Wind Energy Overview
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Questions and Answers

Suggest an example in which you've encountered the use of wind as a power source?

Windmills, sailboats, wind turbines

What is the name given to the type of wind turbine that has its axis of rotation aligned vertically, perpendicular to the wind?

Vertical Axis Wind Turbine (VAWT)

Which of the following is NOT a type of VAWT?

  • Horizontal Axis Wind Turbine (HAWT) (correct)
  • Eggbeater VAWT
  • Darrieus VAWT
  • Savonius VAWT

    • Horizontal Axis Wind Turbines (HAWTs) are the most common type of modern wind turbines.

    <p>True</p> Signup and view all the answers

    Which factor is NOT directly related to the power output of a HAWT?

    <p>The color of the blades</p> Signup and view all the answers

    What is the name given to the design feature of wind turbine blades that creates lift force, similar to an airplane wing?

    <p>Airfoil design</p> Signup and view all the answers

    Which of these components is NOT typically found in a HAWT?

    <p>Solar panel</p> Signup and view all the answers

    What is the function of the yaw drive in a wind turbine?

    <p>To adjust the facing direction of the rotor (blades) to optimize wind capture.</p> Signup and view all the answers

    The brake in a wind turbine is used to stop the rotor for maintenance or to prevent damage in high wind conditions.

    <p>True</p> Signup and view all the answers

    Which of these is NOT a typical type of wind turbine tower?

    <p>Floating tower</p> Signup and view all the answers

    What is the primary factor that determines the size of a wind turbine, typically expressed in terms of its rotor diameter?

    <p>The power output it is designed to generate.</p> Signup and view all the answers

    Wind turbine size and power output are directly proportional, meaning larger turbines always generate more power.

    <p>False</p> Signup and view all the answers

    What is the primary advantage of using wind energy as a power source?

    <p>Wind energy is a renewable and emission-free source of energy.</p> Signup and view all the answers

    Which of the following factors does NOT contribute to the cost of wind energy?

    <p>The cost of solar panel components</p> Signup and view all the answers

    Wind energy is considered a suitable solution for completely replacing fossil fuels, as it can provide a consistent and reliable energy source throughout the year.

    <p>False</p> Signup and view all the answers

    What is the primary reason why wind turbines are often placed in coastal areas or hilly regions?

    <p>These locations generally have stronger and more consistent wind speeds.</p> Signup and view all the answers

    Study Notes

    Wind Energy

    • Wind is the movement of air in the atmosphere.
    • Wind energy originates from solar radiation (heat).
    • A range of surfaces on Earth absorb varying amounts of heat.
    • This heat causes air to rise up and cold air to flow back in.
    • Hot air rises and cold air falls creating wind.
    • Solar energy transforms into kinetic energy.

    History of Wind Energy

    • Windmills have been used in Greece and Denmark.
    • The Persian vertical windmill is an example of early wind energy technology.
    • The Chinese created vertical wind power water pumps.
    • The first wind turbine was invented in 1888 in Cleveland, Ohio by Charles Brush.
    • The turbine had 144 blades with a 17-meter diameter and produced 12 kW of power.

    Modern Development of Wind Turbines

    • Wind turbine rotor diameters increased from the 1980s and 1990s.
    • The power output of wind turbines has increased significantly.
    • Offshore wind turbines have been developed.

    Main Development for Wind Energy

    • Wind turbine scale increased.
    • Wind turbines moved from individual units to group operations.
    • The industry moved from private to commercialization.
    • The share of overall energy production increased.
    • Profit margins increased along with a reduction in running costs
    • Wind farms were integrated into existing power grids.

    Wind Energy Basic

    • Wind is the movement of air in the atmosphere.
    • The origin of energy is solar radiation (heat).
    • Earth's surfaces absorb varying amounts of heat which causes hot air to rise up and cold air to flow back down.
    • This creates kinetic energy.

    Variations in Wind Intensity

    • Wind intensity varies across latitude.
    • Friction with the earth's surface affects wind intensity.
    • Wind intensity is also measured as shear, turbulence, and laminar flow.
    • Hurricanes and typhoons are examples of extreme wind intensity.

    World Wind Resources

    • The distribution of wind resources varies across the globe.

    Availability of Wind Energy Resources

    • The worlds potential energy reserve of wind is 40 times the annual consumption and 5 times the current energy production.
    • It's available in all countries with more in coastal areas.
    • Wind intensity varies seasonally and daily.
    • Wind is an intermittent energy source of emission-free energy.

    Wind Power Calculations

    • Wind energy is calculated as 1/2 x density x (Area x velocity x time)
    • Wind Power generation depends on mass of air/density, velocity of air, the volume of air, and radius of the rotor.

    Limitation of Wind Power Generation Efficiency

    • A theoretical efficiency limit for wind turbines is the Betz Limit.
    • Maximum theoretical efficiency is 16/27.
    • Maximum Practical Efficiency is lower than 59%.

    Capacity Factor for Wind Power

    • The capacity factor for wind power is approximately 30%.
    • This varies based on site and turbine.

    Design of Wind Turbines

    • Vertical axis wind turbines (VAWTs) come in different designs like Darrieus, Savonius, and Eggbeater.
    • Horizontal axis wind turbines (HAWTs) are more common with designs including multi-blade, 3-blade airfoil and 2-blade small-scale designs.
    • HAWTS are the most common type of modern turbine.
    • Blades’ power output depends on length and blade design, either upwind or a downwind design..

    Interaction of Wind with Blades

    • Wind turbines use lift and drag force.
    • The difference in air flow velocity above and below a blade creates a lift force.
    • Blade angles are crucial for optimal lift production..
    • This is an airfoil design

    Design of a typical HAWT

    • A typical HAWT contains a tower, rotor, low-speed shaft, gearbox, generator, controller, anemometer, brake, yaw drive, high-speed shaft, wind vane, and nacelle.

    Blades Design

    • Avoid even number blades for stability.
    • Blades rotate to control optimal angle of attack.
    • Wind turbines decelerate during strong winds, using variable blade settings.
    • Wind turbines are often designed to operate at wind speeds up to 15 meters per second; higher wind speeds can be damaging.

    Nacelle, Shaft, and Generator

    • Nacelle houses the shaft and generator.
    • Low speed shaft connected to rotor and high speed shaft to generator, at higher rpms.

    Yaw Drive and Brake

    • Yaw drive controls the rotor's direction for optimal wind capture.
    • A brake is a mechanism to control and halt the rotor.

    Tower Design

    • Different tower designs include guyed towers, lattice towers, and tubular towers.
    • Tower size and design will affect efficiency and cost.

    Size vs Energy

    • The graph shows different sizes of wind turbines and their associated energy capacities.
    • Turbine size correlates with energy output capability.

    Location Consideration

    • Land-based wind turbines perform better on hillsides with higher windspeeds.
    • Countryside placement can be advantageous due to large flat areas, but medium windspeeds are favourable.
    • Urban and city areas are not ideal due to high rise building turbulence.
    • Offshore wind farms are in shallow water levels near coastal areas.

    Different Foundation Design

    • Foundation types include land-based, shallow water (types including Mono-piles, Gravity, and Tripods), transitional water, and deep water.
    • Foundation design varies depending on water depth and soil conditions.

    Shallow Water Foundation

    • Mono piles driven into seabeds are a common type of shallow-water foundation .
    • Gravity foundations are popular for offshore work, resting on the seabed.
    • Tripod foundations use multiple piles, commonly used by oil and gas companies.

    Deep Water Foundation Prototype

    • Deep water turbine foundations vary in design, and are a newer design technology compared to other foundations.

    Wind Turbine Design Consideration

    • Basic design parameters (including orientation and blade number).
    • Onsite survey of windspeeds and directions is required for turbine placement, ideally factoring in potential power generation.
    • Optimize the blade size for optimal efficiency.
    • Maximum operating speed parameters require complex systems to handle higher winds, due to increased noise and complexity.
    • Blade design parameters include angle of attack, lift/drag, characteristics that affect operational efficiency.
    • Wind turbine models/optimizations (computer simulations or small-scale wind tunnels) are needed to determine the best blade shape for operation.

    Current World Wind Energy Capacity

    • Shows how wind energy capacity has grown in the world and in the European Union region(EU).
    • The graph plots growth patterns over time.

    Cost of Wind Energy

    • Costs associated with lifetime of project and factors affecting cost of capital, capital costs, operation and maintenance costs are listed.
    • Overall cost of wind energy is related to factors including rotor diameter, hub height, physical characteristics, and site characteristics, also considering the annual energy production.

    How a 5MW Wind Turbine comes Together

    • Illustrates the different components of a 5 MW turbine and their approximate relative costs.

    Advantages for Wind Energy

    • Renewable energy source.
    • No emissions.
    • Vast potential energy reserves.
    • Safe operation.
    • Complementary energy source (can be combined with solar and hydro systems to produce more energy).
    • Potential use of peripheral lands for other applications (agriculture, industries, and transportation).

    Disadvantages for Wind Energy

    • Intermittent and unpredictable energy production.
    • Natural landscape disruption.
    • High initial cost of setup.
    • High cost of maintenance.
    • High cost of transmission lines.
    • High storage costs for off-peak use.
    • Threat to wildlife (birds).
    • Noise pollution.

    Discussion Question

    • Is Hong Kong suitable to adopt Wind Power? Questions will need to be raised about feasibility, and potential challenges including appropriate location, land availability and wind speeds. The question will require consideration of advantages and disadvantages, relative costs and local infrastructure.

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    Description

    This quiz explores the fundamentals of wind energy, its historical development, and modern advancements in wind turbine technology. Discover how solar energy is transformed into kinetic energy and the evolution of windmills from ancient to contemporary uses.

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