Quiz

The Student Guide and Science of Wind – Starter Pack contain the quiz.
Answer Key: Q1:B Q2:B Q3:A Q4:B

Reading and Extended Reading

The Student Guide contains the Science of Wind – Reading and Extended Reading info sheets.

Reading Answer Key

1. The Sun heats parts of the Earth differently.
2. Sails for boats or grinding grain with windmills.
3. The blades spin and make electricity.
4. Over 300 feet.
5. A group of turbines that make electricity.
6. In oceans or big lakes.
7. It doesn’t pollute the air or water.
8. They can hurt birds and bats.
9. Fiberglass or other strong materials.
10. 20 to 25 years.

Extended Reading Answer Key

1. Uneven heating of Earth’s surface causes wind
2. Sailing ships and grinding grain with windmills.
3. Blades, tower, nacelle.
4. 6-9 miles per hour.
5. Blades spin a rotor connected to a generator.
6. Stronger, more consistent wind and fewer people nearby.
7. No pollution, no fuel needed.
8. Bird and bat collisions, noise, visual impact.
9. Careful siting and better turbine design.
10. Wind speed, access to power lines, public acceptance.
11. Texas, Iowa, Oklahoma.
12. Steel, concrete, fiberglass, carbon fiber.
13. 20-25 years.
14. Made of hard-to-recycle composite materials.
15. Researching recyclable blade materials.

1. Possible Answer: Wind energy produces electricity without emitting greenhouse gases, unlike fossil fuels, which release carbon dioxide and other emissions that impact the environment. Wind turbines also use no water for operation, whereas natural gas, and coal plants often require significant water resources. However, wind energy has trade-offs, such as the impact on birds and bats, noise, and the visual effect on landscapes. Additionally, manufacturing turbines requires materials and energy, and recycling turbine blades remains a challenge. Overall, wind energy has a smaller environmental footprint than fossil fuels, but it is not impact-free.
2. Possible Answer: Many students might argue yes, the benefits outweigh the costs, because offshore wind farms produce more consistent and powerful energy due to steady ocean winds, and they can be placed far from populated areas, reducing land use conflicts. They also contribute to reducing greenhouse gas emissions. On the other hand, the costs are higher due to construction challenges, maintenance difficulties, and environmental impacts on marine life. Whether the benefits outweigh the costs depends on how well these challenges are managed and the value society places on clean, renewable energy.
3. Possible Answer: Communities and companies should prioritize repowering existing turbines by upgrading parts or installing newer, more efficient models. Recyclable materials like steel and copper should be recovered and reused. Efforts should also be made to develop and adopt recyclable blade materials. Disposal methods should follow environmental regulations to avoid landfilling non-recyclable components whenever possible. Planning ahead for decommissioning and including sustainability goals in project planning can help reduce costs and environmental harm over the long term.

Computation

The Student Guide contains the Science of Wind – Computation activity.
Answer Key: Q1: (2304.44 – 345.92) / 13 = 150.66 TWh/year
Q2: 2020-2021 saw the largest increase of 258.79 TWh. Q3: (2304.44 / 29,429.05) = 0.783 = 7.83%
Q4: 2304.44 + (2 x 150.66) = 2605.76 TWh
Q5: (Answers will vary) Example: Falling costs of wind technology, government policies and subsidies, technological advancements, environmental concerns, energy security.

Data Set

The Student Guide contains the Science of Wind – Data Set.
Answer Key: Question 1: In the late afternoon/early evening (5 PM – 7 PM). This could be because people are returning home from work or school and turning on appliances, lights, electronics, etc. It’s also one of the hottest parts of the day, increasing cooling needs.
Question 2: No. Wind output is higher in the early morning hours and lower during the afternoon and evening, which is when electricity demand peaks.
Question 3: (Answers will vary) Example: Turbines can only generate near capacity when wind speeds are optimal; the wind may simply not be strong enough.
Question 4: (Answers will vary) Example: Geography and availability of water resources; cost of installation; fuel access; environmental impact.
Question 5: (Answers will vary) Example: Energy storage systems; complementary energy systems.

Lab Investigation: Wind Energy

The Student Guide contains the Lab Investigation: Wind Energy – Student activities and questions.

Answer Key for Part 1 (Analyzing the Wind Power Formula)

Answers A-E: Many factors could be identified including: wind speed, temperature, humidity, air density, turbine height, blade length, turbine location, obstacles near turbines, turbine efficiency, etc. 
F. The symbol ρ represents air density.
G. Factors affecting air density include altitude, atmospheric pressure, temperature, and humidity. 
H. If air density increases, then wind power increases. 
I. Given the equation, there is a direct relationship between wind power and air density. 
J. A stands for the area of the circle that the turbine blades move through. 
K. The formula for this area is A = πr²
L. The variable v in the equation represents the wind velocity and should be measured in units of m/s. 
M. Wind velocity is measured using an anemometer. 

Answer Key for Part 2 (Building an Anemometer and Calibration):

A. Low Fan Setting Data Table

B. Medium Fan Setting Data Table

C. High Fan Setting Data Table

D. Measure the diameter of your anemometer’s circular path (cm)
Sample data: 17 cm 
E. The distance per revolution (cm) can be found with the following formula: π x diameter (Note: You may use 3.14 for π)
Sample Calculation: Distance per revolution = π (17 cm) = 53.4 cm/revolution

F. Low Fan Setting Calculations Table (Sample Calculation)

G. Medium Fan Setting Calculations Table (Sample Calculation)

H. High Fan Setting Calculations Table (Sample Calculation)

Answer Key for Part 3 (Simulated Windmill Sample Calculations):

A. Month: July
B. Average Temperature: 85.5 ^oF 
C. Average Humidity: 69% 
D. Average Air Pressure: 29.54 in of Mercury
E. Altitude: 489 feet above sea level 

F. Wind Turbine Survey Data Table (Sample Data)

G. Wind Power Calculations Table (Sample Calculation)

H. 366 W x (0.4) = 146 W 
I. Answers will vary.
J. Even small changes to wind speed will have a significant effect on the overall power output. This will occur because in the wind power equation, the velocity is cubed, thus having a big impact. 
K. The power output drops to zero. This occurs because the wind turbine must be shut down and rotation stopped to prevent damage to the equipment. 
L. At wind speeds of 40 km/hr, the expected output is roughly 0.7-0.8 MW. The best site would be one that has winds consistently at, or near, the rated speed to ensure maximum performance. 
M. The graph shows an exponential increase up to the rated speed, demonstrating that slower than optimal wind speeds have a much lower output. It also shows that very high wind speeds also result in no power being produced. 
N. Answers will vary but may include: acceptance of local stakeholders (due to sight, noise, etc of turbines), migratory patterns of birds, distance from the grid and other transmission lines, accessibility for maintenance, zoning laws, cost of installation and maintenance, weather extremes in the area, etc. 
O. Answers will vary but students may have inconsistencies in counting the number of revolutions of the rotating anemometer as it can be particularly difficult to count at higher wind speeds. This would certainly affect the accuracy of the results.
Note: To compare, students could apply the wind power equation using some theoretical wind speeds (e.g. 20 – 40 miles/hour or 9-18 m/s) to obtain more accurate values.