LESSON PLAN for SRDES Day 1

Name: Jason Avent

Title of lesson: Energy at the Source

Date of lesson: November

Length of lesson: 1 hour 50 minutes (one hour for lesson, 20 minutes for coating of DSSC glass with TiO₂)

Description of the class: Environmental Science for Upperclassmen

Name of course: SRDES

Grade level: 11/12

Honors or regular: Honors

Source of the lesson:

Lesson is built from information supplied with the Nanocrystalline Solar Cell Kit. In addition some solar power gizmos like a solar battery charger and an H₂ fuel cell car are found in the UTeach inventory.

TEKS addressed:

TEKS are not especially relevant for these students who are most likely performing at the mastery level. I am searching for a more elusive kind of learning that integrates the concepts and helps them understand the cycle and the back-and forth problems created by plants, their storage of energy, their needs for CO₂, and the greenhouse effect. For a Biology classroom, the TEKS expected to be addressed are listed here: TEKSBiology

I. I. Overview

Students should understand that all energy is solar-derived (except fission- and even Uranium was formed by the fusion reactions of a star). They should see that most forms of energy require some storage in matter in order to defer usage (CO₂ à carbohydrates; H₂O à H₂ + O₂; Battery discharged à charged ) Electricity without a battery must be used immediately or stored, and the conversion of energy from one form to another always comes with a loss of efficiency.

Students will be introduced to the carbon/water cycle as a battery used by plants to put energy into molecules that they use later through respiration. Plants have removed most CO₂ from the atmosphere while the sun was cooler. Now there is very little CO₂ and the sun is hotter, so everything was (seemingly) balanced until we released stored CO₂ from fossil fuel. Now the hotter sun and the increased greenhouse effect are heating the Earth and make life more precarious. Plants “appreciate” the additional CO₂ and still suffer from insufficient concentrations (photorespiration). How do we find a compromise between a cooler Earth and the continued growth of plants?

After some introduction to the topic and why they should be concerned, the students will perform the first step of the Dye Sensitized Solar Cell (DSSC) construction- the deposition of TiO₂ slurry onto the conductive glass plates. After coating the plates, the students will put them into a glass tube so that a hot air gun can sinter them.

II. Performance or learner outcomes

Students will be able to: explain the conflict between our needs for a cool planet, and the plant’s needs for more CO₂.

They will explain the loss of energy at each conversion from one form to the next (Second law of thermodynamics).

They will understand the compromise between efficient, immediate use of energy and inefficient but necessary storage. The number of conversions dramatically increases inefficiency of energy will be a key concept.

Students will understand that our energy is stored as chemistry of oxidation and then released when the oxidation is allowed to run “downhill” on an energy diagram much like water pumped uphill can be allowed to run down and supply energy to a water wheel.

III. Resources, materials and supplies needed

 H₂ fuel Cell Car

Silicon solar cell battery charger

Nanocrystalline solar cell kit

Triton soap

glass stirring rods

Hand-cranked electrical generators

multimeters for assessing voltage

Watering can, bucket, cup, and waterwheel for a water elevation demonstration as an analogy to electron diagram for DSSC.

IV. Supplementary materials, handouts.

Photosynthesis energy storage diagram (I will use the diagram from the BSCS text)

Biological energy flow diagram (p.65)

Greenhouse effect diagram (p.66)

Increasing CO₂ concentration diagram (p.67)

Energy diagram for a DSSC (p.69)

Five-E Organization

Teacher Does Probing Questions Student Does

Engage: Lesson Plan Day 1 Nanocrystalline Solar Cells. Engagement: Instructor brings out several different power sources. A silicon solar cell, hydrogen (H2) fuel cell, a dye sensitized solar cell, a rechargeable battery, an apple, a wooden matchstick, and fossil fuel (candle oil). Instructor turns on the power sources one at a time while taking answers from the students. The candle will be lit, the matchstick burned, the apple bitten, a cell phone turned on, a calculator switched on, and a hydrogen fuel cell car darts across the room at the end of the engagement. The answer is “The Sun”

Where does the energy in each one of these items come from? If they do not get to the answer before the instructor is halfway through, a hint can be given “All of them get their energy from the same source.”

Initially, they may say the energy in the fuel oil comes from a dinosaur, or that the energy in the wood comes from a tree Instructor asks where the tree or dinosaur got its energy until the ultimate answer is reached.

Explore: Students will be given hand-cranked generators and they will learn how to measure the voltage coming from them with a multimeter. They will also measure the voltage coming from the solar panels and the H2 fuel cell. Students will hook two hand-cranked generators together and will count the efficiency of conversion by the number of cranks one generator can make the other one (now a motor) can turn.

Which would make the fuel cell car run more efficiently, the solar panel without the fuel cell, the fuel cell alone, or the combination? Which one of the choices above is the most useful and the safest? 10 cranks of one hand-held generator will give how many turns of the motor? What is the efficiency %? Is the overhead projector lamp an efficient source of power for the solar cell? What would be more efficient?

The solar panel alone is most efficient. The fuel cell + solar panel- so the car still functions at night and on a cloudy day. efficiency is calculated as a ratio of the motor/generator cranks. No, it has been converted to many different forms on its journey, and this leads to loss of energy at each conversion. Direct sunlight would be most efficient.

Explain: The second law of thermodynamics

What are some forms the ”lost” energy takes when it is converted from one form to the next? How can energy be stored non-chemically?

Heat, friction, air resistance, magnetic field, light. (Hint: does your cellphone feel different after it has been charged or discharged in a long conversation?) (Hint: point to the water demo- is this storage of chemical energy when I lift the water?) As potential energy or kinetic energy

Extend / Elaborate: Ask students about the consequences of capturing and storing energy. Relate this to the heat problem on Earth

How can I turn plant photosynthesis into useful work? What would happen if all of the plants on Earth died- would it get hotter or cooler? What would happen if we coated the deserts of Earth with Solar panels?

food for a person human exercise to make electricity and improve health (H: hand generator). Burn plant to boil water, to turn turbine, to make electricity. Earth would get hotter without plants because light would become heat directly. Earth would be cooler and the desert would be cooler—until the energy is released to do work.