What it shows
Burning fuel makes carbon dioxide, a greenhouse gas. By linking distance, mileage and fuel type you can estimate how much CO2 each way of getting to school sends into the air.
The science
Burning one litre of petrol releases about 2.3 kg of CO2 and one litre of diesel about 2.7 kg, because carbon in the fuel combines with oxygen. The CO2 for a trip is the fuel used times these numbers, and the fuel used is the distance divided by the mileage in km per litre. A bus shares its fuel among many passengers, so its CO2 per person is smaller, while walking and cycling give none from fuel. The exact values change with traffic and how full a vehicle is, so the answers are estimates.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A survey sheet for classmates with mode of travel, distance and vehicle type
- A map or a phone to measure the home to school distance
- Fuel mileage values from the vehicle owner or a mileage sticker
- A calculator or a spreadsheet
- Chart paper for a bar chart
- A list of CO2 per litre of fuel
- A notebook
Safety
For this project: Do not ask for names or addresses, and only use data that students share willingly. Use code numbers instead of names.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Design a short survey: mode of travel, one-way distance, vehicle type and the number of people in it.
Collect data from at least 40 students. Use code numbers, not names. Convert distances to kilometres.
For each car or two-wheeler, find the mileage and calculate fuel used for the round trip as 2 x distance / mileage.
Multiply by 2.3 for petrol or 2.7 for diesel to get kg of CO2 for the day. For a shared vehicle divide by the number of people in it.
For buses use a typical emission of about 0.03 to 0.05 kg per passenger-km from a published source, writing the source, or ask the transport office for fuel use and passenger numbers.
Total the CO2 for each mode for the whole class for one school day and for 200 school days.
Draw bar charts of CO2 per student and CO2 per kilometre for each mode.
Propose a plan, such as car pooling or a cycle day, and calculate the CO2 saved if 10 per cent of students changed their mode.
What you should see
A table and chart showing that car trips by one person cause the most CO2 per student, buses and shared vehicles much less, and cycling and walking none from fuel, with the total saved by your plan.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Why does burning fuel make CO2?
The carbon in the fuel combines with oxygen from the air when it burns.
2How much CO2 does one litre of petrol make?
About 2.3 kg.
3Why is a bus better per person?
Its fuel is shared by many passengers.
4Are walking and cycling completely free of carbon?
They avoid fuel use, though making bicycles and food gives small emissions.
Take it further
Estimate how many trees would be needed to absorb the class’s yearly travel CO2, taking about 20 kg of CO2 absorbed per tree per year for a mature tree.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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Your Science Exhibition Guide
Choose a project, build it, present it and answer the judges with confidence
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