Introduction
As wind and solar power expand, storing energy for later use becomes critical. But not all storage systems are equally efficient. In this lab simulation, you’ll analyze how well different systems store and return energy.
Your Challenge
- Use the materials provided by your teacher to study and build background knowledge on three energy storage methods: Li-ion batteries, supercapacitors, and pumped hydro. Note their function, uses, and efficiency characteristics.
- Choose one energy storage method and design a hypothetical experiment to measure its efficiency.
- Analyze provided sample data, and reflect on what the results tell you about energy storage in the real-world.
Storage Methods at a Glance
| Method | Type | Use Example |
|---|---|---|
| Li-ion Battery | Chemical | Electric vehicles |
| Supercapacitor | Electrostatic | Short bursts of power |
| Pumped Hydro | Gravitational | Large-scale grid-backup |
Lab Simulation Procedure
You won’t be building or testing a real energy storage device, but you will design a plan for how a scientist or engineer could test how efficient one is. You’ll also use sample data to “run” your experiment and evaluate your design.
Use the prompts below to plan your experiment clearly and scientifically.
STEP 1: Choose a Method
Pick an energy storage method to investigate, and explain why you are choosing this method. You will be designing an experiment to measure its efficiency.
STEP 2: Write a Hypothesis
Make an educated guess about how efficient your chosen storage method will be and why. Efficiency is measured as a percentage (energy output divided by energy input). 90-100% efficiency is very high. The lower the percentage, the lower the efficiency.
Example: I think [energy storage method] will have [high or low efficiency, include percentage] because [explain reasoning].
STEP 3: Identify the Variables
In every good experiment, you control some things and measure others.
| Independent variable: Dependent variable: Controlled variables: |
STEP 4: Describe your Procedure
Tools That You’re “Imagining” in This Procedure
Since this is a thought experiment, you won’t be using real equipment. But here is what engineers would use in real life.
- A power supply (like a solar panel) that charges the energy storage system (adds energy in).
- A tester (like a multimeter) that measures how much energy is stored or released.
- A load (like a device with a small motor) that runs by using the stored energy.
Your procedure will describe how to use these tools to collect data for input and output energy.
What You Need to Remember
- You don’t need to build anything.
- Hypothetical trial data for input and output energy will be provided for you in the next step to calculate efficiency.
- The purpose of writing the procedure is to provide step-by-step instructions for how your experiment might work.
Input, Output, and Efficiency
Before you design your simulation experiment, you need to understand what it means to charge an energy storage system (input energy), use an energy storage system (output energy), and how to calculate efficiency using these values.
Key Point: Not all the energy you put in when charging is returned when using the energy storage system.
Key Terms
- Energy Input: The total amount of energy (in kilojoules, or kJ) used to fully charge a battery.
- Energy Output: The amount of energy (kJ) the battery gives back when it is used to power something.
- Efficiency: A percentage that shows how much of the input energy is actually used.
- Formula: Efficiency% = (Output Energy ÷ Input Energy) x 100
In the steps below, write instructions for how you would conduct your experiment. Try to answer the questions, “How would you input energy into the system? How would you measure how much energy came back out? How would you make sure your test was fair and consistent?”
Hypothetical trial data for input and output energy will be provided for you in the next section to analyze data and calculate efficiency.
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Note: If more steps are needed, use an additional sheet of paper.
STEP 3: Analyze the Data
Below are hypothetical data tables that you will use to calculate the efficiency of your chosen energy storage method.
Hypothetical Data Tables
| Storage Method | Trial | Energy Input (kJ) | Energy Output (kJ) |
|---|---|---|---|
| Li Battery | 1 | 500 | 450 |
| Li Battery | 2 | 500 | 430 |
| Li Battery | 3 | 500 | 460 |
| Storage Method | Trial | Energy Input (kJ) | Energy Output (kJ) |
|---|---|---|---|
| Supercapacitor | 1 | 1000 | 850 |
| Supercapacitor | 2 | 1000 | 870 |
| Supercapacitor | 3 | 1000 | 840 |
| Storage Method | Trial | Energy Input (kJ) | Energy Output (kJ) |
|---|---|---|---|
| Pumped Hydro | 1 | 2000 | 1600 |
| Pumped Hydro | 2 | 2000 | 1650 |
| Pumped Hydro | 3 | 2000 | 1580 |
STEP 4: Fill in Your Data Table
Take the hypothetical data of your chosen storage method, and use the efficiency formula to calculate efficiency, filling in the data table below.
Formula: Efficiency (%) = (Energy Output ÷ Energy Input) × 100
| Storage Method | Trial | Energy Input (kJ) | Energy Output (kJ) | Efficiency (%) |
|---|---|---|---|---|
STEP 5: Analyze, Reflect, and Conclude
- What is the average efficiency for the storage method you chose, using the data you calculated? Show your work.
- Did your results prove or disprove your hypothesis? Explain why.
- Based on the full data table, which storage method had the highest average efficiency? What might explain its performance?
- What are some real-world conditions that could affect how efficient an energy system is?
- Besides efficiency, what other factors should be considered when choosing an energy storage method?
- Based on what you learned, what kind of job or purpose is your chosen storage method best suited for? Explain why.
- Why is it important to understand energy storage efficiency as we harness more hydropower, wind, and solar power?
- What kind of energy storage technology do you think will be important in the future, and why?