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Environment friendly energy solutions

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Changing the future

FloatNRG,

Coordinated Floating Energy Extraction System

Floating Wind Turbines and Islands



DESCRIPTION

 


BACKGROUND

  • The information as herein detailed were originally published under “Coordinated Floating Energy Equipment” (COFEQ) that extracts offshore renewable energies from sea waves, ebb/tidal currents, solar, thermal and floating wind turbines
  • The FloatNRG system is based on simple proven engineering principles that can be easily verified for performance and viability. It needed a Prototype scaled to 1:25, is proposed for testing system performance.

DESCRIPTION
The following summarizes the (COFEQ) system and stresses the floating wind turbines supports and utilization under the “Floating Energy” (FloatNRG) system as follows:

  • FloatNRG provides offshore coordinated renewable energy extraction, floating wind turbine supports, floating islands and floating causeways and highways.
  • The Structure Consists of a submerged ”Tension Leg Platform”- (TLP) anchored to the sea bed, to provide support for a modular “Floating Construction Unit”-(FCU) for extracting wave, solar, tidal and thermal energies.
  • TLP - Consists of modular “fixed floats“- (FXFL) provides support for the (FCU)’s, floating wind turbines, floating islands and floating causeways.
  • (FXFL)-1&2 are structural floats that may be replaced by tension wires.
  • (FXFL)-3 are the main floats that support the (TLP). Their top level is located at 1-m below the trough line of the highest wave, i.e. 6-m below (MSL). They are of modular construction, completely assembled at the shoreline with minimum cutting or welding. When assembled with the (FCU)’s and wind turbine, are floated and towed to location with all equipment ready for anchoring to the sea bed and ready for operation.
  • (FXFL)-WT is the main fixed float for anchoring and supporting the floating wind turbine.
  • (FCU)-modular construction completely assembled at the shoreline, on top of the (TLP) with all equipment installed and ready for operation. They are floated as part of the wind turbine support, or individually to location for anchoring to the seabed.
  • Dry Deck-forms a part of the (FCU). It is located at 6-meters above “Mean Sea water Level”-(MSL) and capable of handling 10-m high waves including seasonal and daily ebb/tide sea level variations.
  • Anchors (ANBLK)’s are made of marine hollow concrete blocks resting on the seabed using present designs, or using helical auger anchors driven into the sea bed.
  • Tension Lines tie the (TLP) to the anchor blocks.
  • Scalable The FloatNRG- is scalable to utility level and may be executed in phases, starting with phase-I for a single 6 MW wind turbine with all related marine extraction equipment, and upgraded to a 400MW floating wind farm.
  • Weights of the Structure, the (FCU)’s and (FXFL)’s depend upon selected structural materials and type of structural elements used.
  • Dimensions and configuration are adjusted to meet site location and project requirements.

FLOATING WIND TURBINE SUPPORTS
To appreciate the advantages of the FloatNRG system, compare the floating wind turbine supports as herein described with published data for existing systems. Two references are provided:
Existing Supports

  • 7 MW Mitsubushi Heavy Industries (http:www.mhi.co.jp)
  • The floating support area is a right triangle measuring 106x106x149.91-m giving a foot print area of 5,618 square meters.
  •  Floating Offshore Wind Platforms Consortia for web-Appendix-A.
  •  Typical functioning floating wind turbine system shown in Appendix-A.

Proposed Supports
Highlights and novelties of the (FloatNRG) floating wind turbine support are summarized as follows:
Comparison of Supports
Floating wind turbines for 240 Km per hour wind speed, existing and proposed by others are shown in attached Appendix-A, and summarized as follows:
Foot Print                  Weight                Uplift      Draft        Bending Moment              Resisting Moment
Sqm                           tons                     ton         m              ton-m ton-meter               ton-m ton-meter

Existing System
2,165                          N/A                     6,000      13.75 `       N/A                                     259,800
FloatNRG Proposed System
2,716                    1,871                      10,134        8.00          242,924                             250,103

  • The 1,871 tons weight can be reduced by 400 tons if fixed floats FXL-3 & 3a are constructed of marine steel instead of high strength marine concrete.

REQUIREMENTS

  • A 6 MW wind turbine has a total Nacelle weight of approximately 350 tons located 106 meters above sea level together with a 100 ton weight for its support.
  • 137,718 ton meters are developed at the floating wind turbine support by a storm with 240 Km per hour wind speed subjects, due to wind acting of the wind turbine, its support and (FCU)’s.
  • 38,722 ton meters are developed at the floating wind turbine support by the weight of the FloatNRG system.
  • 176,439 ton meter is the total bending moment.
  • 250,103 ton meter is the resisting moment developed by the floating wind turbine support.
  • Required factor of safety depends on local Codes.

Notes

  • Reducing the wind turbine base diameter from 14 m to 6 m would reduce the bending moment by 34 % at wind speed of 240 Km per hour,   giving a total bending moment on 153,282 instead of 176,439 ton meters.
  • Engineering and choice of materials play a major role leading to light weight supports, ease of fabrication, lower costs and ease of assembly at the shore line.
  • High waves, ten (10) meters should have minimum up/down forces acting on the floating wind turbine support.
  • Foot Print of the floating support is 2,108 square meters. This area should be used to extract marine energy from; waves, tidal and solar.

Bending Moments, fifty six percent (56%) are due to wind acting on the wind turbine, support and (FCU)’s. This leads to:

  • Composite Materials that would result in smaller WT support diameter, consequently less horizontal forces and bending moments due to wind action.
  • Improve the hydrodynamics of the WT support to reduce horizontal wind forces.
  • CONSTRUCTION and NOVELTIES
  • FloatNRG system is of modular construction, factory fabricated, completely assembled at the shore line including all equipment and the wind turbine ready for operation                                                . Novelty-1
  • Assembly when completed is floated and towed to location for anchoring to the seabed with no limitation to seabed depth.
  • Heavy Lift marine vessels and equipment are not needed.         Novelty-2
  • 3,312,923 KW-Hours per year are extracted from; marine and solar energy as detailed below under Table-1 Novelty-3
  • Floating Causeway is provided to connect adjacent wind turbines in an offshore wind turbine farm for vehicular traffic and for ease of maintenance and operation                                                          Novelty-4
  • Dry Deck area is provided for installing protective and control equipment related to wind turbine (relocated from Nacelle) and for marine energy extraction equipment.                                                       Novelty-5

FAR-FETCHED PROPOSAL
 Relocate the electric generator and respective protective and control gear from the Nacelle to the dry deck of the (FCU) to reduce bending moments, costs and improve operation and maintenance activities.      Novelty-6
ELEMENTS OF CONSTRUCTION
The FloatNRG is based on a well-known “Tension Leg Platform” (TLP) design. The assembled system has three elements as listed below and shown by FIG 1/6.
1. Active (FCU)-A units are installed at the front side of the prevailing wave/wind direction. These (FCU) units use buoyant floats to extract wave energy, use the roof to extract solar energy and hydro turbines to extract tidal energy and house energy extraction equipment, protective and control gear as detailed under FIG-3/6
2. Dummy (FCU)-D

  • Provided as support for the FCU-A unit.
  • Used to enhance the rigidity of the (TLP) structure,
  • Support for the solar energy extraction panels.
  • Support for the floating causeway for vehicular traffic. Novelty-7


3. Fixed Floats-(FXFL)
Fixed floats FXFL-1&2 may be replaced by tension wires to hold the structure together.

  • FXFL-1 running EW provide uplift and rigidity for the (TLP) system. They are marine steel pipes Ø 0.75 m. FIG 2/6
  • FXFL-2 running NS provide uplift and rigidity for the (TLP) system. They are marine steel pipes Ø 0.75 m. FIG 2/6
  • FXFL-3 & 3a are the main uplift floats of the (TLP) platform are made of high strength marine concrete measuring 2.5x48x5 m deep, spaced at 0.5 m apart to allow for up/down movement of wave water flow.
  • (FXFL)-WT is the main fixed float for anchoring and supporting the floating wind turbine.

 The top of FXFL are located at 6 m below MSL with wave front ends and bottoms are convex shaped to minimize horizontal and vertical forces due to wave action, by reducing the factor Cƿ for flat surfaces from 1.28 to 0.5 for round surfaces.
 The required length of 48 m may be achieved by modular reduced float size of 12 or 24 m by sectionalizing. FXFL1 & 2.
 The bottoms and tops of the (TLP) floats system are structurally held together.
 Two marine PVC pipes are provided to fill the fixed floats with water and to expel this water during towing of the assembled (TLP) structure to enhance stability during floating and towing to location.
 Alternate materials such as marine FRP or marine FRP pipes with structural reinforcement, and marine steel were investigated. The choice of materials depends on local availability, fabrication and cost.
4. FILP-1 water fill pipes to fill the fixed floats with water for reducing the height of the structure above (MSL) and improve stability during floating and towing to location.
5. FILP-2 air fill pipes to empty the fixed floats from the injected water and replace it with air when it reaches final location. Both FILP-1 & 2 are connected to a common compressed air header at the dry deck of the (FCU)-A unit.
6. TL-1 to 4 “tether lines” connect the (TLP) to the anchor block at the seabed
7. WR-1 “wrench assembly” at the (FCU) dry deck for lowering the (TLP) structure down to level where the center of the Dummy (FCU)’s is at (MSL) level.
8. Pull Lines (PL) for anchoring the (TLP) to the anchor at the seabed.
9. Anchors (ANBLK)’s are made of marine hollow concrete blocks resting on the seabed using present designs, or using helical auger anchors driven into the sea bed.
CHARACTERISTICS OF THE (TLP)

  • Detailed layout of the (TLP) is shown by             FIG-2/6
  • Center of Gravity is (CG) is below the center of buoyancy (CB) for stability of the assembled structure during towing.
  • Dimensions are provided as an example to give an idea about weights and uplift and moments of the system, as follows:
  • Summary per 1x6MW Floating WT


NOTES

  • 4.59 tons per Sqm gross uplift are provided by using 5m FXFL-3 & 3a.
  • 5.48 tons per Sqm gross uplift are provided by using 6m FXFL-3 & 3a.
  • Compressed Air energy storage of (4,688) cubic meters are provided at the (FXFL)’s at each 6 MW floating wind turbine support.
  • Space for installing 1 MW or more energy storage batteries is provided at selected (FCU)-A unit.
  • Net Uplift of 3.75 tons per square meter.

Comparison of the characteristics of proposed are shown below. Existing floating wind turbines are shown in attached Appendix-A.
Foot Print               Weight               Uplift                 Draft                Bending Moment                Resisting Moment
Sqm                       tons                    ton                    m                     ton-m                                 ton-m

Existing System
2,165                     N/A                    6,000                13.75 `                N/A                                  259,800
Proposed System
2,716                   1,851                 10,134                  8.00                 176,439                            250,103
 

Under storm conditions with wind speed of 240 Km per hour, existing floating wind turbine support gives a gross resisting moment of 259,800 ton-meters (6,000 x 43.3) compared to (250,103) ton meters provided by the FloatNRG system.
Output 1, 5x6 and 50x6 MW Wind Turbine Farms

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

­­CONSTRUCTION

  • Modular Construction, (FCU)’s are shop.
  • Assembly of the wind turbine support is done at the shoreline with minimum cutting and welding.
  • Transport of the assembly is then floated and towed to location for anchoring to the sea bed, ready of operation.
  • Comparison of weights are shown below.
  • Complete comparison is available upon request.
  • FXFL-3+3a Material Cost Comparison

DRAWINGS
The following are selected drawings to describe the FloatENRG system. Additional detailed drawings and calculation in active Microsoft XLS spread sheets are available upon request.
FIG 1/6 Complete assembly of the FloatNRG system
FIG 2/6 Submerged (TLP) system
FIG 3/6 Energy extraction system at (FCU)-A
FIG 4/6 Floating bridge
FIG 5/6 Floating residential island
FIG 6/6 Floating waste management island
Appendix-A Images of existing floating wind turbine designs, 3-Sheets

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