Publish at October 03 2022 Updated December 16 2022

How does a 750 gram liter of gasoline emit 2.3 kilos of CO2?

The combustion of all fossil fuels is part of the same chemistry

You may have already been intrigued by the emissions figures of CO2 from traveling by car or plane. For example:

  • a 1,000 km trip by car emits about 270 Kg of CO2;
  • a one-way Paris / New York flight by plane represents about 1.25 to 1.5 tons of CO2 per passenger. 

Or, In both cases, there seems to be a conflict with our impressions: a full tank of a full tank of gasoline does not weigh 200 Kg and a plane with 300 passengers could not could not take off with 400 tons of fuel. Are we being taken for fools? Before your students start bothering you, here are the answers. They are found in the chemistry of combustion.

A matter of combination

Gasoline is made up of hydrocarbons, otherwise known as hydrogen (H) and carbon (C) atoms that form hydrocarbon molecular chains (CxHx), such as octane (C8 H18), heptane (C7 H16), benzene (C6 H6) and dozens of others. dozens of others.

To understand the calculation, one must know that

  • hydrogen is of atomic weight of 1,
  • carbon is of atomic weight of 12 and
  • oxygen of 16.

When fuel is burned, it combines with oxygen to form water molecules H2O and CO2 molecules while releasing a lot of energy. Other molecules such as carbon monoxide (CO) are also emitted, but in minimal proportions to the total.

Each carbon atom (12) bonds with two oxygen atoms (16), resulting in a CO2 molecule with a molecular weight of 44 (12+16+16). In other words, each kg of carbon burning in air produces 3.67 kg of CO2.  (44/12 = 3.67).

So a liter of gasoline, which weighs 750 grams and contains about 630 grams of carbon, produces 2.3 kg of CO2. (0.630 x 3.67)

To get an idea of volume now, one kg of CO2 occupies a volume of 510 liters at normal pressure and temperature. So our liter of gasoline emits more than 1100 liters of CO2!!!  Fortunately CO2 is invisible and odorless.

Some more

This liter of gasoline or kerosene is derived from crude oil. Extracting the oil, transporting it, refining it, distributing it emits CO2 at every step and many other gases such as methane, sulfur compounds and others.

  • Extraction at great depths, in remote areas or from the tar sands increase the carbon footprint.
  • Shipping, transshipment or leaks in pipelines, refining and especially flaring (burning volatile gases that are too difficult to liquefy and not very profitable) also emit their share of CO2.
  • Finally, the transportation and distribution of refined products throughout the network and often over great distances also consumes fossil fuels.

In short, the production and distribution of the liter of gasoline that one pours into one's tank has already emitted a fair amount of CO2 before it is even consumed.

Individual carbon offsetting must also be supplemented by industry offsetting, which starts to add up to an impressive total per final mile driven.  Surely we can do better and more efficiently. It's all about moving people and goods, not necessarily cars and trucks.  The liter of gasoline not consumed is worth far more than any carbon offset.

That's still not enough

Coal locomotives are gone as is coal-fired home heating, but coal use continues to grow globally, especially to meet the ever-increasing demand for electricity.

Highly energetic, coal is 50% to 97% carbon. One ton of coal emits almost 3.50 tons of CO2 and many other sulfurous gases. The estimated global coal reserves are 22,000 billion tons, enough to transform the atmosphere; multiply by 3.67!"

These reserves are spread all over the earth and many countries cannot, for the moment, do without its use. What government could propose to its population a radical reduction of its energy consumption and necessarily a limited economic future? We have a lot of changes to make, especially in our mentalities.

The atmosphere knows no borders, neither do our policies after all.

Illustration: DepositPhotos - ssuaphoto


CO2 Emissions Calculation- Climat Mundi -

Calculate your carbon footprint - flight - Ecotree -

Carbon Footprint -

Facts: Fuel Consumption and CO2 - Natural Resources Canada

How is CO2 calculated in kilograms?

Carbon - Wikipedia -

See more articles by this author




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