Exploring Offshore Wind Energy (Student Guide)

20

21

Exploring Offshore Wind Energy

-20

22

Student Guide

SECONDARY

Introduction to Wind and Energy What is Wind?

Wind is simply air in motion. It is produced by the uneven heating of the Earth’s surface by energy from the sun. Since the Earth’s surface is made of very different types of land and water, it absorbs the sun’s radiant energy at different rates. Much of this energy is converted into heat as it is absorbed by land areas, bodies of water, and the air over these formations.

What is Energy?

Wind is an energy source, but what exactly is energy? Energy makes change; it does things for us. We use energy to move cars along the road and boats over the water. We use energy to bake a cake in the oven and keep ice frozen in the freezer. We need energy to light our homes and keep them at a comfortable temperature. Energy helps our bodies grow and allows our minds to think. Scientists define energy as the ability to do work.

Energy is found in different forms, such as light, heat, motion, sound, and electricity. There are many forms of energy, but they can all be put into two general categories: potential and kinetic.

Gravitational

potential energy is the energy of position or place.

A rock resting at the top of a hill contains gravitational potential energy. Hydropower, such as water in a reservoir behind a dam, is an example of gravitational potential energy.

KINETIC ENERGY

Kinetic energy is motion—the motion of waves, electrons, atoms, molecules, substances, and objects. There are several forms of kinetic energy, including: Radiant

energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays, and radio waves. Light is one type of radiant energy.

Solar energy is an example of radiant energy.

Thermal

energy, or heat, is the internal energy in substances— the vibration and movement of atoms and molecules within substances. The faster molecules and atoms vibrate and move within substances, the more energy they possess and the hotter they become. Geothermal energy is an example of thermal energy.

POTENTIAL ENERGY

Motion

energy is the movement of objects and substances from one place to another. Objects and substances move when a force is applied according to Newton’s Laws of Motion. Wind is an example of motion energy.

Chemical

energy is energy that is stored in the bonds of atoms and molecules that holds these particles together. Biomass, petroleum, natural gas, and propane are examples of stored chemical energy.

Sound

energy is the movement of energy through substances in longitudinal (compression/rarefaction) waves. Sound is produced when a force causes an object or substance to vibrate and the energy is transferred through the substance in a wave. Echoes and music are examples of sound energy.

Potential energy is stored energy and the energy of position. There are several forms of potential energy, including:

Nuclear

energy is energy stored in the nucleus of an atom. The energy can be released when the nuclei are combined (fusion) or split apart (fission). In both fission and fusion, mass is converted into energy, according to Einstein’s Theory, E = mc2.

Elastic

energy is energy stored in objects by the application of a force. Compressed springs and stretched rubber bands are examples of elastic energy.

Potential and Kinetic Energy

Electrical

energy is the movement of electrons. Lightning and electricity are examples of electrical energy.

Conservation of Energy Conservation of energy is not just saving energy. The Law of Conservation of Energy says that energy is neither created nor destroyed. When we use energy, it doesn’t disappear. We simply change it from one form of energy into another. A car engine burns gasoline, converting the chemical energy in gasoline into motion energy. Solar cells change radiant energy into electrical energy. Energy changes form, but the total amount of energy in the universe stays the same.

Energy Transformations Potential Energy

Kinetic Energy Chemical

Motion

Chemical

Motion

Radiant

Chemical

Electrical

Heat

HILL 2

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Energy Efficiency

Efficiency of a Thermal Power Plant

Energy efficiency is the amount of useful energy you get from a system compared to the energy input. A perfect, energy-efficient machine would change all the energy put in it into useful work— an impossible dream. Converting one form of energy into another form always involves a loss of usable energy, often as waste heat.

Most thermal power plants are about 35 percent efficient. Of the 100 units of energy that go into a plant, 65 units are lost as one form of energy is converted to other forms.

The remaining 35 units of energy leave the plant to do usable work.

ELECTRICITY TRANSMISSION

THERMAL ENERGY

Most energy transformations are not very efficient. The human body is a good example. Your body is like a machine, and the fuel for your machine is food. Food gives you the energy to move, breathe, and think. Your body is very inefficient at converting food into useful work. Most energy in your body is released as wasted heat.

FUEL BURNING FUEL SUPPLY

3

100 units of energy go in

TURBINE

2

5

4

FEED WATER CONDENSER

1

We use many different sources to meet our energy needs every day. They are usually classified into two groups—renewable and nonrenewable.

ELECTRICAL ENERGY

GENERATOR

BOILER

CHEMICAL ENERGY

Sources of Energy

ELECTRICITY GENERATION

STEAM LINE

MOTION ENERGY

SWITCHYARD

6

35 units of energy come out

Fuel Sources

Wind is energy in motion—kinetic energy—and it is a renewable energy source. Along with wind, renewable energy sources include biomass, geothermal energy, hydropower, and solar energy.

They are called renewable sources because they are replenished in a short time. Day after day, the sun shines, the wind blows, and the rivers flow. Renewable sources only make up about 12 percent of the United States’ energy consumption. We mainly use renewable energy sources to make electricity.

Petroleum

Coal

Natural Gas

Biomass

Uranium

How a Thermal Power Plant Works 1. Fuel is fed into a boiler, where it is burned (except for uranium which is fissioned) to release thermal energy.

2. Water is piped into the boiler and heated, turning it into steam.

3. The steam travels at high pressure through a steam line.

4. The high pressure steam turns a turbine, which spins a shaft.

In the United States, a little less than 90 percent of our energy comes from nonrenewable energy sources. Coal, petroleum, natural gas, propane, and uranium are nonrenewable energy sources. They are used to make electricity, heat our homes, move our cars, and manufacture all kinds of products. They are called nonrenewable because their supplies are limited. Petroleum, or crude oil, for example, was formed hundreds of millions of years ago from the remains of ancient sea plants and animals. We cannot make more crude oil in a short time.

5. Inside the generator, the shaft spins a ring of magnets inside coils of copper wire.

This creates an electric field, producing electricity.

6. Electricity is sent to a switchyard, where a transformer increases the voltage, allowing it to travel through the electric grid.

U.S. Consumption of Energy by Source, 2020

87.50%

Nonrenewable Sources Renewable Sources 0%

10%

12.48% 20%

30%

40%

50%

60%

70%

80%

90%

100%

PERCENTAGE OF UNITED STATES ENERGY USE

Nonrenewable Energy Sources and Percentage of Total Energy Consumption *Propane consumption is included in petroleum and natural gas figures.

PETROLEUM 34.73% Uses: transportation, manufacturing - Includes propane

NATURAL GAS 33.99% Uses: heating, manufacturing, electricity - Includes propane

COAL

Uses: electricity, manufacturing

9.89%

URANIUM

Uses: electricity

8.89%

PROPANE

1.34%

GEOTHERMAL 0.23%

Uses: heating, manufacturing

Renewable Energy Sources and Percentage of Total Energy Consumption

BIOMASS

4.88%

Uses: heating, electricity, transportation

WIND

Uses: electricity

3.24%

HYDROPOWER 2.79% Uses: electricity

SOLAR

Uses: heating, electricity

Uses: heating, electricity

Data: Energy Information Administration *Total does not add to 100% due to independent rounding.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

3

Wind Formation and Prime Locations Wind Formation

RM A

IR

Warm, Less Dense Air Cool, Dense Air

How Wind is Formed

WA

The energy in wind comes from the sun. When the sun shines, some of its radiant energy (light) reaches the Earth’s surface. Some parts of the Earth absorb more radiant energy than others. When the Earth’s surface absorbs the sun’s energy, it turns the light into thermal energy (heat). This heat on the Earth’s surface warms the air above it. The air over land usually warms faster than the air over water. As air warms, it expands. Its molecules spread farther apart. The warm air is less dense than the air around it and rises into the atmosphere. Cooler, denser air nearby flows in to take its place. This moving air is what we call wind. It is caused by the uneven heating of the Earth’s surface. Wind’s motion energy can be harvested by wind turbines to generate electricity.

CO O L A I

R

1. The sun shines on land and water.

2. Land heats up faster than water.

3. Warm air over the land rises.

4. Cool air over the water moves in.

beneath the oceans off our coasts. We also refer to the land and water off our coasts as being “offshore.”

At the edge of the ocean, where waves lap at the shoreline, is the continental shelf. It is a continuation of the North American continent we live on, and this landmass extends from the shore into the ocean as a sloping undersea plain. This undersea world is a fascinating place. The continental shelf can be as narrow as 20 kilometers (12 miles) along the west coast and as wide as 400 kilometers (249 miles) along the northeast coast of the United States. The water on the continental shelf is shallow, rarely exceeding a depth of 150 to 200 meters (490-650 feet).

The wind blows all over the planet, but certain areas have land features that can make the wind blow faster or more frequently or slower and less frequently. Some places have great variation in wind from day to night, while other areas have great seasonal variation from summer to winter. Winds can blow fast and strong across prairies or on mountains or coasts. Local winds can change direction and speed frequently if land surfaces are uneven or if forests or buildings are in their path.

Humans have been using wind energy for more than two thousand years. Early windmills were built to control flooding, pump water, grind grain, and power sawmills. Today, wind energy is mainly used to generate electricity using wind turbines. In the United States, we’ve been using modern wind turbines to generate electricity from land-based wind for several decades. Generating electricity from offshore winds in U.S. waters is in its early stages.

The first three nautical miles offshore belong to the state that it borders. According to the Outer Continental Shelf Lands Act, the Federal Government controls the area beyond that, known as the Outer Continental Shelf, or OCS. The Outer Continental Shelf consists of 1.7 billion acres of submerged lands, subsoil, and seabed in a specified zone up to 200 nautical miles from the U.S. coastline, or even farther if the continental shelf extends beyond 200 nautical miles. The OCS is divided into four regions: the Atlantic Region, the Gulf of Mexico Region, the Pacific Region, and the Alaska Region.

OUTER CONTINENTAL SHELF

PACIFIC OCS

ATLANTIC OCS

The Outer Continental Shelf (OCS) When you think of the United States, you may picture a map outlining the 50 states and their coastlines. However, the United States actually includes a huge area you cannot see, 1.7 billion acres known as the Outer Continental Shelf (OCS). This area lies

4

GULF OF MEXICO OCS ALASKA OCS

©2021 The NEED Project

PACIFIC OCS

Data: Bureau of Ocean Energy Management (BOEM)

Exploring Offshore Wind Energy

www.NEED.org

ANNUAL AVERAGE WIND SPEED

What’s a Nautical Mile?

A nautical mile is based on the circumference of the Earth.

Visualize this: cut the Earth in half at the Equator, pick up one of the halves, and turn it on its side. The Equator is the edge of the circle.

A circle is divided into 360 degrees. Each degree divides into 60 minutes. One nautical mile is one minute of arc on the planet Earth. Every country in the world uses this unit of measurement for travel in the air and on the oceans.

We are used to measuring distances in meters and feet. A nautical mile is equal to 1,852 meters, or 1.852 kilometers. In the English measurement system, a nautical mile is equal to 1.1508 miles, or 6,076 feet.

At the Equator, the Earth measures 40,075.16 km (or 24,901.55 miles). How many nautical miles is it around the Equator?

Offshore Wind Resources Air is constantly moving between land formations and water.

Because there are no obstacles to block the wind, the wind blows stronger and steadier over water than land. There is a lot of wind energy available offshore. The National Renewable Energy Laboratory estimates more than 4,000 gigawatts of wind power resources are available on the OCS — about four times the generating capacity of the U.S. electric grid today. Offshore wind resources have the potential to power a substantial portion of our nation’s energy needs.

In the U.S., wind speeds off the Pacific Coast are stronger than the Atlantic Coast or the Gulf of Mexico. Hawaii also has a lot of potential for offshore wind turbines. However, the Atlantic OCS has shallower water. Developing offshore wind farms there is the most economical option at this time due to the shallower waters and favorable ocean floor conditions.

0º 330º

30º 60º

300º

270º

90º

120º

240º 210º 180º

150º 1 nautical mile

Only about 10 percent of our wind energy resources on the OCS occur over water shallow enough for modern turbine technology.

Thus, in 90 percent of the areas offshore, the water is too deep to install a turbine with a foundation extending to the ocean floor.

Engineers have been working on and refining newer technologies, such as innovative foundations and floating wind turbines.

Image: Dominion Energy

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

5

Coastal Virginia Offshore Wind The Atlantic coast of the United States was for a long time listed as off-limits for the development of energy resources, despite several locations being perfect for wind generation. The first developments of offshore wind turbines in U.S. waters had been stalled for many years, with the first offshore turbines finally coming online in 2016 in Rhode Island waters. Virginia’s coastal waters, like New England waters, are excellent for wind development as well.

The Coastal Virginia Offshore Wind (CVOW) project has been more than a decade in the making. It is owned by Dominion Energy who has collaborated with a wide array of local organizations, officials, and communities during its development. The U.S. Bureau of Ocean Energy Management (BOEM) first held an auction for the lease of 112,799 acres located on Virginia’s OCS. The lease bid was awarded to the Virginia Electric and Power Company (Dominion) in 2013. Subsequently, Dominion Energy installed the first two utility scale turbines in U.S. Federal waters - only the second offshore wind installation in the U.S. These research turbines came online in October of 2020 and were installed approximately 27 miles off the coast of Virginia Beach. The pair of turbines generates 12 Megawatts (MW) of electricity and has proven this area to be a good fit for a larger wind farm in the Atlantic Ocean.

Dominion is working to install a much larger wind farm in the same area. The CVOW project is set to begin construction in 2024, and will include 176 turbines, each standing over 800 feet tall. Once fully completed in 2026, the wind farm is expected to generate over 2,600 MW, enough to power up to 660,000 homes during times of peak demand. Due to the curvature of the Earth, it will be difficult to see the turbines from shore. You will likely need to take a boat out to see them or fly over the area to get an up-close look at them, and they have been planned to minimize impacts on ship traffic, fishing, and whale migration. In order to protect the North Atlantic right whale, foundation installation is limited to only certain times of year when they are not in the area. Additionally, to minimize the impact to sensitive species including the right whale, bubble curtains will be used during turbine installation to form a barrier that will help to block or lessen the sound of this construction activity under water.

Observers will also be posted near the construction activities to look for protected species, including whales, in the area. If these species are located within the exclusion zone, work will be stopped, if it is safe to do so, until the area is clear.

The turbines will be arranged in a grid-like pattern, with the turbines far enough away from each other that they can rotate with the wind and not disturb the wind reaching nearby turbines. The CVOW project will require several hundred miles of buried, underwater cables to connect the turbines and deliver electricity to the shore.

The project will also have up to three offshore substations that will step up the voltage to deliver the electricity onshore efficiently.

The CVOW project’s cables will bring the electricity onshore at the State Military Reservation. From there, transmission lines will then transport the electricity to a switching station at U.S. Naval Air Station Oceana where the transmission lines will transition from underground to overhead and then carry the electricity to Dominion Energy’s Fentress Substation to deliver to customers on the grid.

CVOW will help the Commonwealth achieve the goals of the Virginia Clean Economy Act, by shifting away from generation facilities that use combustion and produce carbon dioxide as a by-product. The CVOW project will help Virginia to avoid as much as five million tons of CO2 emissions annually from clean, reliable offshore wind.

CVOW LEASE AREA

Image: Bureau of Ocean Energy Management (BOEM)

From Offshore to Onshore

6

Schematic courtesy of Dominion Energy

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Physics of Wind Wind Speed and Direction

Turbine Geometry

WIND DIRECTION

A weather vane, or wind vane, is used to show the direction of the wind. A wind vane points toward the source of the wind. Some locations such as airports use windsocks to show the direction in which the wind is blowing.

Wind direction is reported as the direction from which the wind blows, not the direction toward which the wind moves. A north wind blows from the north toward the south.

Swept area of blades

Rotor Diameter

Radius ROTOR BLADE

WIND VELOCITY

Wind speed is important because the amount of electricity that wind turbines can generate is determined in large part by wind speed, or velocity.

Hub Height

A doubling of wind velocity from the low range into the optimal range of a turbine can result in eight times the amount of power produced. This huge difference helps wind energy companies decide where to site wind turbines.

Wind power, measured in watts, is determined by air density, the area swept by the turbine blades, and wind velocity, according to the following formula:

THE POWER OF WIND

P=½ρAV³

P = power in watts ρ = The air density (1.2kg/m³ @ sea level and 20° C) A = The swept area of the turbine blades (m² square meters) V = wind speed (meters per second)

The potential energy produced from wind is directly proportional to the cube of the wind speed. As a result, increased wind speeds of only a few miles per hour can produce a significantly larger amount of electricity. For instance, a turbine at a site with an average wind speed of 16 mph would produce 50 percent more electricity than at a site with the same turbine and average wind speeds of 14 mph. Choosing where to site a wind farm is an important part of the process.

TOWER

When wind moves across the Earth’s surface, it is slowed by friction as it runs into and flows around obstacles on the surface or meets other air masses. Friction also affects the direction of the wind.

Higher in the atmosphere, away from the Earth, the wind meets fewer obstacles, and therefore less friction is produced. Winds there are smooth and fast.

Wind shear is defined as a change in wind speed and/or wind direction at different heights in the atmosphere or within a short distance. It can be in a horizontal direction, a vertical direction, or in both directions. Some wind shear is common in the atmosphere.

Larger values of wind shear exist near fronts, cyclones, and jet streams. Wind shear in an unstable atmospheric layer can result in turbulence.

WIND VANE

ANEMOMETER

Wind speed can be measured using an instrument called an anemometer. One type of anemometer is a device with three arms that spin on top of a shaft.

Each arm has a cup on its end. The cups catch the wind and spin the shaft. The harder the wind blows, the faster the shaft spins. A device inside counts the number of rotations per minute and converts that figure into miles per hour (mph) or meters per second (m/s). A display on a recording device called a data logger shows the speed of the wind. There are also digital anemometers that measure wind speed.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

7

WIND DIRECTION

Onshore Wind Turbine Diagram Blade

Rotor Hub

Low-speed shaft Low-sp Gear box

Bla de

High-speed shaft

Nacelle Tower

Wind direction is reported as the direction from which the wind blows, not the direction toward which the wind moves.

Turbulence is defined as a variation in the speed and direction of the wind in very short time periods (1 second) that results in random, disordered movement of air molecules. It occurs when the flow of wind is disturbed, and the direction or speed is changed. When wind mixes warm and cold air together in the atmosphere, turbulence is also created. This turbulence is sometimes felt as a bumpy ride during an airplane flight.

Wind shear and turbulence are important factors for wind turbine engineers to study because they can affect the operation and output of turbines, and even cause them to fail. Studying the wind shear and turbulence in an area often tells engineers more about how high to place the tower of a turbine to get the best wind conditions.

Modern Wind Machines Today, wind is harnessed and converted into electricity using machines called wind turbines. The amount of electricity that a turbine produces depends on its size and speed of the wind. Most large wind turbines have the same basic parts: blades, a tower, and a gear box. However, some wind turbine designs involve slightly different configurations, or even operate without the gear boxes.

Generally speaking, most turbines on land work the same way. Their parts work together to convert the wind’s kinetic energy into motion energy that generates electricity. The process works like this:

Generator Gene Ge neraato t r

Wind turbines are most efficient when they are built in an area where winds blow consistently at a minimum of 6-16 miles per hour (2.77 meters per second). Faster winds generate more electricity. High above ground, winds are stronger and steadier.

There are many different types of wind turbines with different tower and hub heights, as well as varying blade designs and lengths. Wind turbines can be designed to optimize output for specific ranges of wind speed. Turbines typically can generate electricity when winds are between 6 and 55 mph (3-25 m/s). They operate most efficiently, however, when wind speeds fall between 18-31 mph (8-14 m/s).

Wind turbines also come in different sizes, based on the amount of electric power they can generate. Small turbines may produce only enough electricity to power a few appliances in one home. Large turbines are often called utility-scale because they generate enough power for utilities, or electric companies, to sell. Most utility-scale turbines installed in the U.S. produce one to three megawatts of electricity, enough to power 300 to 900 homes. Large turbines are grouped together into wind farms, which provide bulk power to the electric grid.

1. The moving air is caught by the blades and spins the rotor.

2. The rotor is connected to a low-speed shaft. When the rotor spins, the shaft turns.

3. The low-speed shaft is connected to a gear box. Inside the gear box, a large slow-moving gear turns a small gear quickly.

4. The small gear turns another shaft at high speed.

5. The high-speed shaft is connected to a generator. As the highspeed shaft turns the generator, it produces electricity.

6. The electric current is sent through cables down the turbine tower to a transformer that changes the voltage of the current before it is sent out on transmission lines.

8

Deepwater Wind, Rhode Island

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Aerodynamics of Wind Turbine Blades Why Turbine Blades Move

Understanding Wind

There are two important reasons why wind turbine blades are able to spin in the wind: Newton’s Third Law and the Bernoulli Effect.

Wind turbine blades must be optimized to efficiently convert oncoming winds into motion energy to rotate the main driveshaft.

But when designing turbine blades, the real wind is only one part of a larger equation. Good blades must also account for the apparent wind that is experienced as the blade passes through the air.

Newton’s Third Law states that for every action, there is an equal and opposite reaction. In the case of a wind turbine blade, the action of the wind pushing air against the blade causes the reaction of the blade being deflected, or pushed. If the blade has no pitch (or angle), the blade will simply be pushed backwards (downhill). But since wind turbine blades are set at an angle, the wind is deflected at an opposite angle, pushing the blades away from the deflected wind. This phenomenon can be viewed on a simple, flat blade set at an angle. If you push the blade with your finger from the direction of the oncoming wind, the blade will deflect away from your finger.

Bernoulli’s Principle, or the Bernoulli Effect, tells us that faster moving air has lower pressure. Wind turbine blades are shaped so that the air molecules moving around the blade travel faster on the downwind side of the blade than those moving across the upwind side of the blade. This shape, known as an airfoil, is like an uneven teardrop. The downwind side of the blade has a large curve, while the upwind side is relatively flat. Since the air is moving faster on the curved, downwind side of the blade, there is low pressure on this side of the blade. This difference in pressure on the opposite sides of the blade causes the blade to be “lifted” towards the curve of the airfoil.

Imagine riding your bike on a day with a fresh breeze at your side.

As you begin to ride and pick up speed, you feel this wind from the side, but also wind pushing back at you from the direction you are moving. When you stop riding, there is just the wind from the side again. This wind that is “created” as you are moving is known as headwind. The headwind, combined with the real wind, is known as apparent wind. A wind turbine blade experiences apparent wind as it passes through the air. This apparent wind is from a different direction than the “real” wind that has caused the blade to begin moving. Since the tips of large turbine blades may be moving through the air at speeds up to 322 km/h (200 mph), this apparent wind can be very significant!

APPARENT WIND

(A)

REAL WIND (R) + HEADWIND (H) = APPARENT WIND (A)

AIRFOIL SHAPE: A CROSS-SECTION

(H) (A) Faster air

(R)

Aerodynamics Slower air

Efficient blades are a key part of generating power from a wind turbine. The efficiency of a wind turbine blade depends on the drag, lift, and torque produced by the blade. These factors are affected by the size and shape of the blades, the number of blades, and the blade pitch.

Drag

Text and graphics adapted and used with permission from KidWind Project, Inc. For more information related to this topic, visit http://learn.kidwind.org. ©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Drag is defined as the force on an object that resists its motion through a fluid. When the fluid is a gas such as air, the force is called aerodynamic drag, or air resistance. Drag is a force that is working against the blades, causing them to slow down. Drag is always important when an object moves rapidly through the air or water.

Airplanes, race cars, rockets, submarines, and wind turbine blades are all designed to have as little drag as possible.

9

Imagine riding your bike down a big hill. To go faster, you might tuck your body to expose as little of it to the apparent wind as possible.

This is a trick to reduce drag. Now imagine you have a big parachute strapped to your back when you ride down the hill. The parachute increases the drag significantly and this drag force slows you down.

Drag increases with the area facing the wind. A large truck has a lot more drag than a motorcycle moving at the same speed. Wind turbine blades have to be streamlined so they can efficiently pass through the air. Changing the angle of the blades will change the area facing the apparent wind. This is why blade pitch angles of 1020 degrees tend to have much less drag than greater angles.

Drag also increases with wind speed. The faster an object moves through the air, the more drag it experiences. This is especially important for wind turbine blades, since the blade tips are moving through the air much faster than the base of the blade. The shape and angle of wind turbine blades changes along the length of the blade to reduce drag at the blade tips.

Reducing Drag on Wind Turbine Blades:

Speed Remember that the speed of air passing around the blade is a combination of the real wind and the headwind as the blade moves. The faster the blade is moving, the more drag/headwind it experiences, but the lift force will also increase as the blades move faster.

The tips of wind turbine blades travel much further with each rotation of the blades, and therefore move through the air much faster than the roots of the blades. Since they are traveling the furthest distance with each rotation (distance/time = speed), the tips of turbine blades experience more headwind. The roots, or base, of the blades do not experience as much headwind since they are passing through the air much more slowly.

The faster the air molecules are passing over a blade or wing, the more lift can be generated. So the tips of real turbine blades generate much more lift than the roots. Some large wind turbines have blade tip speeds over 322 km/h (200 mph).

LIFT

1. Change the pitch—the angle of the blades dramatically affects the amount of drag.

2. Use fewer blades—each blade is affected by drag.

3. Use light-weight materials—reduce the mass of the blades by using less material or lighter material.

4. Use smooth surfaces—rough surfaces, especially on the edges, can increase drag.

5. Optimize blade shape—the tip of a blade moves faster than the base. Wide, heavy tips increase drag.

Lift Lift is the aerodynamic force that allows airplanes and helicopters to fly. The same force applies to the blades of wind turbines as they rotate through the air. Lift opposes the force of drag, helping a turbine blade pass efficiently through air molecules. The main goal of a well-designed wind turbine blade is to generate as much lift as possible while minimizing drag.

AIRFOIL SHAPES

The amount of lift a blade or wing can generate is determined by several factors—the shape of the blade, the speed of the air passing around the blade, and the angle of the blade relative to the apparent wind.

Shape The airfoil shape of the blade helps to generate lift by taking advantage of the Bernoulli Effect. Wind turbine blade designers have experimented with many different airfoil shapes over the years in an effort to find the perfect shape that will perform well in a range of wind speeds. Even minor changes in this blade shape can dramatically affect the power output and noise produced by a wind turbine.

The airfoil profile (shape) of a turbine blade will actually change as you move down the length of the blade, generally getting flatter and narrower toward the tips of the blades. This is to optimize the lift and minimize drag.

10

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

BLADE PITCH

Angle The angle or pitch of the blades also greatly impacts how much lift is generated. On large wind turbines, the blade angle is constantly adjusted to give the blades the optimal angle into the apparent wind. The angle of the blade relative to the plane of rotation is known as the pitch angle. The angle of the blade relative to the apparent wind is called the angle of attack. The angle of attack is very important, but also complicated since it will change as the real wind speed changes and the speed of the blade (headwind) changes. On most airfoil blade shapes, an angle of attack of 10-15 degrees creates the most lift with the least drag.

Real wind turbine blades typically have a twisted pitch — meaning the blade angle is steeper at the root of the blade and flatter further away from the hub. Once again, this is due to the fact that the tips move so much faster through the air. By twisting the pitch, the blades are able to take advantage of a more ideal angle of attack down the length of each blade. The tips of a real turbine blade may have close to a 0 degree pitch angle, but this section of the blade generates a great deal of lift.

Torque Torque is a force that turns or rotates something. When you use a wrench on a bolt or twist a screw loose with a screwdriver, you are generating torque. Torque is a lot like leverage. If you are trying to turn a wrench, sometimes you need a lot of leverage to loosen a tight bolt. Wind turbine blades are like big levers, but instead of your muscle turning them they use the force of the wind.

LOWER PITCH NEAR TIP 0°

5° HIGHER PITCH NEAR ROOT

10°

15°

REAR VIEW OF BLADE PITCH AT HUB

Torque is equal to the force multiplied by distance. This means that the longer your blades are, the more torque you can generate. For example, imagine someone trying to loosen a tight bolt. Pushing with all their might, they can exert 100 pounds of force. If their wrench was 1 foot long, they would be exerting 100 foot-pounds of torque. If they applied the same force to a 2 foot long wrench, they would be exerting 200 foot-pounds of torque on the bolt. This additional leverage makes it much easier to loosen the bolt.

Image: Dominion Energy

TORQUE

LESS TORQUE

Text and graphics adapted and used with permission from KidWind Project, Inc. For more information related to this topic, visit http://learn.kidwind.org.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

MORE TORQUE 11

Gearing Up For More Power On a real wind turbine, the long blades give the turbine a lot of leverage to provide power to the generator. Utility scale large turbines often have large gear boxes that increase the revolutions per minute of the rotor by 80 or 100 times. This big gear reduction demands a lot of leverage from the blades. Think about riding your bicycle—when you shift into high gear it may be harder to pedal. A higher gear demands more torque.

Power output is directly related to the speed of the spinning drive shaft (revolutions per minute or rpm) and how forcefully it turns.

A large wind turbine has a rotor with blades, a gear box, and a generator. As the blades spin, the rotor rotates slowly with heavy torque. The generator has to spin much faster to generate power, but it cannot use all the turning force, or torque, that is on the main shaft. This is why a large wind turbine has a gear box.

MORE TORQUE

LESS TORQUE

Inside the gear box, there is at least one pair of gears, one large and one small. The large gear, attached to the main shaft, rotates at about 20 revolutions per minute with a lot of torque. This large gear spins a smaller gear, with less torque, at about 1,500 revolutions per minute. The small gear is attached to a small shaft that spins the generator at high speed, generating power. The relationship between the large and small gears is called the gear ratio. The gear ratio between a 1,500 rpm gear and a 20 rpm gear is 75:1.

Putting It All Together Increasing the torque generated by the blades often increases the drag they experience as they rotate. For example, longer blades will generate more torque and more drag. Increasing the blade pitch will generally increase the torque and increase the drag. Increasing the number of blades will generally give you more torque and more drag. For this reason, it is important to design blades to match the load application. If you are using a windmill to lift a bucket of weights, a slowly spinning rotor that generates lots of torque will be best. If you are using a turbine to light a string of LED bulbs wired in series, you will need a rotor that spins very rapidly with very little drag.

MORE DRAG

LESS DRAG

Wind Turbine Efficiency—Betz Limit Wind turbines must convert as much of the available wind energy into electricity as possible to be efficient and economical.

As turbines capture energy from the wind, the resultant wind has less energy and moves more slowly. If the blades were 100 percent efficient, they would extract all of the wind’s energy and the wind would be stopped. The maximum theoretical percentage of wind that can be captured has been calculated to be about 59 percent. This value is called the Betz Limit and modern turbines are designed to approach that efficiency. Most turbines today reach efficiencies of 25-45 percent.

12

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Electricity Electricity is different from primary energy sources like petroleum or wind—it is a secondary energy source. That means we must use another energy source to produce electricity. Electricity is sometimes called an energy carrier because it is an efficient and safe way to move energy from one place to another, and it can be used for so many tasks. Since electricity is used for many tasks in our daily lives, it is needed and produced in large quantities each day.

A Mysterious Force What exactly is the mysterious force we call electricity? It is moving electrons. And what are electrons? They are tiny particles found in atoms. Everything in the universe is made of atoms—every star, every tree, every animal. The human body is made of atoms. Air and water are, too. Atoms are the building blocks of the universe. Atoms are so small that millions of them would fit on the head of a pin.

Atomic Structure

Atom PROTON NUCLEUS

NEUTRON

ELECTRON

Atoms are made of smaller particles. The center of an atom is called the nucleus. It is made of particles called protons, which carry a positive (+) charge, and neutrons, which carry no charge. Protons and neutrons are approximately the same size. The mass of a single proton is 1.67 x 10-24 gram. Nuclear energy is contained within the nucleus, because a strong nuclear force holds the protons and neutrons together.

Protons and neutrons are very small, but electrons are much smaller—1,835 times smaller, to be precise. Electrons carry a negative (-) charge and move around the nucleus in orbits a relatively great distance from the nucleus. If the nucleus were the size of a tennis ball, the diameter of the atom with its electrons would be several kilometers.

If you could see an atom, it might look a little like a tiny center of spheres surrounded by giant invisible clouds (or energy levels).

Electrons are found in these energy levels and are held there by an electrical force. The protons and electrons of an atom are attracted to each other. They both carry an electrical charge. The positive charge of the protons is equal to the negative charge of the electrons. Opposite charges attract each other.

Carbon Atom Carbon Atom A carbon atom has six protons and six neutrons in the nucleus, two electrons in the inner energy level, and four electrons in the outer energy level.

OUTER INNE

ENERGY LEV

EL

R ENERGY LEVE

L

NUCLEUS PROTONS (+)

NEUTRONS

When an atom is in balance, it has an equal number of protons and electrons. The number of neutrons can vary.

ELECTRONS (–)

Elements An element is a substance in which all of the atoms have the same number of protons. The number of protons is given by an element’s atomic number, which identifies elements. A stable atom of hydrogen, for example, has one proton and one electron, with almost always no neutrons. A stable atom of carbon has six protons, six electrons, and typically six neutrons. The atomic mass of an element is the combined mass of all the particles in one atom of the element.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

13

Electrons The electrons usually remain a constant distance from the nucleus in energy levels. The level closest to the nucleus can hold two electrons. The next level can hold up to eight. Additional levels can hold more than eight electrons.

The electrons in the levels closest to the nucleus have a strong force of attraction to the protons. Sometimes, the electrons in the outermost level—the valence energy level—do not. In this case, these electrons— valence electrons—easily leave their energy levels. Other times, there is a strong attraction between valence electrons and the protons. Often, extra electrons from outside the atom are attracted and enter the valence energy level. When the arrangement of electrons changes in these ways, energy is gained or transformed. We call this energy from electrons electrical energy.

Applying a force can make the electrons move from one atom to another.

Electrical Energy The positive and negative charges within atoms and matter usually arrange themselves so that there is a neutral balance.

However, sometimes there can be a buildup of charges creating more negative than positive charges, or more positive charges than negative charges. This imbalance produces an electric charge. Unlike electric current where electrons are moving, these electrons don’t move until there is another object for them to move to. This is called static electricity. When the charges become too unbalanced there is a discharge of electrical energy between positively and negatively charged areas. This is what causes lightning to jump from cloud to cloud, or between a cloud and the ground.

Bar Magnet

Like Poles Like poles of magnets (N-N or S-S) repel each other.

Opposite Poles Opposite poles of magnets (N-S) attract each other.

Magnets In most objects, the molecules that make up the substance have atoms with electrons that spin in random directions. They are scattered evenly throughout the object. Magnets are different— they are made of atoms that have north- and south-seeking poles.

The atoms in a magnet are arranged so that most of the northseeking poles point in one direction and most of the south-seeking poles point in the other.

Spinning electrons create small magnetic fields and act like microscopic magnets or micro-magnets. In most objects, the electrons located around the nucleus of the atoms spin in random directions throughout the object. This means the micro-magnets all point in random directions cancelling out their magnetic fields. Magnets are different—most of the atoms’ electrons spin in the same direction, which means the north- and south-seeking poles of the micro-magnets they create are aligned. Each micromagnet works together to give the magnet itself a north- and south-seeking pole.

14

A magnetic field can produce electricity. In fact, magnetism and electricity are really two inseparable aspects of one phenomenon called electromagnetism. A changing magnetic field can produce electricity. Every time there is a change in an electric field, a magnetic field is produced. This relationship is used to produce electricity. Some metals, such as copper, have electrons that are loosely held. They can be pushed from their valence energy levels by the application of a magnetic field. If a coil of copper wire is moved around a changing magnetic field, or if magnets are moved around a coil of copper wire, an electric current is generated in the wire.

Electric current can also be used to produce magnets. Around every current-carrying wire is a magnetic field, created by the uniform motion of electrons in the wire. Magnets used to produce electric current are called electromagnets.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Generating Electricity When it comes to the production of electricity, it’s all turbines and generators. A turbine is a device that converts the flow of a medium such as air, steam, or water into motion energy to power a generator. A generator is an engine that converts motion energy into electrical energy using electromagnetism.

An electric generator is actually an electric motor that runs backward. Work is done to cause magnets to spin within coils of wire to produce electricity. Depending on the generator’s design, work can also cause the wires to move. When the wire moves through the external magnetic field, electrons in the wire are pulled and move through the wire. These electrons can be directed out of the generator as electricity.

Although electric motors and generators may seem complicated, the principle of electromagnetism is simple. When electricity moves through a wire, a magnetic field is created around the wire.

In an electric motor, the motor’s wire is placed between external magnets. When electricity is sent through the wire, the magnetic field created around the wire interacts with the magnetic field of the external magnets. This interaction causes the wire to move. If the wire is designed so it is free to turn, the wire will spin and you have an electric motor.

Power plants use huge turbine generators to generate the electricity we use in our homes and businesses. Power plants can use many fuels to spin turbines. Coal, oil, biomass, and natural gas are burned to create steam to turn turbines. Nuclear power plants create steam from splitting atoms. Geothermal power plants harness steam from high pressure vents at the surface. Wind turbines, however, use already moving air and do not require heat.

Once the electricity is produced, it is moved to our homes and businesses. On land and under water, it moves through large electrical lines. Electricity moves most efficiently under high voltage. When the electricity leaves a power plant, its voltage must be drastically increased. When it reaches our homes and businesses, the voltage must be reduced so it will not burn or damage things that use electricity. The voltage of electricity is

easily increased or decreased by a transformer. Transformers are commonly seen in our neighborhoods. Electrical substations are a series of transformers used to increase or decrease voltage. If you have an overhead electrical line that goes into your house, you will see a transformer on the pole where the overhead line leaves the larger power line. Usually, these overhead transformers are grey cylinders. They reduce the voltage so that the electricity can safely enter your house.

The Grid Once electricity is produced, it is distributed to consumers through the electric grid. The grid consists of power generators, powerlines that transmit electricity, and the components that make it all work, including substations, meters, homes, and businesses.

In the United States, there are over 160,000 miles of high-voltage electric transmission lines. They take electricity produced at power plants to transformers that step up the voltage so that it can travel more efficiently along the grid. Before entering your home, another transformer steps down the voltage so that it can be used to operate your lights, appliances, and other electrical needs.

One challenge facing renewable energy sources, including wind, is that the most efficient spots for producing electricity are often in secluded or rural areas, like offshore. Most traditional power plants are built near population centers and the fuel source is transported to the plant. This allows the electricity produced to be quickly and economically transmitted to consumers. In order to distribute the energy produced from some renewable sources, the electricity must travel farther distances. The longer the electricity has to travel the more transmission lines are needed and the more energy is lost (as heat) along the way.

To overcome the challenge of distributing electricity quickly and efficiently, not only for renewable energy sources, but also for nonrenewable sources, steps are being taken to upgrade the U.S. electricity grid to a “smart grid.” Using new technology the smart grid will help to save money, operate reliably, reduce its impact on the environment, and handle the growing power needs of today and tomorrow.

Transporting Electricity Transmission lines carry electricity long distances

Wind Turbine

Transformer in offshore substation steps up voltage for transmission

Transmission lines carry electricity long distances under water to land

Onshore substation with transformers to adjust voltage for further transmission

Power Tower

Distribution lines carry electricity to houses

Step-down transformer reduces voltage (substation)

Electric Poles

Neighborhood transformer on pole steps down voltage before entering house

*Graphic not to scale

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

15

High-Voltage Transmission Lines The Continental U.S. Electric Grid

Current

The flow of electrons can be compared to the flow of water. The water current is the number of molecules of water flowing past a fixed point; electric current (I) is the number of electrons flowing past a fixed point.

With electricity, conducting wires take the place of the pipe. As the cross-sectional area of the wire increases, so does the amount of electric current (number of electrons) that can flow through it.

Current is measured in amperes (A).

Resistance

DATA: FEDERAL EMERGENCY MANAGEMENT AGENCY

Measuring Electricity We are familiar with terms such as watt, volt, and amp, but we do not always have a clear understanding of these terms. We buy a 13watt light bulb, a tool that requires 120 volts, or an appliance that uses 8.8 amps, but we don’t think about what those units mean.

Using the flow of water as an analogy can make electricity easier to understand. The flow of electrons in a circuit is similar to water flowing through a hose. If you could look into a hose at a given point, you would see a certain amount of water passing that point each second.

The amount of water depends on how much pressure is being applied—how hard the water is being pushed. It also depends on the diameter of the hose. The harder the pressure and the larger the diameter of the hose, the more water passes each second. The flow of electrons through a wire depends on the pressure pushing the electrons and on the cross-sectional area of the wire.

Resistance (R) is a force that opposes the movement of electrons, slowing their flow. Using the water analogy, resistance is anything that slows water flow, such as a smaller pipe or fins on the inside of a pipe. In electrical terms, the resistance of a conducting wire depends on the properties of the metal used to make the wire and the wire’s diameter. Copper, aluminum, and silver—metals used in conducting wires—have different resistance.

Resistance is measured in units called ohms (Ω). There are devices called resistors, with set resistances, that can be placed in circuits to reduce or control the current flow. Any device placed in a circuit to do work is called a load. The light bulb in a flashlight is a load. A television plugged into a wall outlet is also a load. Every load has resistance.

Voltage Voltage Water Tank

Voltage

The force or pressure that pushes electrons in a circuit is called voltage. Using the water analogy, if a tank of water were suspended one meter above the ground with a one-centimeter pipe coming out of the bottom, the water pressure would be similar to the force of a shower. If the same water tank were suspended 10 meters above the ground, the force of the water would be much greater, possibly enough to hurt you.

Voltage (V) is a measure of the pressure applied to electrons to make them move. It is a measure of the strength of the current in a circuit and is measured in volts (V). Just as the 10-meter tank applies greater pressure than the one-meter tank, a 10-volt power supply (such as a battery) would apply greater pressure than a one volt power supply.

10 m

Water Tank 1m

Current

AA batteries are 1.5 volt; they apply a small amount of voltage for lighting small flashlight bulbs.

A car usually has a 12-volt battery—it applies more voltage to push current through circuits to operate the radio or defroster.

The standard voltage of wall outlets is 120 volts—a dangerous voltage. An electric clothes dryer is usually wired at 240 volts—a very dangerous voltage.

16

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Resistance Resistance

Ohm’s Law VOLTAGE = CURRENT X RESISTANCE V=IxR

Water Tank

Water Tank

or

V=AxΩ

CURRENT = VOLTAGE / RESISTANCE I=V/R

or

A=V/Ω

RESISTANCE = VOLTAGE / CURRENT R=V/I

or

Ω=V/A

Formulas for Measuring Electricity The formula pie works for any three variable equation. Put your finger on the variable you want to solve for and the operation you need is revealed.

No Resistance

Resistance

Ohm’s Law

The relationship between voltage, current, and resistance is defined in Ohm’s Law. George Ohm, a German physicist, discovered that in many materials, especially metals, the current is proportional to the voltage. He found that if he doubled the voltage, the current also doubled. If he reduced the voltage by half, the current dropped by half. The resistance of the material remained the same. This relationship is called Ohm’s Law and can be described using the formula to the right.

Electric Power

Power (P) is a measure of the rate of doing work or the rate at which energy is converted. Electric power is the rate at which electricity is produced or consumed. Using the water analogy, electric power is the combination of the water pressure (voltage) and the rate of flow (current) that results in the ability to do work.

A large pipe carries more water (current) than a small pipe. Water at a height of 10 meters has much greater force (voltage) than at a height of one meter. The power of water flowing through a one centimeter pipe from a height of one meter is much less than water through a 10-centimeter pipe from 10 meters.

Electric power is defined as the amount of electric current flowing due to an applied voltage. It is the amount of electricity required to start or operate a load for one second. Electric power is measured in watts (W).

Electrical Energy Electrical energy introduces the concept of time to electric power.

In the water analogy, it would be the amount of water falling through the pipe over a period of time. When we talk about using power over time, we are talking about using energy. Using our water example, we could look at how much work could be done by the water in the time that it takes for the tank to empty.

The electrical energy that a device consumes can be determined if you know how long (time) it consumes electric power at a specific rate (power). To find the amount of energy consumed, you multiply ©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

V=IxR I = V/R R = V/I

the rate of energy consumption (watts) by the amount of time (hours) that it is being consumed. Electrical energy is measured in watt-hours (Wh). energy (E) = power (P) x time (t) E = P x t or E = W x h = Wh Another way to think about power and energy is with an analogy to traveling. If a person travels in a car at a rate of 40 miles per hour (mph), to find the total distance traveled, one would multiply the rate of travel by the amount of time traveled at that rate. If a car travels for one hour at 40 miles per hour, it would travel 40 miles. distance = 40 mph x 1 hour = 40 miles If a car travels for three hours at 40 miles per hour, it would travel 120 miles. distance = 40 mph x 3 hours = 120 miles The distance traveled represents the work done by the car. When we look at power, we are talking about the rate that electrical energy is being produced or consumed. Energy is analogous to the distance traveled or the work done by the car.

A person wouldn’t say they took a 40-mile per hour trip because that is the rate. The person would say they took a 40-mile trip.

We would describe the trip in terms of distance traveled, not rate traveled. The distance represents the amount of work done. The same applies with electrical energy. You would not say you used 100 watts of light energy to read a book, because a watt represents the rate you use energy, not the total energy used. The amount of energy used would be calculated by multiplying the rate by the amount of time you read.

17

Offshore Wind Turbine Technology and Placement

Many turbines on land use a gearbox-driven design, where the gearbox speeds up the shaft to a higher speed for generation.

Offshore turbines installed today utilize a different design called a direct drive. In direct drive turbines, the rotor shaft spins the generator directly at the same speed as the blades and does not utilize a gearbox. Gearboxes have many moving parts, require lubrications and fluids monitoring, and thus, require regular maintenance to ensure reliability. For offshore, where access to maintain the turbines can be a bigger challenge, direct drive designs are more reliable and require less maintenance than gearbox-driven turbines.

Direct Drive Wind Turbine Diagram Generator

Bl Blade Rotor Hub

Nacelle Tower

Offshore Wind Turbine Max Height:

To minimize maintenance costs, turbines and towers are coated with high grade exterior paint. They are typically painted light grey or off-white to help them blend into the sky, reducing visual

18

~800ft to 900ft

Swept Area: 1.3 million ft

3

Blade Rotor Hub

Direct drive turbine designs require a larger generator to produce enough power, since the generator speed is equivalent to the rotor speed. In order to make these generators achieve higher output, permanent magnetic poles are used instead of coils of wire in the generator. The magnets used in the design of the generator require a configuration that makes the direct drive model more efficient, but it does require that the generator is a different shape than those used in conventional turbines. The generator itself is often larger than those in a gear-driven model but can still be housed within the nacelle. Despite the larger generator, a direct drive model is also often lighter than conventional models, as it doesn’t require the gearbox and extra shaft length.

The nacelle is a rectangular box that encloses the generator, hub, and electronic components. It is specially designed to protect the machinery and electronics inside from corrosive sea water.

The nacelle may have its own heating and cooling system, which maintains the temperature inside the nacelle. There may be an automatic greasing system to lubricate bearings and blades. Wind sensors on the turbine are connected to a system that always keeps the nacelle facing into the wind, maximizing the amount of electricity produced.

Bla de

de

Building commercial-scale offshore wind farms depends on sitespecific conditions, such as water depth, geology of the seabed, and wave attributes. In shallow water four to thirty meters (13-100 feet) deep, a large steel tube called a monopile is used as one type of foundation. A monopile may be six meters (20 feet) across and may include a variation in structure that involves support posts. The monopile is driven into the seabed 24 to 30 meters (78-100 feet) below the mud line. The monopile or other foundation structure supports the tower and nacelle. Offshore turbine foundations must be designed to withstand the harsh environment of the ocean, including storm waves, hurricane-force winds, and even ice flows.

In very deep waters, a floating structure may be used instead of a fixed monopile.

Bla

Offshore Wind Turbine Technology

Nacelle Blade Length: 354ft

Tower

Rotor Diameter: 728ft

Transition Piece

Tower:

*452ft to 492ft

Service operation vessel

Autonomous Underwater Vehicle (AUV)

Foundation Water Depth: 80ft - 150ft+

Electricity Cables

Generation Capacity: 14MW

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

impacts from the shore. Lower sections of the support towers may be painted bright colors to increase navigational safety for passing vessels. Offshore turbines also include navigation and aviation warning lights.

To take advantage of the steadier winds, offshore turbines are bigger than onshore turbines and have an increased generation capacity.

Offshore turbines installed in global waters today generally have nameplate capacities between 2 megawatts (MW) up to as high as 9 MW, with tower heights greater than 61 meters (200 feet) and rotor diameters of 76 meters (250 feet) or more. Future models, like those planned for CVOW, will be rated at even higher capacities, (12-15MW), with even larger dimensions. The maximum height of the structure, at the very tips of the blades, can easily exeed 240 meters (800 feet) or more.

Floating Offshore Wind Turbines When water is too deep for a monopile foundation to be practical, a floating turbine is necessary. From the tower up, the floating turbine is the same as an anchored turbine, with its tower, nacelle, hub, and blades. But under the tower, the foundation is very different.

The supporting structure of a floating turbine can take many shapes, but the key component is a floating foundation that is tethered to anchors on the sea floor with mooring lines.

Offshore Wind Development The first offshore wind project was installed off the coast of Denmark in 1991. Since that time, commercial-scale offshore wind facilities have been operating in shallow waters around the world. Europe currently leads the offshore wind farm industry with over 1,900 turbines installed and grid connected in Great Britain, Denmark, Germany, Belgium, the Netherlands, Sweden, Finland, Norway, and Ireland. Other areas of the world rely on offshore wind power, too, including China and Japan. The largest offshore wind farm in the world is the London Array in the United Kingdom, with 175 turbines and 630 MW of capacity.

The first offshore wind farm in the United States, the Ørsted Deepwater Wind project, southeast of Block Island in Rhode Island, began construction in 2015 and was completed in 2016. The five turbine, 30 MW wind farm was brought online late in 2016, and has the ability to power roughly 17,000 homes per year, reducing the reliance on diesel-fired electricity generation and improving air quality for residents.

The CVOW Project will begin construction in 2024. The wind farm will consist of up to 180 turbines that can provide over 2,600 MW of power to 660,000 homes in Virginia. It will be the largest offshore wind installation in the U.S., and will help to offset as much as five million tons of CO2 emissions annually.

Generating and Transporting Electricity Wind turbines work by slowing down the speed of the wind. All wind turbines operate in the same basic manner. As the wind blows, it flows over the airfoil-shaped blades of the wind turbine, causing the turbine blades to spin. The blades are connected to a shaft that turns an electric generator to produce electricity. The newest wind turbines are highly technologically advanced, and include a number of engineering and mechanical innovations to help maximize efficiency and increase the production of electricity.

Electricity generated by offshore wind turbines needs to be transmitted to shore and connected to the power grid. Offshore, each turbine is connected to an electric service platform (ESP) by a power cable. In a large wind farm, the ESP might function as a central service facility, with a helicopter landing pad, communications station, crew quarters, and emergency backup equipment. The ESP works as a substation collecting the electricity generated by each turbine. High voltage cables transmit the electricity from the ESP to an onshore substation.

Onshore, the power is integrated into the grid.

Power cables are typically buried beneath the seabed, where they are safer from damage caused by anchors or fishing gear and to reduce their exposure to the marine environment. The cables and their installation are a significant part of the overall cost of building an offshore wind farm. The amount of cable used depends on many factors, including how far offshore the project is located, the spacing between turbines, and maneuvering around obstacles on the ocean floor. Installation must be done carefully to avoid erosion, future movement of the cables, and to avoid reef structures.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

All images courtesy of Dominion Energy

19

U.S. Offshore Windspeeds

Modern Offshore Fixed Turbines Empire State Building 1,454 ft Eiffel Tower 1,063 ft Washington Monument 555 ft Average Onshore US turbine 466 ft

Statue of Liberty 305 ft

Modern Offshore Fixed turbine 853 ft

ONSHORE

Block Island Offshore Wind Project 590 ft

OFFSHORE

Image: NREL

Siting, Planning, and Construction

Water Depth and Underwater Geology

The process of choosing a location to build a wind farm, known as siting, requires consideration of many factors. As with any human endeavor, there are trade-offs, which means that compromises are necessary. With any common resource, we seek to find compromises that are the “highest and best use” of our resources. In the world of real estate, appraisers use four criteria to determine the highest and best use of an area: legal permissibility, physical possibility, financial feasibility, and maximum productivity. When it comes to land offshore and siting a wind farm within a lease area, the questions related to highest and best use can be very complicated because of so many services that this area provides. Wind speeds, water depth, seafloor geology, wildlife, and ship traffic are just some of the considerations planners must consider when siting a wind farm.

The OCS of the Atlantic coast has relatively shallow water. For comparison, the Pacific coast has water that is much deeper.

The shelf area in the Atlantic Ocean, where the CVOW site is, will have waters between 70-125 feet deep. These shallower depths, combined with a mostly sandy bottom, can make for a prime development area. The depth of the sea floor will determine if the towers supporting wind turbines can be attached directly to the sea floor or if they need to float and be tethered to the sea floor.

For deeper waters, recent innovations have made floating offshore wind farms a feasible option, especially for Pacific coast regions.

Wind Speeds Energy produced from wind is directly proportional to the cube of the wind speed. As a result, increased wind speeds of only a few miles per hour can produce a significantly larger amount of electricity. Wind speeds are much greater offshore than onshore in coastal areas, where a population density and energy demands are greater. In the U.S., wind speeds off the Pacific Coast are stronger than the Atlantic Coast or the Gulf of Mexico, however Atlantic Coast wind speeds are consistent enough to provide plenty of reliable wind energy.

Bathymetry studies must be completed and/or analyzed for any offshore installation to help understand the conditions at and below the seafloor. These studies have often required ships to tow sensing and Sonar equipment called a towfish to collect data. Advances in Autonomous Underwater Vehicles (AUVs) are allowing us to collect this information at a much greater rate. Soon we will have much better maps available to help make these kinds of decisions.

Underwater Geology CONTINENTAL SHELF COAST

SHELF BREAK

CONTINENTAL SLOPE CONTINENTAL RISE

ABYSSAL PLAIN OCEAN

VESSEL USING TOWFISH FOR UNDERWATER DATA COLLECTION Image adapted from Bureau of Ocean Energy Management (BOEM)

20

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Wildlife

RIGHT WHALE MIGRATION

The main wildlife concerns related to offshore wind farms siting are for impacts on migratory birds and whales. Knowledge of whale and bird migration patterns is important to ensure that the timing of operations does not coincide with when species are in the area.

Turbine installation is an operation that can create loud noises. In a marine environment, noise can travel very far, and loud noises can be damaging to whales and other species. The right whale is of particular interest to the CVOW facility. During installation, species observers and acoustic monitoring devices will be used to ensure the area is monitored. If a whale enters the area, construction must cease until it has departed from the area.

Summer/Fall Summer/Fall Winter/Spring Spring/Summer

FEEDING GROUNDS

To further protect marine life, such as whales, turtles, and fish, bubble curtains can be used during construction to help form a barrier that will mitigate construction sounds underwater. Air compressors are used to create walls of bubbles. These bubbles reduce sound wave transfer through the water. Siting a facility far enough from the coastline will also help to ensure more safety of avian species (birds), and bats. However, anti-perch devices can be installed to ensure birds do not perch or nest on a stopped turbine.

Wildlife impacts during construction are a major concern. Siting the turbines so that they do not interfere with migratory patterns is also important. But, how does the underwater ecosystem respond after the turbines are in place? While this will continue to be studied for U.S. offshore turbines, diver and AUV images across the globe and even from the pilot turbines in VA waters demonstrate that the turbine components serve to provide a safe structure for reef growth, fish populations, and other marine life.

CALVING GROUNDS Fall/Winter

RIGHT WHALES ATLANTIC OCEAN

The inclusion of calving areas in the habitat protection plan for the North Atlantic right whale has caused federal fisheries managers to study the seismic survey permits more slowly.

Map: NOAA

BUBBLE CURTAIN DURING CONSTRUCTION

Image: Wikimedia Commons

BUBBLE CURTAIN

Image: Wikimedia Commons

©2021 The NEED Project

Image: Dominion Energy

Exploring Offshore Wind Energy

www.NEED.org

21

Shipping Channels and Navigation for Fishing

Wake Effect

When siting a wind farm, engineers must consider the potential for shipping and fishing traffic in the area. In many cases, the concern related to shipping channels has already been considered in the leasing process that gives companies permission to use certain areas of the OCS. High-traffic areas would not be offered for lease as this would be too disruptive to commerce. The distance needed between turbines to allow fishermen to conduct their usual activities varies in some areas. For this reason, engineers will consult local fishermen to gather information and consider their needs.

Naval activity is also important to consider and will often involve high level discussions with government officials. This is of special importance to the CVOW project, as the project is in proximity of the U.S. Naval Fleet Headquarters in Norfolk.

The layout of a wind farm is an important consideration because of how air flows past a turbine. When an air mass collides with a wind turbine, some of the energy it carries is transferred to the turbine to make the blades spin. The removal of that energy from the air mass results in reduced speeds of some groups of air molecules.

This changes the smoothness of the wind moving away from the turbine. This disturbance is called a wake. As the air moves further away it begins to mix and smooth out again.

Map of Shipping Areas

As you design a wind farm, you want to space the turbines such that the air has a chance to smooth out again before it encounters another turbine. To avoid a wake effect between the turbines, engineers must consider the prevailing wind direction and the distance required on average for the air to become smooth again, given the average wind conditions at the site. Engineers create and test models to help make decisions about wind farm layout and space the turbines in patterns to avoid this affect. In some cases, wind farms will require nearly a mile between each turbine, given the conditions.

Wake Effect Behind a Turbine Mobjack Bay

Turbine Rotates Cheapeake Bay

Wind flows in at high energy speeds

Wind smooths out Tail areas of turbulence where wind is slower, less smooth as it exits turbine.

Virginia Beach

CVOW Project Site Restricted Travel Electric Transmission Lines Ship & Navigation Channels

Back Bay

Distance Away

Image: Dominion Energy

22

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Connectivity

Construction

Deciding where to bring power cables on shore is another siting consideration. It wouldn’t make much sense to have a wind farm located in an area where there was no onshore infrastructure with which to connect. Developers and planners will consider the existing electrical grid in the area, coastal geology, and other land uses for the area where they will bring the electricity onshore.

Installing turbines offshore is quite a supply chain feat! First the turbine parts must be built and shipped to a location near to where they will be installed. Turbine blades, towers, nacelles (and the parts within the nacelle) may be constructed in various locations, and each is shipped by boat, train, or truck to a staging area. This staging area is set up in a port that has ample space to store the large components and enable the ships to bring the parts in and out.

The turbines in the CVOW Project will be laid out in a grid-like pattern and connected through a series of offshore cables to one of three offshore substations. The cables will lead from the substations onto shore and into the local electrical grid.

Cables from the turbines are buried under the seafloor and brought onshore near an existing substation to further distribute the electricity. Offshore cabling for CVOW is set to be buried sixteen feet or more below the sea floor. Engineers from existing offshore wind farms in Europe and in Rhode Island have learned that making sure that cables are buried deep enough is also very important. Powerful storms can cause increased movement of sediment on the shore and seafloor in coastal areas. If cables get uncovered, the abrasion from moving sand and rocks can damage cables, the seafloor, and create a dangerous situation. Engineers must study the seafloor and conditions and create a plan at the start of the project to ensure that lines stay safely buried.

Connectivity Diagram for CVOW

Virginia Substations Underwater cables Turbines

TURBINE INSTALLATION VESSEL

A special installation ship is used to transport the monopile (and foundation pieces) out to sea. This vessel is equipped with large cranes and legs. The legs are lowered into the ocean until they can stand stably on the sea floor. The ship will then use the crane and drive the monopile deep into the seabed. Each monopile is made of steel and has a diameter of roughly 30 feet (9 meters) – large enough to drive a car through! The monopile is buried 100 feet (30 meters) into the seabed to provide a stable foundation. A transitional piece is placed on top to make the base for the remaining components.

The ship will install an 800 foot tower, nacelle, and blades onto each base.

These vessels can often load several complete turbines on board in less than 24 hours, and installation of a complete turbine can take less than a day! The CVOW turbines will be installed by a new vessel called the Charybdis. Dominion Energy is leading a consortium to build this installation vessel in Brownsville, Texas. The ship is estimated to cost $500 million, however, it will be very important to developing offshore wind in the U.S., as the U.S. Merchant Marine Act (Jones Act) of 1920 requires that all goods shipped between U.S. ports are transported by U.S. ships and mariners. For wind turbines to be constructed, transported, and installed in U.S. waters, a U.S. Jones Act-compliant ship will be necessary. In June 2021, two U.S. wind developers, Ørsted and Eversource, reached an agreement with Dominion Energy to use Charybdis to install two large-scale offshore wind farms still in development in New England.

BLADE INSTALLATION

Images provided by Dominion Energy

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

23

Careers in Offshore Wind The development and operation of the CVOW Project will create many jobs. Each of the phases of operation will have permanent or temporary jobs created.

Phases of Operation

AUTONOMOUS UNDERWATER VEHICLE (AUV)

Research and Development – Analysts, scientists, and engineers will be needed to develop plans to look at the feasibility, environmental impact, and optimization of planned generation capacity.

Installation and Testing – Jobs will be created where the turbine components are built. Many of these jobs will be in areas where they have the manufacturing experience to create the components.

More jobs will be created in the area or region close to the installation, as the local port will receive, stage, pre-assemble, and load turbine components onto the ship. Mariners and technicians will be called upon to complete phases of marine construction.

Port Authority personnel will also help with the construction and provide lay-down areas for the massive components of the turbine.

Engineers, technicians, electricians, construction specialists, and testing specialists will work to ensure that the turbines are ready to begin producing power and put it on the grid.

Operations and Management – Engineers will be needed to develop, manage, and deliver the resulting power from the wind farm to those who draw power from the grid every day. There will be ongoing jobs for managers, analysts, engineers, technicians, and support personnel of all kinds throughout the life cycle of the project.

Offshore Wind Industry Job Examples Research Scientist - studies and defines the basic science behind our natural systems and provides data to the scientific and technical community Environmental Scientist - studies environmental systems and their interactions often characterizing effects of the built environment on natural systems and animal species Marine Geologist / Geophysicist - studies the geology of our Earth including the makeup of the ocean floor and its component layers Naval Architect - designs marine vessels to particular purposes and to accomplish specific missions Design Engineer - designs major systems and subsystems within any technological machine - ensuring that the component parts work together to handle all loads they encounter and accomplish the design’s overall purpose as efficiently as possible.

Marine Engineer - sub-specialty of mechanical engineering that operates in the marine environment, and designs everything from docks to buoys to systems for ships and other vessels

24

Coastal Engineer - sub-branch of civil engineering that focuses on coastal systems and structures that interact with shorelines and water bodies Mechanical Engineer - engineering field that focuses on mechanical and thermal systems used in technical applications Electrical Engineer – engineering field that focuses on both electrical (power) systems and electronic (control systems) Civil Engineer - engineering field that focuses on the built environment - in buildings, roads, bridges, water, and sewer systems Environmental Engineer - engineering specialty that focuses on the natural environment’s integration with the built environment - often finding innovative ways to accomplish project objectives while addressing problems such as runoff or contamination Wind Turbine Technician - specialized electric and/or mechanical technician who is trained to work on the array of wind turbine systems as well as having specialized safety training that allows them to work at great heights in a safe manner Cable Technician - specialized technician who is responsible for installing and terminating cable systems connecting the turbines to each other and to shore GIS / Mapping Technician - specialized technician who is responsible for providing geographic characterization of the natural environment and precise location of technical systems installed within it Inspection Technician / Drone Pilot/ AUV operator - specialized technician trained to inspect technical systems by operating robotic drone systems with digital video cameras on-board

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Vessel Crew/Mariner - Captains, deck hands, and vessel engineers (on larger vessels) execute shipping, construction, and research missions in oceans and rivers Welders - specialized technicians that are trained to join metals through a variety of technologies and sometimes below the surface of bodies of water, can be land-based or a certified, specialized welding diver Diver - professionals who work under water to inspect, document and repair systems Outside Machinist - professional mechanic capable of installing mechanical systems on vessels Fabricator / Shipfitter - specialized technician that prepares and machines large metal parts to assemble Painter / Coatings Specialist - specialized technician that deals with the application of primers, paints and other coating systems to protect system components

SCUBA DIVER

Rigger / Payload Specialist - specialized technician that deals with safely and efficiently moving and securing loads that are in transport or that are being made into larger assemblies during construction Project Manager - Professional manager that oversees the entire project, from beginning to end, including the integration of the component systems Project Analyst - Professional analyst who reports to the Project Manager and prepares detailed analysis and intelligence on specifically assigned parts of the project Administrative Support Staff - office professionals that support and enable to work of the team to proceed.

Image: Wikimedia Commons

WIND TURBINE TECHNICIAN

WELDER

Image: Wikimedia Commons

Image: Wikimedia Commons

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

25

Build an Anemometer ? Question  How

reliable is an anemometer for calculating wind speed?

0.5 cm

 Materials 1 Pencil 5 Snow cone cups 2 Extra-long straws Masking

tape Hole

punch Scissors

1 Straight pin Marker

Timer

or stopwatch Ruler

Diagram 1

Procedure 1. Cut the end off one cup to make a hole large enough for the pencil to fit in. Use the hole punch to make four holes in the top of the cup: two holes opposite each other very near the rim and two holes on opposite sides about a half-centimeter below the first holes, as shown in Diagram 1.

Diagram 2

2. Slide the straws through the holes in the cup, as shown in Diagram 1.

3. Color one cup so that you can count the revolutions of the anemometer.

REVOLUTIONS PER 10 SEC.

4. Use the hole punch to make two opposite holes in the other cups about 1 centimeter from the rim. Slide one cup onto the end of each straw, making sure the cups face in the same direction. Tape the cups to the straws.

5. Center the straws in the base cup. Slide the base cup over the pencil as shown in Diagram 2 and push the pin through the middle of both straws and into the pencil eraser as far as you can to anchor the apparatus. Lift the straws slightly away from the eraser on the pin so that the apparatus spins easily.

You might need to stretch the pin holes in the straws by pulling gently on the straws while holding the pin in place.

6. Take your anemometer outside and measure the speed of the wind in several areas around the school by counting the number of revolutions in 10 seconds and using the chart to determine miles per hour (mph). Record the time at which each measurement is taken. Compare your results with those of other students in the class.

 Conclusion 1. How did your data compare to that of your class?

2. How could you change the design of your anemometer to make it more reliable?

26

©2021 The NEED Project

2-4 5-7 8-9 10-12 13-15 16-18 19-21 22-23 24-26 27-29 30-32 33-35 36-37 38-40 41-43 44-46 47-49 50-51 52-54 55-57

Exploring Offshore Wind Energy

MPH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 www.NEED.org

Wind Can Do Work ? Question  What

is the maximum load that can be lifted all of the way to the top of the windmill shaft?

 Materials 4-Blade

Windmill Template 1 Extra-long straw 1 Small stirrer straw Masking

tape 50 cm String or thread Paper

clips Large

foam cup

2-3 Straight pins Binder

clip Fan

Ruler

Hole

punch Marker

Scissors

Procedure 1. Turn the cup upside down.

2. Cut the longer straw so that you have an 8 cm length. Share the other portion with another student or group, or discard it. Tape this straw horizontally to the bottom of the cup (which is now the top) so that there is an equal amount of straw on both ends. Set this aside.

3. Prepare the windmill blades using the 4-Blade Windmill Template.

Diagram 1

4. Measure 1.0 cm from the end of the stirrer and make a mark. Insert a pin through the stirrer at this mark. This is the front of the stirrer. See diagram 1 to the right.

5. Slide the stirrer through the windmill template until the back of the template rests against the pin.

Gently slide each blade over the end of the stirrer. Secure the blades to the straw using tape, and a pin.

6. Insert the stirrer into the larger straw on the cup.

7. Tape the string to the end of the stirrer. Tie the other end of the string to a paper clip. Make sure you have 30 cm of string from the straw to the top of the paper clip. See diagram 2 below.

8. On the very end of the stirrer near where the string is attached, fasten a binder clip in place for balance and to keep the string winding around the stirrer.

9. Slide the stirrer forward to bring the binder clip next to the larger straw. Place an extra straight pin through the stirrer as needed to keep the blades away from the cup while still allowing them to move and spin.

10. Place your windmill in front of the fan and observe. Record observations in your science notebooks.

11. Investigate: Keep adding paper clips one at a time to determine the maximum load that can be lifted all of the way to the top. Record your data.

 Conclusion Draw a diagram of the system. Label the energy transformations that occurred in order for work to take place.

 Extensions How

could you change the design of your windmill to produce more work from the system?

What

variables can you change in this investigation? Create a new investigation changing one variable at a time.

Diagram 2 ©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

27

Wind Can Do Work Power Up! Challenge &Background You’ve seen that wind can do work. How much work did your turbine do? To calculate the amount of work, consider the formula, work = force × distance, or W=F×d. Work is measured in Joules, force in Newtons, and distance in meters. In this case, the force exerted was the weight of the paper clips, found by multiplying the mass of the paper clips in kilograms by the acceleration due to gravity, or “g”.

How many paper clips did your turbine lift?

_________________

What is the mass of one paper clip? _________________ grams Mass of all the paper clips your turbine lifted _________________ grams Mass of all the paper clips your turbine lifted in SI (base) units _________________ kg Weight of all the paper clips your turbine lifted (use g = 9.8 m/s2) Distance the paper clips were lifted by the turbine

_________________ N

_________________ cm

Distance the paper clips were lifted in SI (base) units _________________ m Work done by your turbine to lift the paper clips

_________________ J

In order to calculate the power of your turbine, you will need to know how long it took to lift those paper clips. If you didn’t record the time already, take the time to do it now. _________________ s Power is the rate at which work is done, or power = work ÷ time. Thus, the amount of time it takes to do the work is just as important as the work itself when calculating power. It doesn’t do much good to move 2 tons 50 meters if it takes 2 months to do so. Power is measured in Watts, work is measured in Joules, and time is measured in seconds.

The work done by your turbine to lift the paper clips was _______________ J The time required by your turbine to do the work was _________________ s The power of your turbine was _________________ W How can you increase the power of your wind turbine? There are two main areas of focus: 1. You can ______________ the amount of time required to lift the same number of paper clips.

2. You can ______________ the number of paper clips your turbine can lift in the same amount of time.

? Question  What

modifications can be made to your Wind Can Do Work model turbine to make it more powerful?

 Hypothesis Draft a hypothesis to answer the question using an “If...then...because...” format.

 Materials FOR EACH STUDENT OR PAIR Model

wind turbines from Wind Can Do Work activity Stopwatch

or student timer Paper

clips Recycled

or reclaimed materials for improving your turbine, such as cardboard, clean plastic bottles, scrap craft wood, etc.

Construction

and craft tools such as utility knives, scissors, glue, tape, pliers, etc.

28

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Procedure 1. Decide which approach you will use to increase the power of your turbine. Will you change the time it takes to lift the paper clips, or will you change how many paper clips the turbine can lift at once?

2. Set a goal. Would you like to double the power? Triple it? Increase it by an additional 50 percent? Write your goal below.

I would like to increase the power of the turbine by ___________________.

3. Observe your turbine to see where improvements can be made. Make a sketch and note on the sketch the area(s) on which you would like to focus.

4. Approach the Power Up! Challenge systematically. Modify one part or group of parts at a time, test, note the power change, and modify again if necessary. Then move on to the next area of focus until you reach your power increase goal.

5. Document your results on paper, in photos, or in video, and report your findings to the rest of the class at the end of the challenge.

Rules for Improving Turbines 1. The speed of the air moving your turbine must remain constant. You may not increase or decrease the speed of the fan motor.

2. You may not use any portion of a pre-assembled model wind turbine, engineering building set, plastic building brick set, or something similar. All parts added to your turbine must be hand-made by you or your group.

3. All work being done must be by the turbine. You may not add any mechanical advantage that does work, such as a motor, lever, spring, etc., nor may you combine two turbines to work in combination.

Conclusions 1. How did you decide to increase the power of your turbine? Why did you choose this focus?

2. Describe an obstacle you encountered in trying to increase the power of your turbine. What did you do to overcome it?

3. If you had more time, what would you do next to improve your turbine?

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

29

Measuring Electricity Multimeters are tools used to measure electricity. The multimeter allows you to measure current, resistance, and voltage, and displays the reading numerically.

When using a multimeter it should be noted that some measurements will never “stay still” at a single repeatable value. This is the nature of the variables being monitored in some circumstances. For example, if you were to measure the resistance between your two hands with the ohmmeter setting on the multimeter (megohm range—millions of ohms), you would find that the values would continuously change.

How tightly you squeeze the metal probes and how “wet” or “dry” your skin might be can have a sizable effect on the reading that you obtain. In this situation you need a protocol or standardized method to allow you to record data.

Digital Multimeter

(NOT USED)

Directions DC VOLTAGE 1. Connect RED lead to VΩmA jack and BLACK to COM. 2. Set ROTARY SWITCH to the highest setting on the DC VOLTAGE scale (1000).

3. Connect leads to the device to be tested using the alligator clips provided.

4. Adjust ROTARY SWITCH to lower settings until a satisfactory reading is obtained.

5. With the water turbine, usually the 20 DCV setting provides the best reading.

DC CURRENT MUST INCLUDE A LOAD IN THE CIRCUIT - NOT NECESSARY FOR THESE ACTIVITIES 1. Connect RED lead to VΩmA jack and BLACK to COM. 2. Set ROTARY SWITCH to 10 ADC setting.

3. Connect leads to the device to be tested using the alligator clips provided.

Note: The reading indicates DC AMPS; a reading of 0.25 amps equals 250 ma (milliamps).

YOUR MULTIMETER MIGHT BE SLIGHTLY DIFFERENT FROM THE ONE SHOWN. BEFORE USING THE MULTIMETER, READ THE OPERATOR’S INSTRUCTION MANUAL INCLUDED IN THE BOX FOR SAFETY INFORMATION AND COMPLETE OPERATING INSTRUCTIONS.

30

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Wind Can Generate Electricity Background A wind turbine uses the motion energy in the wind to generate electricity. A generator helps transfer the motion energy to electrical energy using magnets and wire. You will use the completed Wind Can Do Work model to create this wind turbine generator. This activity will help you to transform the paper clip lifting model into an electrified wind turbine. Your Wind Can Do Work model’s blades, rotor (stirrer straw), and monopile base (cup) will all transform wind energy into motion energy. But, now your model will spin a magnet instead of string.

A changing magnetic field can induce an electrical current, especially if the electrons are given a path through which to pass their charge.

By wrapping magnetic coated wire, you’ll have the opportunity to build your own copper coils. The spinning magnetic force created by the spinning magnets will push the negatively charged electrons through these coils. If you can move electrons, you’re generating electricity!

? Questions  How

is electricity generated?

How

can wind do work to generate electricity?

 Materials Assembled

Wind Can Do Work Turbine Model (With Red/White Coffee Stirrer) Magnet

wire 2 Neodymium Magnets Multimeter

2 Alligator Clips Nacelle

Template

Magnet

Templates Toilet

paper roll Hot

glue gun with glue Ruler

Scissors

Tape

Sandpaper

Procedure BUILDING YOUR NACELLE 1. Flatten your toilet paper roll.

2. Cut out the Nacelle Template. Hold or tape the Nacelle Template in the vertical center of the toilet paper roll. The pointed edges of the Nacelle Template will be 1.8 cm from the open edges of the toilet paper roll.

3. Once the Nacelle Template is in place, trace the shape onto the roll and carefully cut it out. Reshape the toilet paper roll.

4. Unclip the binder clip from the back of your original wind turbine’s rotor (stirrer straw) and set the rotor/blades aside.

5. Remove the pins from the stirrer and set them aside.

6. Place the toilet paper roll over the smaller end of the cup. Adjust the roll so that it runs parallel to the straw on the top of the turbine, with the straw running directly down the center of the toilet paper roll.

7. Connect the toilet paper roll to the cup by placing one large piece of tape over the toilet paper roll and cup, perpendicular to the toilet paper roll. It should extend from the side of the cup, over the roll, and to the other side of the cup.

INSTALLING THE COPPER COILS 1. Tape the ends of the toilet paper roll in place to help wrap your coils. Extend a piece of tape from one side of the toilet paper roll’s bottom and connect it to the side of the cup directly underneath. Make sure the tape covers the gap between the cup and roll. Repeat for the other side of the roll.

2. Leave a 20 cm tail of magnetic wire hanging off the side of the roll. Tape the wire in place. Begin wrapping the wire around one end of the toilet paper roll. Complete 150 or more wraps of magnetic wire around one end of the toilet paper roll. Wire wraps should be tight and close together. Tape the wrapped coil of wires as needed to prevent unspooling.

3. After at least 150 wraps, secure the coil in place with tape to keep your coils intact and in place.

4. Continue the wire across the top of the toilet paper roll (without cutting) to the other end of the tube. Tape the wire near the edge of the other side, where you’d like to start wrapping your next coil.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

31

5. Start wrapping the wire in the same direction that you wrapped the other end. Complete 150 or more wraps of magnetic wire around this end of the toilet paper roll. Tape the wrapped coil of wires as needed to prevent unspooling.

6. After at least 150 wraps, tape the coil in place with tape to keep the coil intact and in place.

7. Leave a 20 cm tail of wire on this side. Cut the wire.

INSTALLING THE MAGNETS 1. Cut out both Magnet Templates. Fold Tabs A and B inward on the dotted lines on both templates.

2. Line up the edge of Tab A on on one template to one end of one magnet and hot glue it in place, up to the dotted line. Line up the edge of Tab B to the other end of the magnet and hot glue it in place, up to the dotted line. This will leave a small gap between the paper and magnet. Repeat for the second magnet.

3. Slide one magnet onto the stirrer, so it is next to the blades. Reinsert the pin into the stirrer on the opposite side of magnet.

4. Slide the coffee stirrer back into the large straw in the center of the toilet paper roll. Slide the other magnet onto the other end of the coffee stirrer.

5. Adjust your magnets and pin placement. The magnets should spin in the middle of your copper coils as the blade spins freely.

Mark the locations of the magnets and pins using a permanent marker.

6. Remove the back magnet from the stirrer and remove the stirrer from the large straw. Remove the pin from the coffee stirrer.

7. Add a bead of hot glue to the blade end of the stirrer up to the side of the marker line. Slide the magnet onto this line of hot glue so that it lines up with your marker line. Add additional glue as needed.

8. Reinsert the pin next to the blade-side magnet at your marker line. Insert the stirrer into the large straw. The pin should allow the rotor to spin freely.

9. Add a bead of hot glue to the back end of the coffee stirrer up to the side of the marker line. Slide the magnet onto this line of hot glue so that it lines up with your marker line. Add additional glue as needed.

TESTING YOUR WIND TURBINE: 1. Sand the enamel coating off of the ends of the 2 wire “tails” on your nacelle (toilet paper roll).

2. Connect the alligator clips to each of your wind turbine’s wire leads.

3. Connect your multimeter to the alligator clips. Set your multimeter to 200 mV and start the fan to spin your blades.

4. If the voltage is consistently negative, switch the alligator clips.

5. Once you have a consistently positive voltage, add a small flag of tape to each wire lead coming off of the wind turbine.

6. Mark the wire lead that is connected to the red terminal on the multimeter as positive by drawing a “+” on its tape flag. Mark the wire lead that is connected to the black terminal on the multimeter as positive by drawing a “-” on its tape flag.

 Data and Analysis 1. Record your output and fan speed.

2. Adjust the fan speed. How does the output change? Is there an optimal wind speed range?

3. Change the orientation and positioning of your turbine. How does the output change?

 Conclusion 1. How is energy transformed when generating electricity using a wind turbine?

2. What components are necessary for generating electricity?

3. How are wind speed and generation output correlated?

32

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Siting an Offshore Wind Farm You have been tasked with developing an offshore wind farm proposal for open lease areas. Create a proposal for your offshore wind farm that considers the concerns of other stakeholder groups that utilize the area.

Essential questions: Where

will you bring power onshore and connect to the grid? Justify your decision.

How

many turbines will you include in your lease area and how far? What will be the distance between turbines, and how will they be arranged? Justify your decision.

What

time of year will you install the support towers? Explain.

Procedure 1. Review the background information about offshore wind farm siting in the student text.

2. Navigate to https://www.northeastoceandata.org/data-explorer/.

3. Explore different data layers related to siting considerations from the student text. Add others or narrow your list based on teacher instructions. Gather data and make notes on your observations from the GIS information.  To view wind speed information, go to “Physical Oceanography” and select the layer “Contours-Mean Annual Offshore Windspeeds (m/s)”. Once the layer is selected, the legend indicating the values of the colors will appear in the lower left panel.  Existing lease areas can be visualized by clicking “Energy & Infrastructure”, "Planning Areas", and then “Lease Areas”.  To learn about transmission options, go to “Energy & Infrastructure” and then click on “Infrastructure” to find layers for electrical transmission lines and transmission substations.  To get greater detail about depth, go to “Bathymetry & Imagery” and explore the options there.  Explore the information available about birds and fish.  Investigate ship navigation patterns by clicking on “Marine Transportation” and explore the different types of information available.

NOTE: Marine mammal information is also located in this section.

4. Consult wind speed maps and other resources for your site as needed.

5. Based on the information you have collected, develop a siting plan for an offshore windfarm. Your plan should outline the following information: location, advantages, challenges, connectivity, layout, and construction. Don’t forget to prepare justifications for your plans.

6. Share your proposal with your class using a digital presentation.

Northeast Ocean Data Geographic Information Systems (GIS) are powerful tools for reviewing lots of spatial information and identifying patterns.

Northeast Ocean Data is a web app that includes many data layers related to the siting of offshore wind farms. Take some time to find and explore the layers relevant to your task.

If asked to share your justification for your proposed plan, you can take screenshots of your map and include that in your explanation.

https://www.northeastoceandata.org/data-explorer/ ©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

33

Baseload Balance STUDENT WORKSHEET

In the box to the right, calculate the total baseload demand.

BASELOAD DEMAND

In the column labeled TOTAL ONLINE, calculate the total demand for each hour of operation.

RESIDENTIAL

35 MW

HEAVY INDUSTRIAL

60 MW

In the column labeled +15%, calculate the total demand required for an additional 15% demand.

COMMERCIAL

20 MW

TOTAL ONLINE TOTAL BASELOAD

In the columns below, record the time that generation sources come online and go offline.

TOTAL

+15% BASELOAD GENERATION

PEAK COMING ONLINE

DEMAND

COAL BASELOAD

40 MW

$50/MW

7:00 AM-12:00 AM

5 MW

NATURAL GAS BASELOAD

20 MW

$30/MW

8:00 AM-9:00 PM

5 MW

NUCLEAR BASELOAD

50 MW

$30/MW

8:00 AM-11:00 PM

10 MW

HYDROPOWER BASELOAD

5 MW

$30/MW

9:00 AM-8:00 PM

5 MW

SOLAR BASELOAD

5 MW

$40/MW

9:00 AM-9:00 PM

10 MW

WIND BASELOAD

5 MW

$40/MW

10:00 AM-8:00 PM

5 MW

NATURAL GAS BASELOAD

15 MW

$40/MW

3:00 PM-1:00 AM

10 MW

WASTE-TO-ENERGY BASELOAD

10 MW

$60/MW

5:00 PM-11:00 PM

5 MW PEAK GENERATION

GOING OFFLINE

NATURAL GAS SIMPLE CYCLE

5 MW

$250/MW

30 MIN

NATURAL GAS SIMPLE CYCLE

10 MW

$90/MW

30 MIN

8:00 PM

LOSE 10 MW

(2 TAGS)

NATURAL GAS SIMPLE CYCLE

5 MW

$90/MW

30 MIN

9:00 PM

LOSE 15 MW

(2 TAGS)

NATURAL GAS SIMPLE CYCLE

10 MW

$150/MW

30 MIN

11:00 PM

LOSE 15 MW

(2 TAGS)

NATURAL GAS SIMPLE CYCLE

5 MW

$200/MW

30 MIN

12:00 AM

LOSE 5 MW

(1 TAG)

HYDROPOWER PEAK

10 MW

$70/MW

5 MIN

1:00 AM

LOSE 10 MW

(1 TAG)

HYDROPOWER PEAK

5 MW

$50/MW

5 MIN

HYDROPOWER PEAK

10 MW

$90/MW

5 MIN

TIME

TIME

ONLINE

OFFLINE

TIME

TIME

ONLINE

OFFLINE

STORAGE OPTIONS COMPRESSED AIR

10 MW

PUMPED STORAGE HYDRO

20 MW

FLYWHEEL

5 MW

SOLAR THERMAL

10 MW

BATTERY

20 MW

pumped storage max 10 hours availability flywheel max 5 minute availability battery storage max 4 hours availability

34

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Basic Measurement Values in Electronics SYMBOL

VALUE

METER

UNIT

V

Voltage (the force)

Voltmeter

volt

I

Current (the flow)

Ammeter

ampere

R

Resistance (the anti-flow)

Ohmmeter

Ohm

1 ampere = 1 coulomb/second 1 coulomb = 6.24 x 1018 electrons (about a triple axle dump truck full of sand where one grain of sand is one electron)

Prefixes for Units SMALLER

(m)illi x 1/1 000 or 0.001 (µ) micro x 1/1 000 000 or 0.000 001 (n)ano x1/100 000 000 or 0.000 000 001 (p)ico x 1/1 000 000 000 000 or 0.000 000 000 001

BIGGER

(k)ilo x 1,000 (M)ega x 1,000,000 (G)iga x 1,000,000,000

Formulas for Measuring Electricity The formula pie works for any three variable equation. Put your finger on the variable you want to solve for and the operation you need is revealed.

V=IxR I = V/R R = V/I

SERIES RESISTANCE (RESISTANCE IS ADDITIVE) RT= R1 + R2 + R3… +Rn

PARALLEL RESISTANCE (RESISTANCE IS RECIPROCAL) 1/RT= 1/R1 + 1/R2+ 1/R3… +1/Rn Note: ALWAYS convert the values you are working with to the “BASE unit.” For example, don’t plug kiloohms (kΩ) into the equation—convert the value to ohms first.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

35

1. Exploring Blade Pitch ? Question  How

does the blade’s pitch (angle) affect the turbine’s electrical output?

 Hypothesis Make a hypothesis to address the question using the following format: If (manipulated variable) then (responding variable) because ...

Independent Variable: Blade Pitch Dependent Variable: Electrical Output Controlled Variables:

 Materials Poster

board Dowels

Scissors

Masking

tape Hub

Protractor

Turbine

testing station (turbine tower, multimeter, fan) Benchmark

Blade Template

Procedure 1. Using the benchmark blade template, make three blades out of poster board.

Space them evenly around the hub.

2. Slip the protractor around the dowel. Set the blades to a pitch of 90 degrees.

3. Put your hub on the turbine tower and observe the results. Record the data.

4. Set your blades to a new pitch and test again. This is your second trial. Record your data.

5. Repeat Step 4 at least once more to try to find the optimum pitch for the greatest electrical output.

 Data Table PITCH TRIAL 1

ELECTRICAL OUTPUT (VOLTAGE)

90 DEGREES

TRIAL 2 TRIAL 3

 Graph Data The manipulated variable is written on the X axis (horizontal) and the responding variable is written on the Y axis (vertical).

 Conclusion Do you accept or reject your hypothesis? Use results from your data table to support your reasoning and explain which blade pitch you will proceed with for your next investigations and why.

Note: The pitch you found to be optimal for the greatest electrical output will now be a controlled variable. In future explorations you will continue to use this pitch as you investigate.

36

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

2. Exploring Number of Blades ? Question  How

do the number of blades on a turbine affect electrical output?

 Hypothesis Make a hypothesis to address the question using the following format: If (manipulated variable) then (responding variable) because ...

Independent Variable: Number of Blades Dependent Variable: Electrical Output Controlled Variables:

 Materials Benchmark

blades Poster

board Dowels

Scissors

Masking

tape Hub

Turbine

testing station Protractor

Procedure 1. Decide how many blades you will be testing and make enough blades for the maximum number you will be testing.

2. In the data table, put down the greatest electrical output from the blade pitch investigation of the three benchmark blades.

3. Put the number of blades you want to test into the hub. They should have the same pitch as in the previous investigation.

4. Put your hub onto the turbine tower and test the number of blades. Record the results as trial 1.

5. Repeat steps 3-4 at least two more times to try to find the optimum number of blades for the greatest electrical output.

 Data Table NUMBER OF BLADES BENCHMARK

ELECTRICAL OUTPUT (VOLTAGE)

3 BLADES

TRIAL 1 TRIAL 2 TRIAL 3

 Graph Data The manipulated variable is written on the X axis (horizontal) and the responding variable is written on the Y axis (vertical).

 Conclusion Do you accept or reject your hypothesis? Use results from your data table to support your reasoning and explain how many blades are ideal for a turbine.

Note: The number of blades with the greatest electrical output should become the benchmark blades for your next investigation.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

37

3. Exploring Surface Area ? Question  How

does the surface area of a turbine blade affect electrical output?

 Hypothesis Make a hypothesis to address the question using the following format: If (manipulated variable) then (responding variable) because ...

Independent Variable: ___________________________________ Dependent Variable:

____________________________________

Controlled Variables:

 Materials Benchmark

blades Poster

board Dowels

Scissors

Masking

tape

Hub

Turbine

testing station Protractor

Ruler

 Formula

b1

Area of a trapezoid = ½(b1 + b2) h

h b2

Procedure 1. Calculate the surface area of the benchmark blade. In the data table, record the surface area and the greatest electrical output from your previous investigation of the benchmark blades. The formula for finding the area of a trapezoid is one half the sum of both bases, multiplied by the height or, a=1/2 (b1 + b2) h.

2. Keep the same shape as the benchmark blade, but change the length and/or width. This will change the surface area of the blade.

3. Make your new blades. You should have the same number of blades that you found had the best results in your previous investigation.

4. Find the surface area for each of your new blades.

5. Put your blades into the hub and onto the turbine tower. Test for electrical output and record data.

6. Repeat steps 2-5 at least two more times to try to find the optimum surface area for the greatest electrical output.

 Data Table SURFACE AREA

ELECTRICAL OUTPUT (VOLTAGE)

BENCHMARK TRIAL 1 TRIAL 2 TRIAL 3

 Graph Data The manipulated variable is written on the X axis (horizontal) and the responding variable is written on the Y axis (vertical).

 Conclusion Do you accept or reject your hypothesis? Use results from your data table to support your reasoning and explain how surface area affects the electrical output. Why do you think this is?

Note: The blades with the surface area that achieved the greatest electrical output should become the optimum blades for your next investigation.

38

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

4. Exploring Mass ? Question  How

does adding mass to the blades affect the turbine’s electrical output?

 Hypothesis Make a hypothesis to address the question using the following format: If (manipulated variable) then (responding variable) because ...

Independent Variable: ___________________________________ Dependent Variable:

____________________________________

Controlled Variables:

 Materials

Blade

Optimum

blades from previous investigation Pennies

(or other mass) Masking

tape Turbine

testing station Protractor

Procedure 1. In the data table, record your results from your previous investigation on the row with zero grams.

1c

1c

1c

1c

1c

1c

1c

1c

Pennies

Tape

2. Tape one penny near the base of each blade, an equal distance from the center of the hub.

3. Test and record the electrical output. Repeat, adding another penny. If adding mass increases the output, add more pennies one at a time until you determine the ideal mass for the greatest electrical output.

Dowel

4. Distribute the pennies on the blades at different distances from the hub until you determine the optimal distribution of mass for the greatest electrical output.

 Data Table ADDITIONAL MASS OPTIMUM

ELECTRICAL OUTPUT (VOLTAGE)

0 GRAMS

TRIAL 1 TRIAL 2 TRIAL 3

 Graph Data The manipulated variable is written on the X axis (horizontal) and the responding variable is written on the Y axis (vertical).

 Conclusion Do you accept or reject your hypothesis? Use results from your data table to support your reasoning and explain how mass and mass distribution affect the electrical output. Why do you think this is?

Note: The blades with the mass that achieved the greatest electrical output should become the optimum blades or be considered for any further investigations, such as gear ratios and aerodynamics. ©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

39

Blade Aerodynamics Graphic Organizer ? Questions  How

do drag, lift, and torque influence the efficiency of a wind turbine?

Why

do turbine blades move in the wind?

Define apparent wind:

DRAG

LIFT

TORQUE

40

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Blade Aerodynamics ? Question  How

do drag, lift, and torque influence the efficiency of a wind turbine?

 Observations How does the shape of the blade in this demonstration differ from your original benchmark blades?

How many airfoil blades provide the optimal electrical output? Compare this to your findings from the previous explorations, and explain any similarity or difference.

How is blade pitch affected when using an airfoil blade? Compare to your findings from previous explorations, and explain any similarity or difference.

Describe how mass and surface area may be affected when using airfoil blades. Is there a shape of blade that works best? Cite evidence from previous investigations in your answer.

 Conclusion 1. Would you choose to use an airfoil shape if designing the optimum blade for efficiency? Why or why not?

2. Describe what your plan might look like if you were to design the optimum blades for an actual wind turbine to be placed at your school.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

41

Designing Optimum Blades ! Challenge  The engineers at Wind for Tomorrow Turbine Co. want help to optimize their turbine blades for higher energy output. They are accepting bids from companies to design blades that more effectively convert kinetic energy than their current blade design.

! Explore  Using data from your previous investigations and data from other groups, explore ideas for the best blade design.

Make a Plan In your science notebook, sketch your design, list the materials you will need, and detail the steps you will take to make the blades.

Construct blades that will give you the greatest electrical output.

 Data Test and record the electrical output from your new blades. Compare your data to the benchmark blades in Blade Investigation #1 and your optimum blades in Blade Investigation #4.

 Data Table BLADES

ELECTRICAL OUTPUT (VOLTAGE)

INVESTIGATION #4 OPTIMUM BLADES AIRFOIL TEST BLADES 1ST DESIGN 2ND DESIGN

 Analysis How did the output of your new blades compare to the output of the airfoil blades and the optimum blades from the #4 investigation? In your science notebook, explain why your blade design is more or less effective than the comparison blades.

New Plan Using your data from the data table above, draw and describe specific changes you will make to your blade design to increase its electrical output and why you will make these changes.

 Redesign Using your changes, alter the design of your blades, test, and record your data.

 Analysis How did the outcome of your re-designed blades compare to the output of the airfoil blades, the optimum blades, and your first design?

Explain your results.

 Report Write a report to the Wind for Tomorrow Turbine Co. detailing your best blade design. Use data to explain why the company should or should not go with your design.

42

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Investigating Gear Ratios ? Question  How

do different gear ratios within the gear box affect the electrical output of a turbine?

 Hypothesis Make a hypothesis to address the question using the following format: If (manipulated variable) then (responding variable) because ...

Independent Variable: ____________________________________ Dependent Variable:

____________________________________

Controlled Variables:

 Materials Multimeter

Fan

Turbine

Gears

Optimum

blades (from the previous investigation or investigation #4) Watch

with second hand Protractor

Procedure 1. In the table below, record your results from the previous investigation where you used the turbine with the standard gear ratio of 64:8 (64=tooth gear and 8=tooth gear).

2. Configure a new gear ratio (for example 32:8) with the turbine, making sure that you minimize all other variables (keep everything else the same). You have the option of three gear ratios (64:8, 32:8 or 16:8 – additional adjustment is required for 16:8 gear ratio).

3. Turn the fan on and record the voltage output every 20 seconds for one minute. Record your results below and find the average.

4. Test different gear ratios to compare their effect on voltage output.

 Data Table 20 SECONDS

40 SECONDS

60 SECONDS

AVERAGE

STANDARD GEAR, BEST RESULTS GEAR RATIO 1 GEAR RATIO 2 GEAR RATIO 3

 Conclusion 1. Were the different gear ratios giving you consistent results? Why or why not?

2. What did you notice about the different gear ratios?

3. What did you notice about rotations per minute?

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

43

Calculating Wind Power ? Question  How

do you calculate wind power?

 Materials Fan

Wind

gauge Turbine

with benchmark blades Meter

stick

 Formula Power = ½ ρAV3 where ρ = air density (ρ = 1.2 kg/m3 at standard ambient temperature and pressure); A = swept area (A = πr2 ; π = 3.1416); V = velocity

Watts = ½ (kg/m3) x (m2) x (m/s)3

Procedure 1. Measure the radius of the turbine blade assembly and calculate the area swept by the blades.

(A = πr2)

2. Use the wind gauge to measure the wind velocity at a distance of 1 meter from the fan on low and high speeds. Convert the measurements from miles per hour to meters per second (m/s).

(1 mile = 1609.344 meters)

Wind Velocity at Low Speed - 1 meter:

____________ mph = ____________m/s

Wind Velocity at High Speed - 1 meter:

____________ mph = ____________m/s

3. Use the formula above to calculate the power of the wind in watts at both fan speeds.

Wind Power at Low Speed - 1 meter:

____________W

Wind Power at High Speed - 1 meter:

____________W

4. Vary the distance from the fan and calculate the power on low and high speeds.

Wind Power at ___________m (distance A) on Low Speed: ___________W

Wind Power at ___________m (distance A) on High Speed: ___________W

Wind Power at ___________m (distance B) on Low Speed: ___________W

Wind Power at ___________m (distance B) on High Speed: ___________W

 Conclusion 1. Compare the power at different distances from the fan and on different fan speeds.

2. Explain the relationships between the different variables and the power produced.

44

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

Offshore Wind Turbine Test Background Fixed offshore wind turbines are constructed with the same general design as wind turbines onshore. However, offshore wind turbines are installed very differently, based on the underwater environment and the conditions at sea. You will use the completed Wind Can Generate Electricity model to build an offshore wind turbine model and take a closer look at how installation, construction, and the operation of offshore turbines are impacted by the seafloor and the ocean. The tower and foundation, or monopile, extend into the water and are driven into the ocean floor. Monopile foundations can be used in waters up to 160 feet (50 m) deep and are excellent for sand or clay seabeds.

This wind turbine model will have you install a more realistically proportioned monopile and mount it in your own small portion of the ocean.

? Question  How

does the seafloor or seabed geology impact the structure, installation, and operation of an offshore turbine?

 Materials Assembled

Wind Can Generate Electricity model 1 Large milkshake/boba straw Masking

Tape Multimeter

Alligator

clips Cardboard

Sand

Scissors

Hot

glue gun with glue sticks Empty

water or soda bottle Water

Ruler

Fan

Monopile

Template

Preparing Your Offshore Nacelle 1. Measure 3.75 cm (1.5 inches) from the top of your Wind Can Generate Electricity turbine. Make multiple marks along the side of the cup.

2. Connect these marks into one long line around the side of the foam cup.

3. Carefully cut along these marks to remove nacelle from your old monopile (foam cup).

4. Set aside the nacelle and discard the remaining foam.

Installing Your Offshore Monopile 1. Cut out the Monopile Template and trace it onto a piece of cardboard.

2. Cut out the circular piece of cardboard.

3. Wrap tape around the end of the large straw to insulate it.

4. Extrude hot glue onto the center of the circular piece of cardboard. Apply enough hot glue to connect the taped straw to the cardboard.

5. Place the straw in the hot glue, tape side down and perpendicular to the cardboard circle. Hold it in place until the hot glue cools.

6. Apply a bead of hot glue at the base of the straw all the way around to further weld the straw to the cardboard.

7. Flip the straw/cardboard monopile so that the cardboard circle is at the top.

8. Cover the top of the cardboard circle with hot glue and slide your nacelle from Wind Can Generate Electricity on top. The cardboard circle should fit exactly into the base of the foam cup nacelle. Hold everything in place until the hot glue cools.

Siting Your Offshore Wind Turbine 1. Remove the label from a used and rinsed soda or water bottle.

2. Carefully cut the top third or top half off of the bottle.

3. Fill the remaining bottle halfway with sand and fill the remaining space with water.

4. Insert your turbine’s straw monopile into the sand and water site.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

45

Testing Your Offshore Wind Turbine: 1. Connect the alligator clips to each of your wind turbine’s magnetic wire leads.

2. Connect your multimeter to the alligator clips. Set your multimeter to 200 mV and start the fan to spin your blades.

 Data and Analysis 1. Record your output and fan speed. Note how your turbine is operating and if there is any change in the monopile’s orientation relative to the water. Note any changes to the foundation (where the monopile is inserted into the sand).

2. Adjust the fan speed and record output differential. Note any changes in the turbine’s foundation or orientation.

 Conclusion 1. How was your turbine’s foundation impacted by wind speed, water, and the seafloor geology?

2. How could you alter your design to better match the conditions and challenges your turbine faced for operation?

3. How do you think the density or conditions (fine, medium, etc.) of the sand in the seafloor will impact your foundation?

4. How do you think your monopile turbine would fare if the seafloor geology was made of loosely packed, soft silt? Gravel? Soft clay?

How would you alter your foundation construction for each of these conditions?

 Extensions Test

out various seafloor geologies (dry sand, wet set, soil, gravel, etc.). Redesign your foundation to suit the various seabed conditions.

Create

a wind farm with multiple turbines from your class using a plastic tub instead of a water bottle. Explore how the seafloor might change with more disturbance. Explore how several turbines in close proximity can be affected by the wake from nearby turbines. Does it have any impact on your turbine’s foundation and structure?

How

would your model fare in extremely deep water? How could you redesign your foundation and structure for these conditions?

46

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

a

b

c

Glossary

aerodynamics

the study of the motion of air and its interactions with solid objects

air density

mass per unit volume of Earth’s atmosphere

airfoil

the shape of a blade or wing from a side or cross-sectional view

anemometer

instrument used for measuring wind speed

atom

the most basic unit of matter

autonomous underwater vehicle (AUV)

autonomous underwater vehicle (AUV) an unmanned, untethered underwater vehicle or robot that can be used for surveying, mapping, and navigations

baseload

minimum power a utility must provide to consumers

bathymetry

measurement of depth in oceans, lakes, or large bodies of wate

Bernoulli’s Principle

the pressure in a fluid is reduced as the flow speed increases

Betz Limit

the maximum amount of kinetic energy of the wind that can be converted into mechanical or motion energy turning the rotor on a turbine, defined by German physicist Albert Betz

blade

individual moving component of a turbine that is responsible for transferring energy

chemical energy

energy stored in the chemical bonds of a substance and released during a chemical reaction such as burning wood, coal, or oil

circuit

a conductor or a system of conductors through which electric current flows

current

flow of electric charge through a conductor; measured in amperes or amps

cyclone

winds that rotate rapidly inward to areas of lower atmospheric pressure, often associated with severe weather

direct drive

a wind turbine design where the blades spin the generator directly without gears

drag

a mechanical force that acts on a solid object interacting with a fluid, typically slowing down a moving item or system

efficiency

the ratio of energy delivered by a machine to the energy supplied for its operation; often refers to reducing energy consumption by using technologically advanced equipment without affecting the service provided

elastic energy

energy stored through the application of a force to stretch or compress an item

electric grid

network of power stations, power lines, and transformers used to deliver electricity from generation to consumers

electrical energy

the energy associated with electric charges and their movements

electricity

a form of energy created by the movement of electrons

electromagnetism

the interaction of forces occurring between electrically charged particles that can create an electric field or magnetic field

electron

very tiny, negatively charged subatomic particle that moves around the nucleus of the atom

element

most pure form of all matter; all matter is made of elements or combinations of elements

energy

the ability to do work, produce change, or move an object; electrical energy is usually measured in kilowatt-hours (kWh), while heat energy is usually measured in British thermal units (Btu)

energy level

area where electrons can be found; describes the probable amount of energy in the atom

front

a term used when discussing weather describing the boundary lines between masses of air with different densities; often associated with changes in wind speed

gear box

device used in wind turbines to convert the slow rotation of the blades and rotor to a faster rotation in order to produce electricity

gear ratio

relationship between large and small gears in a generator

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

47

generator

a device that produces electricity by converting motion energy into electrical energy with spinning coils of wire and magnets

generation

refers to the creation of electric power by a generator

gravitational potential energy

energy of position or place

lift

a force that is perpendicular to the oncoming flow; allows objects to fly; opposes drag

load

a device or system that draws or uses electricity

kinetic energy

the energy of a body which results from its motion

magnet

material with pairs of non-cancelling, spinning electrons that line up to form a magnetic field; magnetic materials are attracted to each other

magnetic field

the area of force surrounding a magnet

megawatt

standard unit of measurement for bulk electricity in power plants; 1 megawatt (MW) = 1 million watts

monopile

large, single structure driven into the Earth to support another structure, such as an offshore wind turbine

motion energy

the displacement of objects and substances from one place to another

nacelle

the housing where all of the generating components are found within a turbine

nautical mile neutron

subatomic particle with no electric charge, found in the nucleus of the atom

Newton’s Laws of Motion

laws that govern the motion of all items when a force is applied

nonrenewable energy sources

sources of energy with limited supply due to their inability to be renewed or produced in a short amount of time

nuclear energy

energy stored in the nucleus of an atom that is released by the joining or splitting of the nuclei

nucleus

the center of an atom, composed of protons and neutrons and houses the majority of the atom’s mass

Ohm's Law

the law that explains the relationship between current, voltage, and resistance in an electrical circuit; in all electrical circuits, the current (I) of that circuit is directly proportional to the voltage (V) applied to that circuit and inversely proportional to the resistance (R) of that same circuit

Outer Continental Shelf

offshore federal domain where deposits of oil and natural gas and ample wind resources can be found

peak demand

a period where many cutomers want electricity at the same time; often takes place during the day; utilities need to generate additional power to balance loads

pitch

the angle of the blade on a turbine, can be adjusted to reduce drag

potential energy

the energy stored within a body, due to place or position

power

the rate at which energy is transferred; electrical energy is usually measured in watts; also used for a measurement of capacity

proton

subatomic particle with a positive electric charge, found in the nucleus of an atom

radiant energy

energy that travels in electromagnetic waves like light or x-rays

renewable energy sources

sources of energy with a more constant supply because they are replenished in a short amount of time

rotor hub

structure connecting the blades of the turbine to the generator shaft

sea breeze

a wind that blows from the ocean to land during the day, caused by different cooling rates of water and land surfaces

secondary energy source

often called an energy carrier, secondary energy sources requires another source, like coal, to be converted for creation; electricity and hydrogen are examples

siting

the process of choosing a location for a wind turbine or farm

smart grid

computer-based remote control and automated system for electricity delivery that includes two-way interaction between the generation facilities, utilities, and consumers

sonar

sound navigation and ranging, using sound waves to measure distances, “see” underwater, and detect or communicate with objects under water

48

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

sound energy

energy that travels in longitudinal waves

static electricity

a stationary electric charge on a surface

substation

part of the electricity transmission grid where voltages are stepped down before the power is distributed to a neighborhood or community

thermal energy

internal energy within substances, movement or vibration of molecules

torque

the tendency of a force to rotate an object about its axis or pivot, a twist

tower

structural support of the turbine

transformer

a device that changes the voltage of electricity

transmission

the movement or transfer of electricity via power lines

transmission line

power lines that carry electricity at higher voltages long distances

turbine

a machine of blades that converts kinetic energy of a moving fluid to mechanical power

turbulence

an irregular motion within a moving fluid

voltage

a measure of the pressure (or potential difference) under which electricity flows through a circuit

wake

behind a wind turbine that is slower moving and less smooth due to the energy that was extracted by the turbine

watt

unit of measurement of electric power

wind

moving air created by uneven heating of Earth’s surface

wind shear

a change in wind speed and/or direction along a straight line or within a short distance

wind turbine

a system that converts motion energy from the wind into electrical energy

wind vane

an instrument used to show the direction of the wind

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

49

50

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

NEED’s Online Resources NEED’S SMUGMUG GALLERY

SOCIAL MEDIA

http://need-media.smugmug.com/ On NEED’s SmugMug page, you’ll find pictures of NEED students learning and teaching about energy.

Would you like to submit images or videos to NEED’s gallery?

E-mail info@NEED.org for more information. Also use SmugMug to find these visual resources:

Online Graphics Library Would you like to use NEED’s graphics in your own classroom presentations, or allow students to use them in their presentations? Download graphics for easy use in your classroom.

Stay up-to-date with NEED. “Like” us on Facebook! Search for The NEED Project, and check out all we’ve got going on!

Follow us on Twitter. We share the latest energy news from around the country, @NEED_Project.

Follow us on Instagram and check out the photos taken at NEED events, instagram.com/theneedproject.

Follow us on Pinterest and pin ideas to use in your classroom, Pinterest.com/NeedProject.

Subscribe to our YouTube channel! www.youtube.com/user/NEEDproject

AWESOME EXTRAS

NEED Energy Booklist

Looking for more resources? Our Awesome Extras page contains PowerPoint presentations, helpful energy sites, and other great resources to compliment what you are teaching in your classroom!

This page is available under the Educators tab at www.NEED.org/ educators/awesome-extras/.

Looking for cross-curricular connections, or extra background reading for your students? NEED’s booklist provides an extensive list of fiction and nonfiction titles for all grade levels to support energy units in the science, social studies, or language arts setting. Check it out at www.NEED.org/booklist/.

The Blog

U.S. Energy Geography

We feature new curriculum, teacher news, upcoming programs, and exciting resources regularly. To read the latest from the NEED network, visit www.NEED.org/about-need/news/.

Evaluations and Assessment

Maps are a great way for students to visualize the energy picture in the United States. This set of maps will support your energy discussion and multi-disciplinary energy activities. Go to www.need.org/resources/ energy-in-society to see energy production, consumption, and reserves all over the country!

Building an assessment? Searching for standards? Check out our Evaluations page for a question bank, NEED’s Energy Polls, sample rubrics, links to standards alignment, and more at www.NEED.org/educators/evaluations-assessment/.

E-Publications The NEED Project offers e-publication versions of various guides for in-classroom use. Guides that are currently available as an e-publication can be found at www.issuu.com/theneedproject.

©2021 The NEED Project

Exploring Offshore Wind Energy

www.NEED.org

51

National Sponsors and Partners Adapt2 Solutions Alaska Electric Light & Power Company American Electric Power Foundation American Fuel & Petrochemical Manufacturers Arizona Sustainability Alliance Armstrong Energy Corporation Robert L. Bayless, Producer, LLC Baltimore Gas & Electric Berkshire Gas - Avangrid BG Group/Shell BP America Inc. Blue Grass Energy Bob Moran Charitable Giving Fund Boys and Girls Club of Carson (CA) Buckeye Supplies Cape Light Compact–Massachusetts Central Alabama Electric Cooperative CLEAResult Clover Park School District Clovis Unified School District Colonial Pipeline ComEd Confluence ConocoPhillips Constellation Delmarva Power Dominion Energy, Inc. Dominion Energy Charitable Foundation DonorsChoose Duke Energy Duke Energy Foundation East Baton Rouge Parish Schools East Kentucky Power EcoCentricNow EDP Renewables EduCon Educational Consulting Enel Green Power North America Eugene Water and Electric Board Eversource Exelon Exelon Foundation Exelon Generation Foundation for Environmental Education FPL The Franklin Institute George Mason University – Environmental Science and Policy Georgia Power Gerald Harrington, Geologist Government of Thailand–Energy Ministry Green Power EMC Greenwired, Inc.

©2021 The NEED Project

Guilford County Schools–North Carolina Honeywell Houston LULAC National Education Service Centers Iowa Governor’s STEM Advisory Council Scale Up Illinois Clean Energy Community Foundation Illinois International Brotherhood of Electrical Workers Renewable Energy Fund Illinois Institute of Technology Independent Petroleum Association of New Mexico Jackson Energy James Madison University Kansas Corporation Energy Commission Kansas Energy Program – K-State Engineering Extension Kentucky Office of Energy Policy Kentucky Environmental Education Council Kentucky Power–An AEP Company League of United Latin American Citizens – National Educational Service Centers Leidos LES – Lincoln Electric System Liberty Utilities Linn County Rural Electric Cooperative Llano Land and Exploration Louisiana State Energy Office Louisiana State University – Agricultural Center Mercedes-Benz USA Minneapolis Public Schools Mississippi Development Authority–Energy Division Motus Experiential National Fuel National Grid National Hydropower Association National Ocean Industries Association National Renewable Energy Laboratory NC Green Power Nebraskans for Solar NextEra Energy Resources Nicor Gas NCi – Northeast Construction North Shore Gas Offshore Technology Conference Ohio Energy Project Oklahoma Gas and Electric Energy Corporation Omaha Public Power District Pacific Gas and Electric Company PECO Peoples Gas

8408 Kao Circle, Manassas, VA 20110

1.800.875.5029

www.NEED.org

Pepco Performance Services, Inc. Permian Basin Petroleum Museum Phillips 66 PNM PowerSouth Energy Cooperative Providence Public Schools Quarto Publishing Group Prince George’s County Office of Sustainable Energy (MD) Renewable Energy Alaska Project Rhoades Energy Rhode Island Office of Energy Resources Rhode Island Energy Efficiency and Resource Management Council Salal Foundation/Salal Credit Union Salt River Project Salt River Rural Electric Cooperative C.T. Seaver Trust Secure Futures, LLC Shell Shell Carson Shell Chemical Shell Deer Park Singapore Ministry of Education SMECO SMUD Society of Petroleum Engineers South Carolina Energy Office SunTribe Solar Tri-State Generation and Transmission TXU Energy United Way of Greater Philadelphia and Southern New Jersey Unitil University of Kentucky University of Louisville University of Maine University of North Carolina University of Rhode Island University of Tennessee University of Texas Permian Basin University of Wisconsin – Platteville U.S. Department of Energy U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy U.S. Department of Energy - Water Power Technologies Office U.S. Department of Energy–Wind for Schools U.S. Energy Information Administration United States Virgin Islands Energy Office We Care Solar