ELEC 5564 Electric Power Generation by Renewable Sources - Wind Power Notes

History of Wind Power

• Early Uses:
  • 5,000 BC: Egyptians used wind to sail boats on the Nile.
  • 200 BC: Chinese used wind-powered water pumps.
  • 600 BC: Persians used windmills to grind grain and pump water.
  • 1185: Windmill in Weedley, Yorkshire, was one of the earliest in the UK.
  • 14th century: Dutch used windmills to pump water out of rivers to prevent flooding.

Development Milestones for Wind Powered Generators

• Ancient Beginnings:
  • 5,000 BC: Wind was used to propel boats along the Nile River.
  • 200 BC: Wind-powered water pumps were used in China; windmills were used for grinding grain in the Middle East.
• First Commercial Windmill:
  • 1850s: Daniel Halladay and John Burnham created the Halladay Windmill.
• First Wind Turbine for Electricity:
  • 1887: James Blyth built the first windmill for electricity in Glasgow, Scotland.
  • 1888: Charles Brush installed the first wind turbine in the United States.
• Towards 2000:
  • 1981: The first commercial wind farm, "Towards 2000," opened, marking the beginning of commercial-scale wind power.
• Offshore Wind Energy:
  • 1991: Offshore wind energy gained relevance, starting in Denmark.
• Modern Wind Turbines:
  • Today, wind turbines are highly advanced, with large commercial turbines generating significant amounts of electricity.
  • Innovations in mechanics, aerodynamics, and control mechanisms have led to increased efficiency and reduced costs.

Global Installed Capacity

• In 2016, wind electricity accounted for 6% of the electricity generated by renewables.
• Levelized Cost of Electricity (LCOE):
  • In 2023, the global weighted average LCOE from newly commissioned utility-scale onshore and offshore wind projects fell.
    • Onshore wind projects: The global weighted average LCOE fell by 3% year-on-year.
    • Offshore wind: The cost of electricity of new projects decreased by 7% compared to 2022.

Advantages of Wind Power

• Renewable and Sustainable:
  • Wind is naturally occurring and inexhaustible.
  • Produces no greenhouse gas emissions.
• Cost-Effective:
  • Low operating and maintenance costs after installation.
  • The cost of wind energy has decreased significantly, making it competitive with fossil fuels.
• Energy Independence:
  • Reduces dependence on imported fossil fuels, enhancing energy security.
• Job Creation:
  • The wind energy industry creates jobs in manufacturing, installation, maintenance, and research.
• Scalable:
  • Wind power can be scaled to meet energy needs, from small residential turbines to large commercial wind farms.
• Offshore Potential:
  • Offshore wind farms can harness stronger and more consistent winds, increasing energy production.

Disadvantages of Wind Power

• Intermittency:
  • Turbines may not generate electricity when wind speeds are too low or too high.
• Grid Integration:
  • Integrating wind power into existing power grids can be challenging due to the variable nature of wind energy.
  • Requires advanced grid management and storage solutions.
• Maintenance:
  • Wind turbines require regular maintenance to ensure optimal performance, which can be challenging in remote or offshore locations.
• Initial Cost:
  • High upfront cost of manufacturing and installing wind turbines, although offset by low operating costs over time.
• Visual Impact:
  • Wind turbines can be considered an eyesore, especially in scenic areas or near residential communities.
• Noise:
  • The operation of wind turbines can generate noise, which may be a concern for nearby residents.
• Wildlife Impact:
  • Wind turbines can pose a threat to birds and bats, leading to collisions and potential fatalities.
• Land Use:
  • Large wind farms require significant land area, though turbines can coexist with agricultural activities.
• Potential Health Concerns:
  • Noise or shadow flicker of turbines can cause headaches and sleep disturbances.

Wind Turbine Types - By Blade Design

• Horizontal-Axis Wind Turbines (HAWT):
  • Most common type, with blades that rotate around a horizontal axis.
  • Efficient and commonly seen in areas with consistent wind patterns.
• Vertical-Axis Wind Turbines (VAWT):
  • Blades rotate around a vertical axis, allowing them to capture wind from any direction.
  • Often used in urban environments or places with variable wind directions.
• Offshore Wind Turbines:
  • Specifically designed for installation in bodies of water, typically in the ocean.
  • Take advantage of stronger and more consistent winds.
  • Often placed further from shore for higher wind speeds and greater energy output.
• Onshore wind turbines
  • Installed on land, typically in rural areas or open spaces where wind resources are abundant.
  • Convert the kinetic energy of the wind into electrical power

Wind Turbine Types - HAWT (Horizontal Axis Wind Turbines)

• The Horizontal Axis Wind Turbine (HAWT) has its rotor axis aligned horizontally to the ground.
• Typically feature 2 or 3 blades and are designed to face into the wind.
• The most commonly used type of wind turbine, particularly in large-scale commercial wind farms.
• Can be further divided based on the number of blades:
  • Two-Blade Turbines: Simpler and lighter but can experience more vibration and noise.
  • Three-Blade Turbines: The most common design, offering a good balance between efficiency and stability.
  • Multi-Blade Turbines: Often used in applications like water pumping, where high torque at low wind speeds is needed.
• The Siemens Gamesa SG 14-222 DD is a large offshore HAWT designed for generating significant power in wind farms.

Wind Turbine Types - HAWT: Blade Comparison

• 3 blades: The most common choice, offering the best balance of efficiency, stability, and performance.
• 2 blades: Best for smaller, cost- effective turbines but less efficient.
• 4 blades: Useful in specific conditions like low winds but comes with added cost, weight, and complexity.

Wind Turbine Growth

• 1185: The first windmill appeared.
• 1887: The first wind turbine in Scotland was created; turbines and mills were just 10 meters high.
• 1987: A 3.7MW turbine was built on Orkney.
• 2000s: Wind turbine rotor blades expanded hugely.
• Enercon E82: 4.2MW turbines emerged, standing as tall as St. Paul's Cathedral at 111m.
• Turbines grew to the height of the London Eye (135m).
• Soon after, the Gherkin at 180m.
• Then, the Eiffel Tower at 300m.
• 2025 (Projected): Turbines as large as the Shard will stand at 310m tall with installed capacities of between 13 and 15MW.

Wind Turbine Types - HAWT: Advantages and Disadvantages

• Advantages:
  • As the blades of horizontal axis turbines are perpendicular to the wind, they typically generate more electricity than other types of wind turbines.
  • Highly efficient and are not as expensive as vertical-axis turbines.
  • Highly reliable and have a high capacity (though this always relies on wind speeds in the area).
  • The blades’ rotational speed is usually high and consistent, making them often more profitable than other turbines.
  • The blades can tilt the rotor if storms are coming.
  • Controlling the angle of the blades is possible using the internal gearbox, giving you the best angle possible for harnessing wind.
• Disadvantages:
  • More vulnerable than different types of wind turbines need to shut down if wind speeds are too high.
  • The size of the structures is advantageous when it comes to capturing wind energy, but it comes with maintenance issues.
  • Because the generators are tucked inside the nacelle, they take longer to fix if a problem arises (in short, because maintenance workers need to mount the turbines).
  • The turbine requires heavy support for the blades at the base, meaning sizable cranes will be on a landowner’s property during construction.
  • They’re typically noisier than vertical-axis turbines.
  • They pose a risk to birdlife and bat life, as they can collide with the spinning blades.

Wind Turbine Types - VAWT (Vertical Axis Wind Turbines)

• In a Vertical Axis Wind Turbine (VAWT), the rotor shaft is positioned vertically.
• The blades rotate around this vertical axis and can capture wind from any direction, meaning they don't require a mechanism to face the wind.
• The Urban Green Energy (UGE) Vision 1500 is a small-scale VAWT designed for urban environments.
• VAWTs are often used in locations with variable wind directions, such as urban areas or small-scale applications.

Wind Turbine Types - VAWT: Types

• Savonius
• H Rotor
• Helical
• Darrieus

Wind Turbine Types - VAWT: Turbine Types

• Savonius Turbines: have an S-shaped design and are less efficient but can capture wind from any direction.
• Darrieus Turbines: have curved blades and are efficient but require an external power source to start.
• H. Darrieus: suitable for locations where wind directions are highly variable or turbulent known for its curved, aerofoil-shaped blades that rotate around a vertical axis.
• Helix-shaped wind turbine typically refers to a Vertical-Axis Wind Turbine (VAWT) that incorporates blades designed in a helical or spiral shape. The helical design of the blades allows the turbine to capture wind from any direction, making it more versatile in areas with variable wind directions.

Wind Turbine Types - VAWT: Advantages and Disadvantages

• Advantages:
  • Can maintain their rotation ability in turbulent weather and when wind speeds are lower.
  • Can function in any direction reducing the need to be facing the direction of the wind.
  • Easier to install and maintain than HAWTs, as the turbine generator is at the turbine’s base.
  • The blades don’t stretch as far as horizontal blades, meaning you can fit more turbines in the same area, can cluster into arrays
  • Suitable for urban areas.
  • Better aesthetics
• Disadvantages:
  • Lower Efficiency in High Winds. perform less efficiently in high-wind conditions compared to HAWTs. In strong winds, the turbine blades may not be able to capture wind energy as efficiently and they may even experience aerodynamic drag at high speeds.
  • Non-Self Starting- external assistance (e.g., a motor or an initial wind boost) to begin spinning.
  • Mechanical Stress and Wear: often experience uneven loading on their blades because of the constant changes in wind direction and turbulence, leading to increased mechanical stress. This can result in more frequent wear and tear, as well as higher maintenance costs
  • It’s also worth noting that VAWTs tend to sit lower than HAWTs, meaning they’re less productive.

Wind Turbine Types - Onshore

• Installed on land in areas with good wind resources.
• These areas can include rural areas, farmland, or high-altitude locations where wind speeds are typically higher.
• Turbines have large blades that rotate and drive a generator and generally have a capacity between $2.5-5$ MW.
• Onshore turbines usually have tower heights ranging from 80 meters to 150 meters (262 feet to 492 feet). Taller towers allow turbines to reach higher wind speeds, improving energy production.
• The length of the turbine blades can vary depending on the size and capacity of the turbine. Larger turbines used in utility- scale wind farms often have blades that span over 60 meters

Wind Turbine Types - Onshore: Advantages and Disadvantages

• Advantages:
  • Lower installation and maintenance costs than offshore wind farms because they don’t require specialized infrastructure like boats, platforms, and complex marine equipment.
  • Onshore wind turbines can be installed more quickly and with fewer logistical challenges compared to offshore turbines.
  • Onshore wind turbines help contribute to energy independence and reduce reliance on fossil fuels by providing clean, renewable energy.
  • Carbon-free and sustainable, making onshore wind turbines a key player in the fight against climate change.
• Disadvantages:
  • Wind energy is inherently intermittent, meaning that onshore turbines do not produce electricity all the time.
  • Large-scale onshore wind farms may face land-use conflicts, especially if they are located near populated areas.
  • Concerns over aesthetics, noise, and impacts on wildlife (such as birds and bats) may lead to opposition from local communities.
  • Transport and Installation Challenges: Transporting large turbine components to remote or hilly areas can be logistically challenging and expensive.

Wind Turbine Types - Offshore

• Installations are typically in shallow waters (up to 60 meters deep) but can also be located in deeper waters with specialized floating turbines.
• The goal is to minimize visibility and avoid interfering with shipping lanes, fishing activities, and recreational areas.
• Can generate between 5 MW to 15 MW or more per turbine.
• Tower height is typically higher (often over 100 meters), and the blade length can range from 60 meters to over 100 meters.
• Designed to withstand harsher marine environments, including saltwater corrosion, high winds, and strong waves.
• Offshore turbines have the advantage of being able to capture more consistent and higher wind speeds due to their location in the open ocean. This makes them more efficient and productive compared to onshore turbines.

Wind Turbine Types - Offshore: Floating vs. Fixed-Bottom Turbines

• Fixed-bottom turbines are anchored to the seabed in shallow water areas (up to around 60 meters deep).
  • They are the most common type and are similar in design to onshore turbines but built to endure offshore conditions.
  • The jacket foundation comprises a space frame structure assembled from steel tubular members
  • Usually fabricated in advance and transported to the seabed and piled there.
  • Despite being relatively economical in terms of steel consumption, jacket foundations can be expensive (storage, logistics, and installation).
  • In recent years, jacket foundations have been used extensively in intermediate depths between 5 and 50 meters.
• Monopile is typically found in water with a depth between 20 and 40 meters.
  • ease of manufacture, low cost, and manageable construction
  • utilized worldwide for offshore
• Floating turbines are designed for deeper water (greater than 60 meters) where the seabed is too deep for fixed-bottom foundations.
  • These turbines float on the water's surface and are tethered to the seabed with cables.
  • have been proposed and tested, benefiting from advances in the floating oil and gas platforms such as tension leg platforms (TLPs), semi-submersibles, and spars.
  • The world’s first MW-scale wind farm with a floating foundation, Hywind, with a capacity of 2.3 MW and a spar foundation, was installed by Statoil in the North Sea near Norway in 2009

Wind Turbine Types - Offshore: Advantages and Disadvantages

• Advantages:
  • Higher and More Consistent Wind Speeds: Offshore locations tend to have stronger and more consistent winds, allowing turbines to generate more electricity over time. This means greater energy production and a higher capacity factor
  • Reduced Land Use Conflicts: do not compete for land with agriculture, housing, or wildlife. This reduces the likelihood of land-use conflicts and aesthetic concerns that can arise with onshore wind farms.
  • Larger Turbines Offshore turbines are often larger than onshore turbines, allowing them to capture more wind energy and generate more power. This is ideal for large-scale, utility-grade energy production.
• Disadvantages:
  • High Installation and Maintenance Costs: Offshore wind farms have high upfront costs due to the complex logistics involved in installing turbines in the sea. Specialized ships, cranes, and equipment are needed to transport, install, and maintain these turbines.
    • The maintenance costs are also higher because of the harsh marine environment, where turbines are exposed to saltwater, strong winds, and corrosion.
    • Involves working in challenging conditions, and weather can delay projects, increasing costs.
  • Transmission and Grid Connection: Transmitting electricity from offshore turbines to the mainland can be challenging. Long- distance submarine cables are required to connect the turbines to the grid, which can be expensive and logistically complex.

Wind Turbine Types - Unconventional Designs

• Helical Blades: These blades are twisted along their length, providing smoother and more consistent torque. With a spiral- shaped design, these turbines are efficient in urban environments and can operate at low wind speeds.
• Flapping Panel Turbines: These use panels that flap in the wind, converting the motion into rotational energy.
• Shrouded Turbines: These have a duct or shroud around the blades to increase efficiency by directing more wind through the turbine.
• Ducted Rotor Turbines: These turbines feature a rotor enclosed in a duct that flares at the back, enhancing efficiency by directing airflow. They're also known as Diffuser-Augmented Wind Turbines (DAWT).
  • Archimedes LIAM F1
  • JetEngine wind turbine
  • FloDesign Wind Turbine

Wind Turbine Types - Unconventional Designs: Example

• 1,500 Kilowatt-hours production

Installation Legislations

• Planning and Zoning Regulations:
  • Minimum distance from residential buildings, roads, or other infrastructure.
  • In the UK, the distance between wind turbines and residential properties is not fixed but is subject to local planning policies and regulations. The specific distance can vary depending on factors such as the size of the turbine, the location, and local council requirements.
  • Wind turbines be set back a minimum of 300 meters from residential properties, may be as much as 500 meters or more.
  • For larger turbines (e.g., 3 MW turbines or larger), a larger setback distance may be required. In some planning decisions, a distance of 1 km from residential areas
  • Noise levels should not exceed certain thresholds at nearby residential properties (35–40 dB)
  • Shadow flicker no more than 30 hours per year, this could also influence the decision on where the turbine is located.
  • Areas such as National Parks, Areas of Outstanding Natural Beauty (AONB), or conservation zones, the setback distance can be significantly larger

Installation Legislations - Other Considerations

• Radar Interference