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Electricity generation by pilot realisation of a wave energy converter


The project objectives include the design, construction and/or manufacturing, installation, monitoring and testing of a wave energy converter system of the type that is described in patent No GR1000799/1992 developed by the Co-ordinator's team. The design work will be general, in order to provide the basis for the construction of a wide spectrum of such systems suitable for a variety of site conditions, as well as specific, to permit the construction/manufacturing, installation and test application results of a Prototype system.
The Prototype to be designed and implemented will include the following components:
A. Ten (10) hydro-air compressors.
B. The air duct system including the nonreturn valves.
C. A 25 m3 air-tank.
D. The converter system (air-turbine, R.R., electrical generator) and the power transfer system.
E. The monitoring system
The general design of the basic element of the wave energy conversion system, namely the hydro-air compressors, will provide the basis for implementation of such systems in a wide field of offshore cases with diverse sea wave climates.

The Prototype, on the other hand, is expected to demonstrate : a. Generation of up to 10 kW of electrical energy from ocean waves. b. The parallel utility of breakwater protection by the converter system because of its ability to function as a shock absorber against the impact of waves.
c. The capability to provide data and information and serve as pilot for the implementation of similar converters attached to floating breakwaters at harbours and marinas.

More specifically, the general design of the hydro-air compressors of the aforementioned converter system and the particular design of the Prototype to be constructed/manufactured, installed, monitored, tested, evaluated and operated in this project, will be accomplished, producing the deliverables specified below, where the deadlines for completion of the work of each organisation participating in the project is specified:
1.1 The general design will provide as deliverable the size and form of the hydro-air compressor of the converter system in relation to the sea wave spectra it can efficiently exploit, the air pressures it will develop, the stresses it can resist and the requirements for its mounting on the outside of an existing breakwater or cast together with a floating concrete pontoon for a harbour or marina.
The general design will be developed in two phases, namely the pre-design and the final design phase.

1.2 The design of the Prototype will adjust the general design of section 1.1 to the conditions of the site of application which is the breakwater at Akrokeramos harbour at Piraeus. It will cover all parts of the Prototype, from A to E, mentioned above, and all detailed planning for its implementation, namely, its construction/manufacturing, installation, monitoring, testing and experimental operation for a number of years. The design of the Prototype will be developed in two phases, the pre-design and the final design phases.

1.3 The data required for implementing section 1.2 will be gathered and analysed. These data refer to wind-wave and tidal spectra at the site of application, geometrical and physical parameters, such as height above sea level, construction material, availability and most suitable positioning of the prototype, etc., on the breakwater, water temperature and salinity, sea currents, history of collisions of vessels with the breakwater and other.

1.4 Part of the design work under paragraph 1.2 is the design of the 10 hydro-air compressors for the Prototype. Their design will aim at optimising the air volume to pressure ratio and at least two different types of compressors will be designed to secure maximum air volume intake, type one, and maximum pressure intake, type two.

The design of the hydro-air compressors will be developed in two phases, namely the pre-design and the final design phase.
The air transfer ducts, the non-return valves of the Prototype and the air tank, as provided by the patented arrangement will be designed in this phase. The non-return valves will be designed in a way that will secure minimal losses of air and maximum operating life. The air tank will have a capacity of 25 m3 and will be capable of sustaining internal air pressures of up to 5 Atm.
Upon completion of this part of the design the hydro-air compressors, the duct and non-return valves and the air tank, their construction will be subcontracted to the appropriate manufacturer.

1.5 The design of the electromechanical system, i.e. of the air turbine, the rotation reducer, the generator and the electricity transfer and distribution, will be such as to accept air pressures between 2 and 5 Atm and to deliver electricity at a power range of up to 10kW and potential of 220V. This system, although it will be installed offshore and operate under cover, should be designed in such a way as to resist martime environmental conditions.

1.6 The monitoring system, hardware and software, will be designed to offer automatic diagnosis and control by means of sensors, switches, screens and recording devices. It will also as record in readable and/or processable form information about environmental conditions and the condition of the Prototype. The monitoring system will provide readings and recordings of air pressure inside the compression chamber of all hydro-air compressors every T/10s, where T is the maximum wave period in seconds, of the operation of the non-return valves, of the pressure inside the air tank every T s, the rot./s of the air turbine, the power and voltage of the generator, etc.. These recordings will be readable by diskette in a form suitable for computer processing. The processing of the data to be recorded during the testing of the Prototype, will be designed and the corresponding software developed during this stage.
The design of the Monitoring system and the appropriate software will be implemented in parallel with the development of the design and construction/manufacturing of the Prototype, but in any case within ten months from the commencement of the project.

1.7 The evaluation of the design work (phase 1.2 through 1.6) and of the anticipated performance of the complete Prototype will serve both for improving the design of the various subsystems and for establishing performance criteria for the expected and the actual performance of the overall system. This evaluation of the design will review all design criteria and parameters and examine alternatives the available options for the improvement of the design.

1.8 The work at this stage includes installation of all systems on the site, on the floorplan provided in the design of the Prototype, their interconnection and checking and controlling each of them to ensure that they are in good condition and ready to operate as units and as an integrated system.

1.9 At this stage the Prototype will be put into operation and the functioning of each subsystem and of the entire system will be tested by direct observation and, mainly, the monitoring system. Monitoring will involve checking the behaviour of the Prototype, testing and parameter modifications, data recordings and their analysis and reporting at regular intervals.
Testing will continue for a period of two years.
With the exception of the first month, which will be part of this project, the remaining part of the testing period will have to be covered either by an extension of the project or another project.

1.10 The data and the report of stage 1.9 will be analysed and evaluated to establish the efficiency of the prototype and to provide recommendations for possible changes to increase its efficiency.

The co-ordinator of this research project and his associates have developed and patented (1992) a specific wave energy converter that combines the electricity generation utility with a heavy, concrete, floating and anchored breakwater serving as protection wall of a marina. Alternatively, the patented converter can be combined with an existing breakwater. This research project aims at a general design of a large application of the said converter in which a continuous row of hydro-air compressors will be fixed, at proper level, upon the side of the breakwater facing the incoming waves. The design includes definition of the compressed air transfer ducts, including inlet and outlet valves, of the air tank to which the compressed air will be transferred, of the air turbine to be driven by the compressed air of the air tank, of the reducer of the rotations delivered by the air turbine, of the generator connected with the rotations reducer, of the power transfer system and, finally, of the monitoring system of the overall wave energy converter. The design objective will be to deliver a converter system of 1MW power rate.
The research project includes also the design, constructing/manufacturing, installation and testing of a prototype converter based upon the said general design. The prototype will consist of 10 hydro-air compressors, a 25m3 air tank, the nonreturn valves and the compressed air ducts, the rotations reducer and the power generator. The prototype will be have a power rate of 10kW and will be installed at Akrokeramos breakwater of the harbour of Piraeus and precisely at the location of a vertical crack of the said breakwater. This choice is made in order to demonstrate the alternative utility of this converter, namely its capability to function as shock absorber against the wave action.
In fact, whatever wave momentum is converted to compressed air and then power is subtracted from the bill of the wave stress load applied upon the breakwater.

Funding Scheme

CSC - Cost-sharing contracts


University of Patras
Campus At Rio
26110 Patras

Participants (4)

Athena Hellenic Engineering Industrial and Tourist Co. SA
15231 Athens
Daedalus Ltd.
16675 Athens
Habitat Calabria Srl
Parco Fiamma 5
89126 Reggio Calabria
Model Farm Road Munster Institute
30 Cork