In this era of global warming, the issue of carbon dioxide (CO2) has never been so current. Aside from its presence in the atmosphere in minuscule quantities (0.04%, compared to 78% for nitrogen, 21% for oxygen and 0.9% for argon), carbon dioxide is also produced by man from numerous industrial activities, in alarming proportions. To ensure its survival, the Earth has to come up with more ingenious ideas to not only limit greenhouse gases (GHG) emissions but also to sequester and transform carbon dioxide.
Capture and sequestration
The capture and sequestration of carbon dioxide consists of isolating the CO2, compressing it and sequestering it in various locations such as saline aquifers (deeper than the freshwater groundwater, they have the advantage of being spread over the whole planet, thus limiting transport), old coal veins and depleted oil fields. Sequestration of carbon dioxide can also be produced by mineralization. Icelandic researchers have been able to develop a process that allows them to exponentially accelerate this natural process (two years compared to dozens of decades), which consists of dissolving the CO2 in water, then injecting the mixture into rock. Imprisoned, the carbon dioxide finds it difficult to go back to the surface.
Transformation into a chemical compound
Although it is difficult to transform the CO2 molecule, many scientists are exploring this avenue to reduce the presence of carbon dioxide in the atmosphere.
Methane: Transformation of CO2 into methane (CH4) – the main component of natural gas – is being studied by French researchers at the Centre national de la recherche scientifique. This technique has several advantages, in particular in terms of costs: the process uses as a catalyst a naturally abundant and low-cost metal, iron, with light providing the source of energy that allows chemical transformation of CO2 into formic acid (CH2O2) then to methanol (CH3OH) and finally into methane. This transformation, similar to photosynthesis, lets the carbon be incorporated into a sustainable cycle, and not to eliminate it.
Oxalic acid: Desiring to convert the CO2 into a “useful material, Professor Kawatra of the University of Michigan has designed a purifier that transforms carbon dioxide into oxalic acid, which is a fundamental component for processing rare earths, part of the composition of cell phones. The results of this discovery are more than conclusive: Professor Kawatra’s purifier reduced by 50% the combustion emitted by the steam power plant at his university. Furthermore, the process uses soda ash, whose price ($200 per ton) is one hundred times less than that of specific amines ($20,000 per ton) that have been used up to now.
An effective fight against climate change consists not only of behaviour modifications (individuals, companies, governments), but also by the development of new processes – transformation, capture and sequestration of carbon dioxide – which could also prove to be more competitive.