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3 Overview of carbon dioxide
Carbon dioxide is a molecule consisting of an covalent bound between two oxygen and one carbon atom. At standard conditions carbon dioxide is a gas and part of the earth’s atmosphere. Carbon dioxide in the atmosphere is absorbed by plants, algae and bacteria to generate energy with oxygen as a byproduct. Carbon dioxide is introduced into the atmosphere by natural causes like respiration of organisms, fires and volcanoes, but also by combustion of fossil fuels which is mainly human-caused.
Carbon dioxide is becoming a well known compound to the general public due to the current discussions on global warming, greenhouse gases and carbon capture and storage applications. Before this, carbon dioxide was already encountered in many ways or used in different applications. CO2 is a well known waste product of our own respiration, but is also produced during baking processes (making bread dough to rise). This fermentation process also occurs in the production of beer or sparkling wines. The artificial application of “CO2 bubbles” is found in many soft drinks and soda water.
The properties of CO2 allow it to be stored in liquid phase at high pressure occupying less space compared to the normal gaseous form at atmospheric pressure. This behavior has led to many applications of CO2 in propellant or pneumatic devices, like pneumatic guns or for inflation of tires, life vests or airbags.
Carbon dioxide is also used in fire extinguishers, for welding or as a solvent in liquid form. For the enhancement of plant growth the air in greenhouses can be enriched by adding CO2. This is already applied at large scale in the Netherlands.
Another large scale application of carbon dioxide is to use it for tertiary enhanced oil recovery, which is successfully performed in the USA for over 40 years. CO2 is injected in oil reservoirs both for pressurizing the reservoir and to mix with the oil to reduce its viscosity and as such enhances its recovery rate. It can also be injected in coal beds for recovery of methane.
The physical properties of carbon dioxide make it highly suitable to be applied as a refrigerant. Also in solid phase, better known as “dry ice”, it is often applied as a refrigerant.