Modular Off-Grid Hydroponics - STEM Pre-Academy …stempreacademy.hawaii.edu/sites/default/files/modular-off... · Web view2016 2016 2016 Lesson Plan Modular Off-Grid Hydroponics

2016

Modular Off-Grid Hydroponics

Lesson Plan

ContentsI / Teacher Summary.......................................................................................................................................................2

1. Lesson Focus........................................................................................................................................................2

2. Grade Level..........................................................................................................................................................2

3. Objectives............................................................................................................................................................2

4. Project activities...................................................................................................................................................2

5. Alignment to Curriculum Frameworks.................................................................................................................2

6. Resources/Materials............................................................................................................................................2

II / General protocol – For Teachers................................................................................................................................2

1) Procedure............................................................................................................................................................2

2) Time Needed.......................................................................................................................................................3

3) Materials.............................................................................................................................................................3

4) Preliminary Setup Procedure...............................................................................................................................3

5) Additional notes..................................................................................................................................................5

III / Student Worksheet...................................................................................................................................................6

1) Engineering Design Process.................................................................................................................................6

2) Experiment........................................................................................................................................................10

Appendix: Alignment to HCPSIII and NGSS....................................................................................................................23

1

I / Teacher Summary

1. Lesson FocusHydroponic agricultural methods have been around for some time. Many designs include components which require electrical power, like pumps. Photovoltaics are a renewable source of electrical energy generation. Engineers have been challenged to come up with better ways to create models for sustainable agriculture. The combination of photovoltaics and powered hydroponics has been suggested as a model for sustainable agriculture.

2. Grade Level Grades 6-8

3. Objectives Explore the engineering design process and its application to combining off-grid photovoltaic

generation to hydroponic agriculture. Conduct a scientific inquiry into the effects of various growing media on plant growth in a

hydroponic garden.

4. Project activities Participate in building a hydroponic garden powered by a photovoltaic array. Measure and calculate energy usage by system components. Compare the efficacy of various growing media using the scientific method. Explore engineering design process.

5. Alignment to Curriculum Frameworks See appendix.

6. Resources/Materials Teacher resources Student worksheet Appendix

II / General protocol – For Teachers

1) Procedure1. Have students read the introduction to hydroponics in class or for homework.2. Divide the students into groups, each can be responsible for one plant pot and one growing

media. Each student can have and fill out their own student worksheet for data.3. Start with the engineering design process for powering a hydroponics kit using photovoltaics.

You want to lead them to the design that you already have the parts to build. This can be a demonstration of the engineering design process without carrying out all of the steps in detail. You can develop ideas in the classroom up until the create step:

o Problem Statement: How would we use photovoltaics to power a hydroponics system?o Ask: Explore the key questions which need to be answered in order to start to design.o Imagine: Begin to brainstorm ideas and imagine a design.o Create: You will build the system.o Improve: Develop ideas about how the system could be improved further. (e.g. using

panels for water catchment, etc.)

2

4. Start scientific method for hydroponic experiment. Ask students to make a hypothesis about whether they feel that hydroponic gardening or growing in soil will grow plants faster.

5. Build the photovoltaic and hydroponic systems with the class and plant plants.6. Record data in worksheet and make conclusions.

2) Time Needed 2-3 forty-five minute class periods 5-10 minutes of data gathering at regular intervals for two weeks. Recommended frequency 2-3

days.

3) Materials Hydroponic garden kit (grow tray, rolling tray stand, water tank, pumps, the nutrients, growing

material) Agricultural grade shaded tarp Filtered water Measuring cup Gloves Planting pots Hand trowel or scoop Starter seedlings Lab notebook Ruler with millimeter markings Scale pH paper / pH meter Thermometer Off-Grid Photovoltaic Generation kit Kill-A-Watt power meter

4) Preliminary Setup ProcedureBefore having the class begin to participate, you must make some preliminary preparations such as finding an adequate location.

1. Site considerationsChoose an adequate site location which may include considerations such as:

Security – vandalism and theft Sunlight – minimal shading by trees and buildings Access – how far is it from your classroom Wind – strong wind may damage equipment

2. Solar panel mounting surfaceTo mount the photovoltaic array you must find a surface which is securely fastened to resist wind currents and on which you are able to bolt the panels down on. A suggestion for a mounting surface is ¾” plywood. Figure 1 shows a picture of a ¾” plywood supported by CMU concrete tiles. To prevent the wind from disturbing the array, this installation uses nylon straps secured to the CMU blocks as shown in Figure 2. Mount and bolt the solar panels to the mounting surface ahead of time. You can demonstrate connecting the panels and equipment with your classroom if so desired.

3

Figure 1: Photovoltaic mounting surface.

Figure 2: Solar panels securely bolted to plywood surface.

4

3. Starter seedlingsIn order to see significant results within a short time, you should choose appropriate plants and get them started growing at least one and a half weeks in advance. An alternative is to order starter seedlings from your hydroponics supply. A suggestion for starting seedlings is to use the indoor kit designed for this purpose with a growing lamp as shown in Figure 3. Suggested plant types are lettuce, beans, or cherry tomatoes. The larger the seed, the larger you need to make the hole to plant it in to give it space to grow.

Figure 3: Starter seedlings grown indoors under growing lamp.

5) Additional notes The experimental protocol is covered in detail in the student worksheet section. Adjustments to pH and nutrient levels may need to be made on a regular basis dependent upon

the weather conditions, i.e. excessive rain (dilution), excessive heat (evaporation). For users with more experience with hydroponics systems the experiment can be easily

modified to test the effect of various growing media on hydroponic plant growth. Due to different aeration requirements of the varied growing media you would need to allow for two different flood trays with different timer settings. For modifications you would need to replace the 2 x 4 flood tray with two 2 x 2 flood trays, Figure 4, and add an additional timer and pump for the other tray. You could use perlite and clay pebbles (timing one for less absorbent material) in one tray and Rockwool and coconut husk (timing two for more absorbent material) in the other.

Figure 4: 2 x 2 flood tray, rochwool, and coconut husk growing media.

5

III / Student Worksheet

1) Engineering Design ProcessScenario:The President of the Energy Agency has given you a mission to figure out how to power a hydroponic gardening system in a location where there is no access to plugs. The components for the hydroponic garden system are already determined.

In class brainstorm how you would come up with a solution to this problem using photovoltaics. You do not need to come up with a specific solution, just use the following procedure to demonstrate the method you would take to get there.

ASK:1. Summarize the problem the client wants you to solve.

2. Identify the specific details needed to get a good solution (Specification Chart)

3. What (constraints) limits have been given to you?

Problem Statement:

One of the most important questions to ask in this scenario is: How much energy does my photovoltaic system need to provide? Perform the following procedure to determine your energy requirements.

Place the circulation pump into a small bucket of water. Plug the Kill-A-Watt power meter into the wall outlet and plug the pump into it to measure the power of the system. Using the measurements obtained, estimate the total energy usage for the 2 week duration of the experiment. We will be comparing this number to the measured value later.

Figure 5: Kill-A-Watt power meter.

6

Power in watts:_______________________________________________

Power factor (efficiency): _______________________________________

Time on per hour in percent : ______________

estimated energyusage=Watts×%timeon×24hours×14dayspower factor

*see procedure section (2)(j) for details about timer periods

%timeon=¿ of minutes on per hour60minutes

×100%

Estimated energy usage (Watt hours): ______________________________

Date and time of hydroponic start:

Time: ____________________ Date:_____________________________

Planned duration:___________days

Date and time of hydroponic end:

Time: ____________________ Date:_____________________________

IMAGINE:1. Brainstorm ideas. What are some solutions?

2. Consider what kind of resources and materials do you have?

3. What are your constraints?

4. What are the requirements?

5. Ask Questions.

7

PLAN:A pre-engineered system design is laid out to be built in the next section. See if you can come up with your own system design. You don’t need to provide values for your component ratings. Just come up with a general idea of what your system might look like.

Design

Materials

CREATE:You will follow the procedure in the Section 2 to create the system laid out there.

8

IMPROVE:After you have completed the experiment, come up with ideas on how you might improve your design.

After the full duration of the experiment, read the energy meter from the solar equipment panel, Figure 6. Is this value consistent with the value you calculated above?

Estimated energy usage from previous step (watt hours):____________________

Energy actually used from meter (watt hours): ______________________

Imagine that you had designed your system for exactly the amount of energy that you estimated in the ASK step. How would your design change based on the findings of your result.

Figure 6: Energy meter.

Write down your ideas about how to improve the design below.

9

2) Experiment1) Purpose

In this experiment, we will build a hydroponics system which runs on off-grid photovoltaic power and compare the growth of plants grown hydroponically to those grown in soil. To do so, we will compare the number of leaves, color of leaves, size of the leaves, and the weight after 2 weeks.

2) HypothesisIn class, you have been introduced to some information about the differences between plants grown hydroponically to those grown in soil. Using what you know, make a hypothesis about which method for growing plants will grow taller heavier plants in the same amount of growing time. Be sure to include why you believe this to be true. Try to back up your arguments using information you have learned in class. You can supplement this information with sources from the library or the internet. Be sure to make note of your information source.

Use the space provided below to write your hypothesis:

I believe that the _______________________ method for growing plants will grow taller heavier plants in the same amount of growing time.

I believe this because:

10

3) Procedure1) Photovoltaic generation system. Figure 7 shows how various components will be

connected.

Figure 7: Components of photovoltaic generation system.

a. Using the MC-4 wye connectors, connect the photovoltaic panels in parallel configuration. Figure 8 shows the male and female MC-4 wye connectors. Figure 9 shows a wiring diagram of how you would use these wye connectors to connect your panels in parallel. Each panel has two leads, one positive and one negative. These leads will have a female connector for the negative leads and a male connector for the positive leads. You will be connecting all of the panels negative leads together into one output and all of the panels positive leads together into one output. Be careful to never connect the panels negative and positive leads together. This will cause a short circuit.

Figure 8: MC-4 Wye Connectors

11

Figure 9: Parallel panel connection.

Figure 10 shows the leads from two separate solar panels. This is a total of four connectors. One wye connector will connect the two male plugs together (positive) and one wye connector will connect the two female plugs together (female) Figure 11.

Figure 10: Connectors from solar panels.

12

Figure 11: Male wye connector to female panel connectors.

Make sure to connect the panel side connectors into the double sided end of the MC-4 adaptors. There is a female MC-4 adaptor and a male MC4 adaptor. These connections can be seen in Figure 12.

Figure 12: Wye adaptors connected for parallel panel connection.

b. Connect the wire from the charge controller/inverter module labeled panels to the wye connections from the solar array as shown in Figure 13.

13

Figure 13: Inverter/charge controller connection to panels.

c. The charge controller/inverter panel is a clear plexiglass sheet with the components marked on it, . The panels will be connected to the wire entering the fuse in the upper right hand corner of the device layout.

Figure 14: Charge controller/inverter panel.

14

d. Connect the wires coming from the other fuse labeled battery, to the battery box connectors, .

Figure 15: Battery box connection.

e. Place the battery box into the larger container, connect the surge protector to the inverter, and plug the timer into the surge protector. Arrange the components into the protective box as shown in Figure 16.

Figure 16: Component container arrangement.

f. You are now ready to begin setting up the hydroponics system.

15

2) Hydroponics set upa. Assemble the flood tray stand as directed by the instructions including the light

hanger attachment. You will use this to install the shade material for the plants (not shown in figure). Place the 50 gallon reservoir beneath the flood tray Figure 17.

Figure 17: Flood tray stand and reservoir.

b. Fill the reservoir with water and attach the pump and drain hoses to the appropriate fittings on the flood tray.

c. Plug the pump into the timer and turn the system on to find the level of the water while the pump is active Figure 17.

d. Cut a sheet of black and white poly-film to the size of the flood tray and attach using Velcro leaving the white side up. Figure 18 shows the black and white loly installed, you will add the pots in a later step. This will help to prevent evaporation and moderate the temperature.

e. When cutting slots for each pot, the spacing can be closer or further than is shown in Figure 18. It is based on your preference.

Figure 18: Poly-film installed onto flood tray.

16

f. It is now time to add plants. Each group of students will be assigned a plant starter Figure 19. Each group will be responsible for transplanting, and collecting data about their plant. Half of the plants will be grown hydroponically and half will be grown in soil.

Figure 19: Plant starters.

g. For the groups assigned to growing plants in soil, transplant your entire block of Rockwool into a regular soil pot and fill the pot with soil around the Rockwool block. Backfill the pot slightly to raise the Rockwool from the bottom of the pot and fill the remaining space with soil. The soil should be high enough to just cover the top of the Rockwool. Do not compact the soil heavily. You will place the pots next to the hydroponic system to grow under the same sunlight conditions.

h. For groups assigned to grow their plants hydroponically, transplant your plant starter by placing the entire Rockwool block into the net pot and filling the rest of the pot with clay pebble growing media. Be careful to place your plant at a height where the entire root system will be fully submerged and touching at least the bottom of the Rockwool block when the water level in the flood tray is at its maximum height. Figure 20 shows a freshly transplanted starter in clay pebbles.

Figure 20: Transplanted starters.

i. Record initial data about your groups plants in the data section of this worksheet.j. Cut X shaped slits into the poly film to insert your pots and arrange them neatly into

the flood tray as shown in Figure 18.

17

k. Set the timer as directed by the instructions included with it to regular intervals. The suggested flood time is 15 minutes every hour for the clay pebble growing media. It may need to be adjusted to 15 minutes on and then 15 minutes off continuously during hot noon times, such as 10am to 3pm. Remember, depending how you set this interval will affect your energy calculation in the engineering design process section of this activity.

l. Drape the shade cloth over the flood tray assembly using the light hanger attachment for the rolling tray stand and secure the bottom Figure 21.

Figure 21: Shade cloth drape.

m. Add nutrient to the 25 gallon reservoir according to the directions on the package.n. Test the total dissolved solids (TDS) level using the TDS meter shown in Figure 22.

The TDS reading should be between 500 and 1000. Adjust by adding nutrient (up) or water (down) to the reservoir. For seedling, the TDS should be between 500 to 600. With lettuce and cherry tomatoes, the max TDS should be about 750. Then for flowering plants it can be closer to 1000 TDS. Over time the TDS can be gradually increased ever couple of weeks.

Figure 22: TDS (below) and pH (above) meters.

o. Test the pH using the pH meter. Adjust the pH using the pH adjustment kit to the appropriate level between 6.0 and 6.5.

p. Record these values in the data section of this worksheet.

18

3) Data collectiona. Take measurements of your plants every 2-3 days for a two week period and record

the values in the data section of this worksheet.i. Record plant height.ii. Measure pH and TDS and adjust when necessary to bring back to the

appropriate range as indicated in the previous section. Be sure to top off the reservoir with water, measure again, and then adjust the pH and TDS, in that order. Record the values after adjustment. These values may be important if something goes wrong with your experiment to explain why for example the plants died unexpectedly.

iii. Monitor the energy usage. If there is a large discrepancy between the estimated energy usage and the actual energy usage, you can look at your data and see if there is a time when something changed. This might be something like a timer malfunction and it was locked in the on position. You would see a sudden jump in energy consumption at a certain point.

iv. After two weeks time, take note of the total electrical energy used by the system and record the data for use in the engineering design process section of this worksheet above.

b. Make a graph of your plant height data.c. Make a graph of the energy consumption.d. Remove your plant from the growing media or soil, then remove the Rockwool and

record the weight in the data section. Try to rinse and dry the roots as much as possible to avoid including water weight in your result.

e. Compare the different groups’ data to draw conclusions about the efficacy of hydroponic gardening compared to gardening in soil.

19

4) Data and Results

Group/Pot Number:_________________

Plant type: ________________ Growing method: Hydroponic Soil

Start date:______________________ Start time:______________________

Date Plant Height (in) pH TDS (ppm) Energy usage (wh)

Plant Height vs Time

Fill in the chart data on the graph paper provided above. Be sure to label your axes appropriately with the date on the x-axis and plant height on the y-axis.

20

Energy Usage vs Time

Fill in the chart data on the graph paper provided above. Be sure to label your axes appropriately with the date on the x-axis and energy usage on the y-axis.

Measure the final weight of your plant:

End date: _______________________ End time:________________

Weight:____________________________

Share your data with the other groups and record your results in the tables below.

Hydroponic:

Group Plant Type Final Plant Height (in) Final Plant Weight (g)

Soil:

Group Plant Type Final Plant Height (in) Final Plant Weight (g)

21

5) ConclusionsBased upon your collective group data what can you conclude about hydroponic gardening compared to growing plants in soil? Make sure to explain why you are making this conclusion. Be certain that you mention your data in your explanation:

Has your hypothesis been confirmed or disproven? If it was disproven, explain why you think your hypothesis may not match your results.

Do you think you could do further experiments to refine your discoveries or to improve upon your knowledge about hydroponic plant growth based on your experience? Explain what types of tests you might want to do below.

22

Appendix: Alignment to HCPSIII and NGSS

HCPSIII

SC.8.1.2 Communicate the significant components of the experimental design and results of a scientific investigation

 Standard 3Life and Environmental Sciences: ORGANISMS AND THE ENVIRONMENT:

Understand the unity, diversity, and interrelationships of organisms, including their relationship to cycles of matter and energy in the environment

 Standard 4Life and Environmental Sciences: STRUCTURE AND FUNCTION IN

ORGANISMS: Understand the structures and functions of living organisms and how organisms can be compared scientifically

SC.8.8.4 Explain how the sun is the major source of energy influencing climateand weather on Earth

NGSS

  MS-PS3 Energy

MS-LS1-5 Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms

 MS-LS1-6Construct a scientific explanation based on evidence for the role of photosynthesis

in the cycling of matter andflow of energy into and out of organisms

 LS1.C Organization for Matter and Energy Flow inOrganisms

 PS3.D Energy in Chemical Processes and EverydayLife

 MS-ESS3 Earth and Human Activity

 MS-ETS1 Engineering Design

23