BACKGROUND-Energy Conversion
During the next 20 years, there is a need for 1,500 GW of new power plants.The fuel consumption for these power plants is estimated at 59 million barrels of oil per day. CO2 release to the atmosphere is estimated at 2.2 billion tons per year.The rising prices of fuel and gas.The requirement for all countries to have 20 % of its total energy needs to be from renewable sources by 2020 and need for clean energy,All dictate looking for renewable energy sources.
THE AIM
The following aims are required for a viable wave energy extraction system to produce maximum energy at minimum cost per KW-Hour:Generate electric energy suitable for connection to a public utility network , operated from a remote control center with network protection against power surges, transients and faults.System to auto-adjust to varying seasonal and daily intensity levels of renewable energy source(s).Use of equipment and materials that are readily available on the market, with a life span of 20 years plusInstalling equipment in an enclosed dry space to reduce equipment costs and costs of operation and maintenance.A modular supporting structure assembled at the shore line in a controlled area.Structure and equipment to resists severe storms, are modular in construction , can be assemble at the shore line with all related equipment and towed to installation location, ready for operation.
Coordinated offshore energy extraction SYSTEM, Wind, Waves, Tidal & Solar
WAVE ENERGY
A Float following the wave undulations through a pulley system and a continuous power line directly drives a set of rotary water pumps to pump a small quantity of water to a High Head and feed it to a closed circuit water flow through the Hydro Turbo Generator to generate electric power, step it up and transmit to the shoreline,A hydro Turbine is installed below the Wave Trough to extract energy from the Lee Side of the wave.
TIDAL ENERGY
The Wave Lee Side Hydro Turbine is also used to extract Ebb/Tide energy.
SOLAR ENERGY
The Roof of the “Construction Unit” is used as a support for Solar Energy system.
WIND ENERGY
A Wind Turbine is supported by a Floating Structure that forms an integral part of the COEE system.
CONSTRUCTION UNIT
A modular “Construction Unit” supports and houses the water pumps, the the Hydro Turbines and associated protective and control equipment.
Offshore wind turbines
Due to a multitude of reasons wind farms are being moved from Land Based systems to offshore.The huge weight of the foundations, its jacketing and settlement into the sea bed, necessitates another form of foundations.Floating foundations are now the trend.The logical design is a tripod floating foundation moored by catenary lines and anchored to the sea bed.Each Tripod is used as a “Construction Unit” for housing the COEE system, namely; Wave, Tidal and Solar Energy extraction.
WAVE ENERGY
Sun rays heat different areas of the Globe to different temperatures due to surface characteristics which heats up the respective air and induces air movement that acts on surface water particles in the seas and drags them to a higher elevation, consequently wave are produced. A reasonable Fetch of 400 Kilometers and wind speed is required to produce maximum wave heights.Wave energy consists of Potential and Kinetic Energies that are equal and estimated by the following formula.PE = KE = 0.50xHxHxTxWave Front in KWPE = KE = 0.50x3x3x9x1.5 = 60.75 KWFor a 3 meter high wave, a period of 9 seconds and a wave front of 1.5 meters.The maximum energy that can be extracted from a wave is 25% of the available energy. 65% of the extracted energy is converted to electric power due to hydraulic and electrical lossesThus the maximum electric energy that can be converted from available wave energy varies between 23 to 27 % depending whether a hydro turbo generator is used or a Variable Speed Generator is used respectively.This is provided so that no preconceived ideas are upheld
WAVE ENERGY DEFINITIONS
MSL meters Mean Sea Level, metersH = Wave Height of water between Crest and Trough mA = Wave Amplitude, equal H/2, mL = Wave Length, m Wave Cycle, Distance between consecutive wave crests, or wave troughs, 360 DegreesT = Wave Period for one Wave Cycle, Seconds
FLOAT
A Float, hollow, closed cylinder shape follows wave undulations and develops an Uplift Force of 2.605 tons with the following dimensions:.Diameter 1.50 m and a Height of 1.50 m, orDiameter 2.60 m and a Height of 0.50 m
The 2.605 tons Uplift Force is directly converted to mechanical energy by means of Power and Reversing Pulleys to drive reciprocating or rotary water pumps or a Variable Speed Generator.Increasing the weight of the Float would extract Potential Energy from the Lee side of the wave. However; this extra energy had been lost during the Front side of the wave.A continuous Pull Line is fixed to the bottom and to the Top of the Float to transmit the Float movement to the Power Pulley installed at the dry deck.The Float is protected against horizontal sway by making the Pull Line pass through a guide pipe installed as part of the FloatDifferent Float sizes were investigated. The selected sizes extract energy from waves as low as 0.50 m high. Using a large size Float would imposes larger supporting structure without increase in system efficiency.
WAVE PUMPS
A simple method is to use a reciprocating water pump with a small diameter to pump low head water to a higher head. This method needs a pump cylinder with a bore length of 8.50 meters to cover the piston movement of 8.0 meters for an 8 m high wave. This is not practical due to the pump size and to necessity of installing and supporting the pump under water. Therefore other methods were investigated.Using a Pulley system would reduce pump travel four times.
DIRECT DRIVE PUMPS & GENERATERS
Wave energy extraction was investigated by many who proposed different devices. None compares with the presently proposed System:The system is based on simple and proven engineering principles.The system extracts sea wave energy using wave undulations and a float that applies its uplift force directly through mechanical means to:Directly drive rotary or reciprocating water pumps, each pumping a small quantity of water to a high head, collect the pumped water and feed it to a hydro turbo generator, to generate electric power, orDirectly drive electric VSG generators, operate in parallel, step up voltage and transmit electric power to the shore.
A Floating or Fixed “Construction Unit” provides a dry deck and an enclosed space for all the equipment and associated power and control systems
UPLIFT, POWER REVERSING and POWER PULLEYS
The Up and Down movement of the Float acts on a Pull Line and converts it to rotary motion.A Power Reversing Pulley is installed below the wave trough to convert the Uplift Force of the Float to a Downward Pull.The Downward Pull acts on a Power Pulley installed at the dry deck above the water line to convert the Up and Down motion of the Float to Rotary Motion.A Reduction Gear increases the rotation of the Power Pulley to 1,800 RPM and drives a Reciprocating or Rotary water pump or a VSG generator.
WAVE LEE SIDE extraction - & TIDAL ENERGY
At the Lee Side of the wave, the water particles are moving down and have some Kinetic EnergyThis Kinetic Energy is extracted by Installing a hydro turbine below the wave trough line.The rotary motion of the Wave Turbine is transferred via a rod up to the dry deck to operate a water pump or a VSG at 1,800 RPM care of a reduction gear.The same wave Lee side turbine can be used to extract Ebb/Tide energyThis Hydro Turbine has unidirectional rotation
WATER FLOW
The water flow between the water pumps and the Hydro Turbo Generator is channeled through a closed piping system with necessary check valves.The Hydro Turbine uses a VSG generator to maintain required power supply frequencySuction pipes with check valves are installed to provide make up water to compensate for any leakage of water outside the closed circuit water flow system.
TIDAL ENERGY
Tidal energy is extracted using the same Lee Side Hydro Turbine for extracting energy from the Lee side of the wave.Shrouds are provide to increase the flow through the hydro Turbine and to provide unidirectional rotation during Ebb/Tide water flow The upward water flow at the front end of the wave does not reverse the direction of the hydro turbine rotation, as the resulting vector force is always in one direction
WIND ENERGY
Consists of a 6 MW Wind Turbine supported of a Floating Tripod, where each Pod is a Construction Unit consisting of Wave, Tidal and Solar Energy Extraction systems, (COEE).
Use a smaller size Wind Turbine up to 1.5 MW at each CURelocate the wind turbine from the top of the Nacelle to the Support base at the CU and use a VSG generator.The torque being mechanically transferred from the Nacelle at the top of the support to the bottom of the supportThis would provide better power control and waive the need for Invertors and associated equipmentThe capital, operation and maintenance costs would be reduced
Offshore wind turbines
Due to a multitude of reasons wind farms are being moved from Land Based systems to offshore.The huge weight of the foundations, its jacketing and settlement into the sea bed, necessitates another form of foundations.Floating foundations are now the trend.The logical design is a tripod floating foundation moored by catenary lines and anchored to the sea bed.Each Tripod is used as a “Construction Unit” for housing the COEE system, namely; Wave, Tidal and Solar Energy extraction.
SOLAR ENERGY
Solar energy is provided by using the roof of the CU as a supporting structure.The system is provided with pan and tilt facilities to extract maximum Solar energyThe DC power output is inverted to AC power and fed to the transformerThe area at the roof is 300 square meters.The solar system is provided with Tilt and Pan facilities for maximum capture of Solar Energy.
SCALABILITY
A set of four (4) pumps in line with the incoming wave can pump water at the average rate of 2 Liters per second to 181 LPS respectively for waves with 1 to 8 meters high over the whole wave cycleTherefor; ten (10) sets of four (4) water pumps are grouped together and installed on a modular “Construction Unit”The power output per “Construction Unit” varies from 7.15 KW to 791.96 KW respectively for waves with 1 to 8 meters highDWG shows 12 Construction UnitsFor large scale projects the Construction Units are arranged in V configuration to improve wave power leveling during the whole wave cycle and may be up to 1-Km wide.
CONSTRUCTION UNIT
A “Construction Unit” is provided to support the equipment on a dry deck above the water line and to provide an enclosed space for the COEE system equipment.The “Construction Unit” is of modular construction is assembled at the shoreline and towed offshore into position with all equipment installed and ready for operationThe “Construction Unit” supports ten (10) sets of four (4) pumps in a row together with a Hydro Turbo Generator, Step Up Transformer and associated power and control gear.The “Construction Unit” can be of the Floating or Fixed type structure and supports the following systems:.Wave Lee side turbine and Ebb/Tide TurbineSolar systemwind turbine
Thus you have a Coordinated Supporting Structure for the COEE system: Wave, Tidal, Wind and Solar.
MOORING
The “Construction Unit” can be of the Floating type or the fixed type where the supporting columns extend to the sea bed depending on project locationThe “Construction Unit” can easily handle waves in excess of 8 meters high. Elevating the water deck by an additional meter would extend the wave height by two (2) metersBoth types of the “Construction Unit” are capable of withstanding severe storms
CU WEIGHTS & UPLIFT – Excluding Wind Turbine
Total CU weight 16 TonsDesign loading Roof & Deck 42 tonsMaximum Pull Down Force 58 TonsMaximum Up Lift Force; at trough of 8- m High Wave 70 TonsMinimum Net Uplift at Trough of 8 m High Wave 12 TonsDynamic load due to Float action 42 TonsTotal Pull Down Force 101 TonsUplift by CU structure 107 TonsMinimum Uplift at Crest of 8-m High Wave min. 6 Tons, max 15 tonsThe above CU design minimizes the weight of the anchor blocks at the sea bed.
Kindly refer to Presentation file
