characterized in that it comprises:

(a) a front oscillating water column system located downstream of the waves comprising the following elements: an anterior chamber (1) delimited at the base by a horizontal plate (5), and at the top by a front turbine (9), being is connected to an intermediate partition wall (6) on the right side, and to an anterior flotation module (3) on the left side;

(b) a rear oscillating water column system comprising the following elements: a rear chamber (2) delimited at the base by a lower plate (7), and at the top by a rear turbine (10), which is connected to the partition wall (6) on the left side and a rear flotation module (4) on the right side, which is delimited at the top by a top plate (8).

A wave energy conversion device according to the preceding claim, characterized in that the front turbine (9) is dedicated to the front oscillating water column system and the rear turbine (10) is dedicated to the water column system rear oscillator.

A wave energy conversion device according to the preceding claims, characterized in that it is anchored to the seabed with the use of catenaries or anchor lines with a clearance or a combination of both.

Lisbon, February 7, 2018.