Understanding Carbon Footprints
A "Carbon Footprint" is the total amount of greenhouse gases, primarily CO₂, produced by our actions. Whether it is heating a home, driving a car, or manufacturing a smartphone, almost every economic activity has an associated Carbon Emission profile.
The Combustion Chemistry
Most emissions come from burning fossil fuels. Fossil fuels contain carbon that has been locked away for millions of years. When burned, this carbon reacts with oxygen ($O_2$) in the air to form $CO_2$. Because oxygen is relatively heavy, the weight of the resulting gas is much higher than the weight of the fuel itself. For instance, burning 1 kg of carbon results in 3.67 kg of $CO_2$ gas released into the atmosphere.
Scope 1, 2, and 3 Emissions
Sustainability professionals categorize emissions into three "Scopes":
- Scope 1: Direct emissions from sources owned or controlled by a company (e.g., company vehicles, onsite boilers).
- Scope 2: Indirect emissions from the generation of purchased energy (e.g., the electricity you buy from the grid).
- Scope 3: All other indirect emissions in the value chain (e.g., employee commuting, waste disposal, supplier footprints).
Emission Factors Reference
| Source | Avg. emission (kg CO₂) | Standard Unit |
|---|---|---|
| Diesel | 2.68 | per Liter |
| Gasoline | 2.31 | per Liter |
| Grid Electricity | ~0.41 | per kWh |
Related Sustainability Tools
Frequently Asked Questions
How are carbon emissions calculated for fuel?
Emissions are calculated by multiplying the quantity of fuel consumed by its specific emission factor. For example, 1 liter of diesel produces approximately 2.68kg of CO2.
What is CO2e?
CO2e stands for CO2 equivalent. It is a metric used to compare the emissions from various greenhouse gases (like methane or nitrous oxide) based on their global-warming potential.
Why does burning 1kg of fuel create more than 1kg of CO2?
During combustion, the carbon atoms in the fuel combine with oxygen atoms from the air. Since oxygen has mass, the resulting CO2 molecule weighs significantly more than the original carbon atom.