CO2 Learning Centre

Definition of CO2

According to the Oxford Advanced Learner's Dictionary, carbon dioxide is a...

"Colourless odourless gas formed by the burning of carbon,
or breathed out by animals from the lungs"

CO2 is a non-poisonous gas that prickles your nose. It is the ingredient that puts the "fizz" in fizzy drinks.

The natural carbon cycle

The natural carbon cycle is what takes place when the carbon existing since the birth of the earth is travelling between the oceans, the atmosphere, living organisms etc. - as has always been the case.

Atmospheric CO2 can be naturally absorbed by plants through photosynthesis and transformed into organic material to be accumulated in the soil or to decompose or burn. For the latter two the organically stored carbon can be led back naturally to the atmosphere as CO2.

While all ecosystems rely on the natural carbon cycle – what has become of major concern is the anthropogenic (i.e. derived from human activities) contribution added by the combustion of fossil fuels. Fossil fuels derive from organic material being stored underground for several millions of years. Through combustion of fossil fuels, the carbon bound in the fuel underground is released as CO2, hence adding additional carbon to the carbon cycle – one result of this is an increase of the CO2 level in the atmosphere.

Your body and CO2

Recognize the feeling of getting tired and nodding your head, trying to keep awake during a meeting? In a closed room with a number of persons, the CO2 content in the air will over time be slightly raised and the oxygen level consequently reduced, causing one to get a bit sleepy...

This can be explained by the following:

The amount of CO2 in the air inhaled is 0.04%. In the exhaled air the CO2 totals 4.0% - amounting to approximately 40g CO2/hour per person when relaxed.

People react differently to CO2 but at 0.1% CO2 in the atmospheric air it is uncomfortable to some people. 0.2% will cause lethargy (and to some even nausea). However it is not until a concentration of 20-30 times higher that the CO2 level will become dangerous.

Examples of CO2 applications

The refrigerant CO2 
CO2 has been rediscovered as a so-called natural refrigerant (as opposed to the freon types).

The greenhouse gas CO2 
Contrary to e.g. nitrogen (N2) and oxygen (O2) - CO2 can absorb and emit heat during radiation, just like methane, water vapour, freon and nitrous oxide (laughing gas). If there were no greenhouse gases in the atmosphere, the mean temperature of the earth would be 33°C (91.4°F) lower.

The EOR agent CO2 
EOR stands for "Enhanced Oil Recovery". CO2 can dilute oil and raise the pressure in oil fields - enabling the recovery of more oil from the otherwise depleted oil fields.