Floating Windmill ( A solution to present power shortages in Tamilnadu) Present By R Sugumar V Suriya Raja GS

Floating Windmill

Floating Windmill Network

Introduction A floating wind turbine is an offshore wind turbine mounted on a floating structure that allows the turbine to generate electricity in water depths. Introduced by Professor William E. Heronemus at the University of Massachusetts in 1972. 2/3rd of world is surrounded by water and so Offshore Wind resource is extremely abundant. China ranks first in producing energy by Floating Windmill.

Worldwide wind speed distribution

The Need Power Output from a wind turbine is proportional to the cube of wind velocity and to the square of the rotor diameter. The wind can be stronger up to 10 m/sec and steadier over water due to the absence of topographic features. Existing fixed-bottom wind turbine technology deployments had been limited to water depths of 30-meters. Worldwide wind resources are abundant over deep-waters. Wind should be steady and consistent for the smooth working of turbines.

Turbine Floaters Floating platform turbines can be classified into. Single-turbine-floater (one wind turbine mounted on a floating structures). Multiple turbine floater (multiple wind turbines mounted on a floating structures).

Basic idea A regular offshore wind turbine is placed over a 120 meter high floating concrete cylinder This structure is fastened to the sea floor with three sturdy anchor line The electrical power generated by the wind turbine will be transported by cable to shore or possibly to offshore oil platforms The windmills will be designed for water depths from 200–700 meters.

Basic idea The windmill will reach 80 meters above the sea's surface and will have a rotor diameter of about 90 meters. The windmill tower will be fastened to the concrete structure at about 12 meters beneath the sea Envision wind turbines with a power capacity of 5 MW and a rotor diameter of approximately 120 meters It's feasible to imagine offshore wind farms with up to 200 turbines and a combined power capacity of 1,000 MW. Steady winds in our part of the world could mean wind farms producing more than 4 TWh per year

Design For Anchoring Floating Structures Three types of engineered design for anchoring floating structures. 1. Tension leg mooring systems 2. Catenary mooring systems 3. Ballasted catenary configuration

Tension Leg Method

Catenary Mooring System

Ballasted catenary configuration

ANALYSIS AND DESIGN Some Special Characteristics Horizontal forces due to waves depends upon how the structure is connected to the seafloor. In framed, tower like structures ,the horizontal wave forces produce extreme bending and overturning moments as the wave forces act near the watersurface If the mooring lines form an angle with the vertical line, the horizontal stiffness and the forces increase ,hence design the system across leeward mooring lines are avoided Design is based on loadings due to permanent and variable loads or by fatigue strength due to cyclic wave loading & wind loading. Owing to the corrosive sea environment, floating structures have to be provided with a good corrosion protection system Load effects for fatigue analysis should be determined by considering all sea states that might be experienced by the structure and also due to Possible degradation due to corrosion or crack growth regular monitoring & maintenance is necessary.

MODEL TEST

ANALYSIS AND DESIGN

DESIGN CRITERIA Designing must based on serviceability and safety requirements for a service life of 100 years or more Motion characteristics include displacements, velocities and accelerations . Displacement are also considered for floating bridges For an underwater structure smaller damage may result in property damage which is expensive to repair , structural failures would be related to a major structural damage An overall stability of floating structures is considered in terms of overturning moment by wind only, and uprighting moment due to hydrostatics of the inclined body. Even damage to a few compartments does not seem to impose a stability problem Design checks using truly ultimate strength formulations

CORROSION PROTECTION Protection system includes coatings, cathodic protection, corrosion allowance and corrosion monitoring,overprotection may cause hydrogen embrittlement should be avoided. Cathodic protection is generally applied while coating methods are applied for parts shallower up to 1m depth. Of 1m below the water level ,the coating methods include painting, titanium-clad lining, stainless steel lining, thermal spraying with zinc, aluminium and aluminium alloy. The splash zone is the most severe with regard to corrosive environment and its upper limit zone is determined according to the installation of the structure. The ebb and flow zone corresponds to the next most severe environment but this zone does not exist for floating structures since they conform to the changing water level.

CORROSION RATE

Design Considerations for Mooring System To prevent the structure from drifting away under critical sea conditions and storms , hence the mooring system must be well designed We first select the proper mooring method, the shock absorbing material, the quantity and layout of devices to meet the environmental conditions and the operating conditions and equipments Behaviour of the floating structure under various loading conditions is examined Displacement of floating structure and the mooring forces do not exceed the allowable values

Mooring System

CONCLUSION: It requires less investment when compared to others, Ecofriendly , higher electricity production at cheap cost ,renewable and available all days and nights , Low noise emissions Advantages of operating in the offshore environment include higher and steadier wind speeds, less-restrictive acoustic requirements, and fewer space constraints

References: Kring, D., Korsmeyer, T., Singer, J. and White, J. (2000). “Analyzing mobile offshore bases Using accelerated boundary element methods,” Marine Structures, Musial, W.D.; Butterfield, C.P. “Future for Offshore Wind Energy in the United States” NREL/CP-500-36313 - Energy Ocean Proceedings, www.hydro.com www.magenn.com www.statoil.com

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