Ag & Energy - Lesson 6 - Agriculture & Wind Energy

Ag & Energy - Lesson 6 - Agriculture & Wind Energy

Target Grade Level / Age Range:

Grades 9-12

Time:

90 minutes

Purpose:

By the end of this lesson, students will be able to:

  1. Understand that there are different types of power that can be harnessed from the wind.
  2. Understand the benefits and limitations of wind power.
  3. Identify the characteristics that make for a good wind energy generation site.

Materials:

  • Hair dryer
  • Brown lunch bags
  • Straws
  • Craft sticks
  • Different kinds and weights of paper
  • Rulers
  • Tape
  • Glue
  • Paperclips
  • Binder clips
  • Index cards
  • Pencils
  • String
  • Scissors
  • Paper or plastic cup
  • Weights (gram weights or pennies)

Suggested Companion Resources

Vocabulary

  • Wind: flow of gases created by the Earth’s rotation and the movement of air between hot and cold spots on the Earth
  • Wind power: the force of winds blowing across the earth’s surface
  • Wind energy: the power transfer from harnessing the kinetic energy of the wind

Background – Agricultural Connections

Humans first harnessed the wind over 7,000 years ago to navigate the Nile River. Today, wind technology produces over 250 GW of electricity a year and helps farms with remote power needs and sustainability efforts. 250 GW (gigawatts) is the approximate annual global production of wind power.

Interest Approach or Motivator

As students enter the classroom have them watch the brief video on wind turbines https://youtu.be/YzgWUzTKYIs.

What is one thing that surprised them about wind turbines or wind energy?

Procedures

Objective 1: Understand that there are different types of power that can be harnessed from the wind.   
  1. Mechanical Wind Power: Wind turbines convert the kinetic energy of the wind into mechanical power. This mechanical power can be used directly to pump water, mill grain or otherwise drive a gearbox.
    1. Livestock watering tanks in remote areas
    2. Irrigation systems
    3. Field drainage systems
  2. Electrical Wind Power: Wind rotates blades by force and by creating low pressure on the backside like an airplane wing. Blade rotation is “geared up”. Spinning shaft drives generator creating electricity. Power is sent down tower for direct use or into electric grid.
    1. Small-scale (under 100 kW) can provide all or part of residential & farm energy needs.
    2. Commercial-scale now reach 500 feet and can produce 7 MW (7,000 kilowatts)!

Divide the students into four groups. Two groups will do activity 1 and design a wind mill to harness mechanical power. Two groups will do activity 2 and design a wind mill to harness electrical power. Create four brown bags filled with the various supplies for creating a wind mill. Give one bag to each group. Give teams 30 minutes to design and test their windmills.

Activity 1: With students working in collaborative groups, each group will design a windmill that will generate the most energy (aka harnesses the most air and therefore rotates the fastest).   Students can experiment with the size and also the shape of the windmill blades.  To challenge the students, require that the total area of each blade cannot exceed 4 square inches. 

As students work through the design process, they will not need to design a foundation for their windmills.  While students are in the building process, they will need to mark one blade to make it easy to count revolutions when placed in front of the fan.  When it is time to test, each team can either hold their windmill or use a large binder clip to affix it to the back of a chair.  Windmills should be placed 60cm away from the fan set on high.

Once everything is in place, students can count the number of revolutions the blades make in one minute.  Students can redesign their windmills twice, each time testing and hopefully increasing the number of blade revolutions each time.  With their final design, teams will compete against each other to see which windmill blades completes the most revolutions in 2 minutes.

Activity 2: The main difference in design is that turbines producing electricity need to spin fast so have fewer (typically three), thinner blades. Those that harness wind power to drive machinery, such as water pumps and windmills, need a higher torque and to be more stable. They generally have a higher number of larger blades.

With students working collaboratively in groups, each group will design a windmill that will generate enough torque to raise a cup attached to a string. Students can experiment with the size and shape of the windmill blades.

As students work through the design process, they will need to design a foundation for their windmills (attached to a table would work best). When it is time to test, each team will use the hair dryer fan to power their windmill. Hold the hair dryer 10cm away set on high. Challenge students to see whose windmill can lift the most weight. Use pennies or gram weights to weigh down the cups. Students can redesign their windmills twice, each time testing and hopefully increasing the amount of weight that can be lifted. With their final design, teams will compete to determine which can lift the most weight.

Possible solution for wind power challenge:

Objective 2: Understand the benefits and limitations of wind power.

In their notebooks, ask students to create two columns. Label one column as ‘pro’ and the other column as ‘con’. As you go through the next set of notes on slides 5-10, have students capture classify the notes in either the pro or con column in their notebooks.

  1. Economies of Scale: The average installed cost of a small-scale turbine in the U.S. is $3,000-5,000 per kW, which is 2½ times the cost of large turbines (per watt). But with tax credits, rebates and utility purchase agreements, small turbine owners can pay for their system within 10 years, then enjoy FREE POWER!
  2. Rural Economic Benefits: Iowa’s 240 MW of wind energy has produced the following economic benefits:
    1. $640,000/yr in lease payments to farmers (approx. $2,000/turbine/yr)
    2. $2 million/yr in property taxes
    3. $5.5 mil/yr in operations and maintenance income
    4. 40 long-term operations and maintenance jobs
    5. 200 short-term construction jobs
  3. Leasing and cooperative ownership: Farmers/landowners can lease their land for wind energy development or pursue collective ownership of their own turbine(s) through co-ops.
  4. Considerations
    1. Variability of Resource: the available wind powering turbines may change throughout the day and year.
    2. Limitations to Farming: include aerial crop-dusting and maneuvering large equipment in the field. 
    3. Noise/Strobe Effect/Aesthetics: Turbines do make noise and they are big and may disrupt views. Be sensitive to your neighbors. Talk to them during the planning process and find out their concerns. If possible, place your turbines where they will be least seen and heard by neighbors
    4. Environmental Impacts: Wind energy is non-polluting and therefore a good environmental choice. But any time we produce energy, we run the risk of disrupting ecosystems. Wind turbines are no different. They are not allowed in wetlands or other sensitive areas, and they also should not be located in migratory bird flyways because, like any large structure, they can kill birds. You may not want to place turbines in scenic areas where they will detract from the view.
    5. Polluting Manufacturing Process
    6. Fate of Towers Once Decommissioned
  5. Potential
    1. The amount of potential wind power worldwide is more than four times the total annual power consumption of the entire world (72 terawatts).

The amount of kinetic wind energy within Earth's atmosphere is equal to ~10,000 trillion kW-hours.

Objective 3: Identify the characteristics that make for a good wind energy generation site.

Present information in slides 11-15 and have students capture key ideas into their notebooks.

  1. Identify your wind resource: State energy potential (maps)
    1. http://apps2.eere.energy.gov/wind/windexchange/wind_maps.asp
    2. http://apps2.eere.energy.gov/wind/windexchange/windmaps/community_scale.asp
  2. Zoning:
    1. Residentially zoned areas often have a height limit of 35 feet.
    2. Any wind turbine is subject to local zoning laws.
    3. Some states also have requirements based on the size of electric generating facilities.
      1. For example, 25 MW or larger projects to be installed in Minnesota must receive a permit from the Public Utilities Commission which requires an environmental impact statement (EIS).
      2. State permits usually supersede local zoning laws.
      3. Federal Aviation Authority (FAA) must permit every structure over 200 feet tall that is near the airport or within flight paths.
  3. Site selection: Wind turbines are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more above ground, they can take advantage of faster and less turbulent wind. This also minimizes disturbance from obstacles such as buildings and trees.
  4. Estimate potential power: Power in the wind = ½ρAV3
    1. A = Effect of swept area (Swept Area: A = πR2 Area of the circle swept by the rotor (m2).
    2. V = Effect of wind speed
    3. r = Effect of air density
    4. Power is a cubic function of wind speed   V x V x V
    5. 20% increase in wind speed means 73% more power
    6. Doubling wind speed means 8 times more power!
  5. Ownership: Once you have determined that you have a strong wind resource and your property is suitable for development, you will want to decide what level of involvement in the project you are comfortable with. There are three basic ways to undertake wind energy development:
    1. Lease your land to a wind developer
    2. Join with others in investing
    3. Own the turbine(s) yourself
Review:

Use the student learning objectives to summarize the lesson. Review by playing a game of Jeopardy.

Prior to class the instructor should determine categories for questions. Suggestions include Mechanical Power, Electrical Power, Economies of Scale, Rural Economic Benefits, Etc. Using these, or other categories determined by the instructor, have students write facts from the lesson on 3x5 cards.

On a separate sheet of paper, have students write an appropriate question for each fact card created. Question writing primes students for the game. The instructor should then gather the fact cards by category and remove duplicates. Review the procedure for playing “Jeopardy” and make any modifications needed for your classroom. Finally, before playing, group students into teams.

Instructor should assist students in creating fact cards. Once students are finished creating fact cards, collect by category and review the procedure for playing Jeopardy.

Instructor will serve as the host and students will work in teams. All answers will be of equal value. Teams will gain control of the board by providing a correct question to an answer. Teams will ring in by having one person in the group raise their hand. Each person in the group must take a turn before another person can go a second time. Remember, you will respond with a question to each fact given.

As students provide answers to questions, take time to clear up any misunderstandings about the content. The instructor can keep score or groups can keep score. The instructor may wish to award a prize for the team with the most points at the end. The instructor can make the game more entertaining by taking on characteristics of the host. To determine which group goes first, have groups guess a number, flip a coin, or determine through “rock, paper, scissors”.

Worksheet Key:

  1. 1.225 x 3,923 x 343 x .5 = 824,173 W/m^2
  2. 1.225 x 3,923 x 512 x .5 = 1,230,252 W/m^2
  3. Answers will vary

Essential Files (maps, charts, pictures, or documents)

Extension Activities

  • Using the website www.windustry.org (and its various links) have students design a hypothetical wind project and identify available financial incentives for their region and chosen project.
  • Have students write their opinions on wind energy. Essays may focus on its effects on agriculture and/or applications for farms.

Sources/Credits

Author(s)

Will Fett

Organization Affiliation

Iowa Agriculture Literacy Foundation

Agriculture Literacy Outcomes

  • Theme 1: Ag & the Environment
    • Describe resource and conservation management practices used in agricultural systems (e.g., riparian management, rotational grazing, no till farming, crop and variety selection, wildlife management, timber harvesting techniques)
    • Discuss the value of agricultural land
    • Evaluate the various definitions of “sustainable agriculture,” considering population growth, carbon footprint, environmental systems, land and water resources, and economics
  • Theme 4: STEM
    • Identify current and emerging scientific discoveries and technologies and their possible use in agriculture (e.g., biotechnology, bio-chemical, mechanical, etc.)
    • Evaluate the benefits and concerns related to the application of technology to agricultural systems (e.g., biotechnology)

Education Content Standards

  • Mathematics – Modeling
  • HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.*

Common Core Connections

  • RI.9-10.IA.1: Employ the full range of research-based comprehension strategies, including making connections, determining importance, questioning, visualizing, making inferences, summarizing, and monitoring for comprehension.
  • RI.9–10.2: Determine a central idea of a text and analyze its development over the course of the text, including how it emerges and is shaped and refined by specific details; provide an objective summary of the text.