The reduction of CO2 emissions currently is one of the most important topics not only in aviation but in industry in general. At the moment CO2 is mostly seen as a dangerous greenhouse gas causing our climate to change. Unfortunately, for carbon based life forms such as humans, CO2 will be the end product of nearly all our endeavours and the emission of CO2 cannot be avoided. So, could there be a way to make use of CO2?
CO2 is a molecule with a very low level of energy and therefore quite inert in its state. Still, living plants have found a way to transform CO2 into complex carbohydrates using solar power and even releasing oxygen into the atmosphere in the process. This process is obviously called photosynthesis and might point us in the right direction. Even though (at the moment) we cannot directly replicate photosynthesis by technological means, other ways might be found to process a molecule that contains an element like carbon which can be put to a multitude of uses. Recently photo catalysts have been developed that can be helpful in lifting CO2 molecules from their low energy state.
There exist processes now that can convert CO2 and water into CO and hydrogen which then can be processed to methanol. Another technology has polymers created by catalysis of CO2 and propylene oxide. All of these new technologies are based on advanced catalysts that help starting the chemical reactions and the development of new such catalysts is of paramount importance, as high value derived materials are required to justify financial and technological effort.
CO2 is available in large quantities, but is rarely found in places where it can be easily processed. Large amounts of unused and unusable CO2 have accumulated in the atmosphere, plus new CO2 generated by the industry, of which a minuscule part is used for Aspirin, soda water, decaffeinated coffee etc. This pure CO2 that is generated by many industrial processes should be harvested and processed before it can even reach the atmosphere.
Concerning the aeronautics sector, this leads to the question of whether there might be a way both to avoid the production of CO2 in aircraft engines (such as, for example, using electrical engines) and to reduce the amount of CO2 released into the upper atmosphere by directly processing the exhaust gases before they leave the aircraft.