Introduction

The Olympic flame is one of the most recognizable symbols of the Olympic Games, representing unity, peace, and continuity across generations. Traditionally, the flame has been a real, continuously burning fire, carefully engineered to remain lit throughout the Games under all weather conditions. In recent Olympics, organizers have explored alternative designs intended to reduce CO₂ emissions, including electric flame effects and combustion systems using alternative fuels. These changes have sparked public debate about how technological innovation should interact with cultural tradition.

In this activity, students investigate the energy use and environmental impacts of different Olympic flame designs. Using realistic assumptions and engineering-style estimates, students calculate energy consumption and CO₂ emissions for a traditional combustion flame, an electric flame powered by different electricity sources, a hydrogen-powered flame, and a biofuel-based flame. Students then evaluate trade-offs between symbolism, energy systems, and environmental impact through a Claim-Evidence-Reasoning (CER) task. 

Student Objectives

Students will be able to

• Calculate energy consumption using power and time relationships.
• Estimate and compare CO₂ emissions from different energy systems.
• Explain how energy use can remain constant while emissions change, depending on the energy source.
• Describe how electrification shifts emissions upstream from the point of use to energy production.
• Evaluate why no energy system is impact-free, and how environmental, technical, and cultural trade-offs influence design decisions. 
• Interpret how different electricity generation methods influence total emissions.
• Construct a Claim-Evidence-Reasoning (CER) argument using quantitative and qualitative evidence.

Materials

• Student Handout

Procedure:

Step 1: Engage: Introduce the Olympic Flame

• Begin by discussing the symbolism and history of the Olympic flame. (Optional Resource: The Olympic Flame and the Torch Relay describes the significance and cultural importance of both the torch relay and the lighting of the Olympic flame in the stadium). Emphasize that it is not only a technical object, but also a cultural symbol that carries meaning for athletes and spectators around the world. 
• Provide each student with the Student Handout (or have students work in pairs). Bring their attention to recent Olympic flame innovations, including Paris 2024’s electric flame (Part 2), and Tokyo’s 2020 hydrogen-powered flame (Part 4), and note that these changes have generated mixed public reactions.
• Facilitate a short discussion using questions such as:
  • Why do people care whether the flame is “real”? 
  • What expectations might the public have for the Olympic flame? 

Step 2: Explore: Traditional Flame Energy and Emissions

• Have students work through the first section of the Student Handout to estimate the energy use and CO₂ emissions of a traditional, propane/butane combustion Olympic flame. Encourage students to show their work and discuss assumptions, such as constant power output and continuous operations.
• Check understanding of the difference between Power and Energy, Watts (W) and Kilowatt-hour (kWh) units, and where emissions originate in combustion systems. (Note: Additional practice with these units can be found in the Energy Units Math Challenge activity.)
• Note: The CO₂ values in the Student Handout are simplified estimates used for comparison, not exact lifecycle values.

Step 3: Apply: Electric Flame and Energy Source Comparison

• Guide students through the electric flame calculations (Parts 2 and 3 of the Student Handout), first assuming electricity generated primarily by nuclear power (France 2024) and then by coal in a hypothetical scenario. Emphasize that the energy required for the flame does not change; only the energy source does.
• Use discussion prompts to highlight why emissions vary by electricity source, and why electrification alone does not guarantee lower emissions.
  • Why does the electric cauldron use the same amount of energy no matter how electricity is generated? 
  • Why do emissions change even when energy use stays constant? 
  • Does using electricity automatically mean low CO₂ emissions?
  • What information would you want before deciding whether an electric system is truly low-carbon?

Step 4: Extend: Hydrogen and Biofuel-LPG Flame Analysis

• Students calculate energy use and emissions for Tokyo’s 2020 hydrogen combustion flame, and a hypothetical Biofuel-LPG cauldron for Milano-Cortino 2026.
• Reinforce that biofuels involve trade-offs. They still emit CO₂, but may differ in carbon origin and lifecycle impacts.
• The hydrogen used in Tokyo was produced by electrolysis using solar power. Hydrogen produces no CO₂ at the flame, but producing hydrogen via electrolysis requires electricity. The electricity source will have a significant impact on estimated CO₂ emissions from hydrogen production by electrolysis.
• Encourage students to compare all systems and consider immediate emissions versus long-term carbon cycles, and the practical constraints of the Olympic flame design. 

Step 5: Evaluate: CER Design Decision

• Students complete the CER task, selecting a flame design they believe best balances symbolism, tradition, and environmental impact.
• CER (Claim-Evidence-Reasoning) is a structured framework for scientific argumentation.
  • Claim: A clear, direct answer to the question being asked. 
  • Evidence: Data or observations that support the claim. In this activity, evidence may include calculated energy use (kWh), calculated CO₂ emissions (kg), historical or cultural considerations, and/or statements from Olympic organizers. 
  • Reasoning: An explanation of why the evidence supports the claim. Reasoning should connect evidence back to scientific principles, acknowledge trade-offs and limitations, and address counterarguments when appropriate.
• Reinforce that strong CER responses do not require a “correct” answer. They require clear logic, accurate evidence, and thoughtful justification.

Answer Key

Part 1: Traditional Combustion Flame

1. Daily Energy Use: 300 kW x 24 hr = 7,200 kWh per day
2. Total Energy: 7,200 kWh x 16 days = 115,200 kWh
3. Total CO₂ emissions: 115,200 kWh x 0.20 = 23,040 kg CO₂
4. Fuel burned per hour: 300 kW / 13.9  = 21.6 kg per hr
5. The CO₂ comes from carbon atoms in the fuel. When hydrocarbons burn, carbon combines with oxygen to form CO₂ (combustion reaction). 

Part 2: Paris 2024 “Electric Flame Effect”

1. Daily Energy Use: 40 spotlights x 100 W = 4,000 W
   4,000 W x 24 hrs = 96,000 Wh per day
   96,000 Wh / 1,000 = 96 kWh per day
2. Total Energy: 96 kWh x 16 days = 1,536 kWh
3. Total CO₂ emissions: 1,536 kWh x 0.02 = 30.72 kg CO₂
4. Power plants and infrastructure have lifecycle emissions (mining materials, construction, maintenance). Some electricity grids include mixed sources. Fuel processing, transport, and backup systems can add emissions.

Part 3: What If Electricity Came From Coal? 

1. Total CO₂ emissions: 1,536 kWh x 0.90 = 1,382.4 kg CO₂
2. No. It depends on how the electricity is generated, if the energy source is low-carbon or high-carbon. Coal-heavy electricity can cause high emissions.
3. Because emissions can happen upstream at the power plant. The “electric flame” shifts emissions from the stadium to the electricity generation system.

Part 4: Tokyo 2020 Hydrogen-powered Flame

1. Daily Energy Use: 900 kW x 24 hrs = 21,600 kWh per day
2. Total Energy: 21,600 kWh x 16 days = 345,600 kWh
3. Fuel burned per hour: 900 kW / 33.3 = 27.0 kg per hr
4. Making hydrogen with high-carbon source electricity; manufacturing equipment; transport and storage systems.
5. To showcase innovation and national energy strategy; demonstrating leadership in future fuel technology. 

Part 5: Milano-Cortina 2026 Hypothetical Biofuel-LPG Cauldron

1. Total CO₂ emissions: 115,200 kWh x 0.10 = 11,520 kg CO₂
2. Biofuels come from recent biological carbon (plants/organic waste), not ancient fossil carbon. They can be made from waste sources such as cooking oil and animal fats. 

Part 6: Claim-Evidence-Reasoning (CER) Design Decision: Student answers will vary.
Part 7: Final Reflection: Student answers will vary.