Putting it All Together
Putting it All Together
- The system was originally developed as “Coordinated Offshore Energy Extraction” system (COEE) for extracting renewable energies form: waves, tidal, solar, thermal, and wind.
- With slight modifications, by adding fixed floats the (COEE) system can be used as a floating support for offshore wind turbines.
The fixed floats were further used to provide compressed air storage reservoir. This was enhanced by adding floating compressed air reservoirs behind the (FCU)’s.
- The large volume of compressed air reservoirs of 4,320 cum (3,420+900) per (FCU), led to its utilization as “Compressed Air Energy System” (CAES) developed by others for use with a power plant.
A 100MW wind farm can provide compressed air storage reservoir of 500,000 to 600,000 cum depending if 3MW or 7MW wind turbines are used. This entices developers and owners to install a floating conventional power plant.
- Additional fixed floats would provide space and support for a floating conventional power plant of the order of 100MW.
- The above modifications led to changing the name of the system from (COEE) to (COFEQ) as described in the heading of this proposal.
- Solar energy equipment are installed on an area of 776 square meters; 551 sqm (24.5x22.5) at the roof of the (FCU), and 225 sqm on the floating compressed air reservoir (22.5x10), giving a total floating surface area of 77,000 square meters for solar farms.
- The DC output of the solar system is conditioned and fed into the common DC bus at the (FCU).
Floating Wind Turbines
- Two rows of (FCU)’s are installed with alternating active and dummy floating units to give a foot print area of 1,102.5 square meters (2x 24.5x22.5).
- Fixed floats are added below the trough line of the wave to provide for each (FCU):
- An uplift of 122.5 tons by the cross floats; 5x (24.5x1x1).
- An uplift of 3,420 tons by the lateral floats; 9.5x2x (22.5x2x4).
- The total uplift of 3,542.5 tons for the active and dummy (FCU); that is; 3.21 ton per sqm, partially support the floating wind turbines rated 3 to 7MW.
- The fixed floats may be used as compressed air storage reservoir providing a volume of 3,542.5 cubic meters of compressed air storage space.
- An additional uplift of 100.53 tons is provide for 3MW wind turbines by extending the wind turbine support 8m below the trough line of the wave (3.1416x2x2x8), (πxrxrxD);
- Or an additional uplift of 226.2 tons is provide for 7MW wind turbines by extending the wind turbine support 8m below the trough line of the wave (3.1416x3x3x8), (πxrxrxD);
- Floating wind turbine spacing is 100m (four (4) active and dummy (FCU),s) for 3MW and 200m (eight (8) active and dummy (FCU),s) for 7MW.
A file with multi spread sheets is developed as follows:
- Page-1 to enter all possible variables of the system as shown with yellow background for wave characteristics; wave heights, buoyant float size, water pump size, (MSL), wave period, MSL level, materials and working head.
- The uplift force developed by the (BF) has to accelerate the weight of the (BF) moving parts and the weight of the water in the pump and develop the total TDH of the water.
- Page-2 automatically computes the respective response of the system to the data entered in Page-1. The formulae are locked to prevent inadvertent entry of data. It computes the incoming wave energy, the water pumped and respective head, the (BF) movement, the energy extracted by each (BF) 1 to 4, individual and total power output in KW for different wave heights for each pump or generator and for the total power for pump sets 1to 4.
Energy and Power Output
The energy and power output per one (FCU) is as shown in the following table-1
Foot Print Peak Output Output/FCU
System Description meters KW/FCU KW-H/Year
Wave Energy Ø-2m Variable float, 22.5x24.5 260.4 864,000
Tidal Energy, eight (8) Ø-2m 8x4 KW 32.0 233,333
Solar Energy, 30% efficiency 796.25 238.9 749,828
Wind Turbine 3MW/ 4 FCU 4,410 SQM 750.0 2,250,000
The above data depends upon sea and wind states and the available hours of sunshine per year.
Using water pumps results in low system efficiency due to:
Hydraulic losses in the water pump, in the closed circuit piping system and in the hydro-turbo generator. This choice of system is leads to reduced efficiency and the use of an electric generator is proposed.
The (COFEQ) system looks like an offshore wall far away from the shoreline.
Openings in the (FCU) are be provided to reduce horizontal wind forces.
System Advantages and Improvements
The (COFEQ) has the following advantages:
- The system uses simple engineering principles and equipment developed by others that are readily available on the market with proven quality and performance.
- A fully coordinated offshore energy extraction (COEE) system for extracting renewable energies from: waves, tidal, solar, thermal and wind.
- The roof of the (FCU) is used as support for solar energy. Battery storage system is installed at the (FCU) deck to provide energy storage and continuity of DC supply.
- The system (FCU) is assembled on the shore line, floated, towed to location and moored to the seabed with all equipment ready for operation.
- The system practically provides free floating supports for offshore wind turbines.
- The relocation of the step-up gear from the nacelle to the bottom of the support of the wind turbine, greatly reduces bending moments at the base, reduces construction, operation and maintenance costs,
- The (COFEQ) system provides fixed and floating reservoirs for compressed air energy storage in excess of 500,000 cubic meters for 100MW offshore wind farms.
- The (COFEQ) provides a floating bridge suitable for vehicular traffic for ease of construction, operation and maintenance.
- The (COFEQ) provides for floating power plant installation.
- It provides suitable lodging for operation and maintenance personnel.
Extending to a Large Scale System
- The system provides four (4) (active and dummy FCU)’s for 3MW wind turbines and eight (8) (active and dummy FCU)’s for 7MW wind turbines.
- The (COFEQ) system when used in conjunction with a 100MW offshore wind farm provides compressed air reservoir storage capacity between 500,000 and 600,000 cubic meters.
- The freely provided volume of 500,000 to 600,000 cubic meters reservoir capacity at a 100 MW offshore wind farm, entices developers and owners to use this facility to provide a 100MW gas-turbo power plant with "compressed air energy storage" (CAES) to operate at a higher efficiency and provide sizeable energy storage facility. This is achieved due to reduced power needed to compress gas-turbine inlet air.
- Installing an offshore floating 100MW power plant would provide security to the project site and would free the project from political and local influence that may contribute to the failure of the project. .
Return on Investment (ROI)
- The challenge for owners and developers is to request Developers and Contractors to provide an Alternate Bid based on the (COFEQ) as herein described. Tis would provide a practical way for Bid Analysis and choice of an improved system.
- The cost of the project and the income based on the electrical energy produced per year and the sale price of one (1) KW-Hour would determine the Return on Investment, which is estimated above fifteen (15%) percent.
- The project is practically self- financing.
hamil Ayntrazi, PE
Bsc. Elect'l-AUB, MBA-NY,
Registered Prof. Engineer, Lb. & N.Y
Hion Joon Kim