Carbon dioxide: Trash or valuable chemical?

As the world moves towards its Sustainable Development Goals (SDGs), the call for a cleaner-greener-future is at an all-time high. One of the major steps in this regard is the sequestration of CO2. However things get interesting when we look at the scale required. What to do with this CO2? Should we consider it trash – something to waste? Or should we, by using technology and innovation, use this for the benefit of the economy and the environment? Important products like Sustainable Aviation Fuels (SAF) and many other industries in the various market segments depend upon the availability of CO2.

Before we discuss the utilisation of CO2 as a feedstock for SAF, it is imperative to mention some properties of this fuel and highlight the pivotal role it may play in creating a sustainable future. SAF is a biofuel that can be used in aeroplanes, essentially replacing conventional jet fuel (kerosene). The difference is that SAF has a very low carbon footprint, and in some cases, its impact on Green House Gas (GHG) footprint can be net-negative. As per the Environmental Protection Agency (EPA), the aviation industry contributes around 12% to the total transportation GHG emissions. On a global level, the industry is accountable for 4% of global warming. It is also one of the most challenging sectors to implement decarbonisation policies due to the fact that they are not fixed to one location. 

^{Source: Our World in Data}

Therefore, any low carbon fuel that can help us achieve decarbonizing transportation should be embraced and deemed important. CO2 is used as a main feedstock in creating SAF, and many companies are seeking to produce this important decarbonisation tool. Take, for instance, Air Company, which signed a $65 million project with the U.S. DoD, to capture the CO2 from military basis and used that to produce Sustainable Aviation Fuel. How is this achieved? First the CO2, through various processes, is converted into CO (carbon monoxide) which is then reacted with green Hydrogen (H2) creating liquid hydrocarbons which are subsequently converted into SAF. Another process, Alcohol to Jet (ATJ) involves the conversion of ethanol or butanol into jet fuel after passing them through a fermentation process which releases CO2. Instead of taking it out it is reintroduced into the system to expedite the fermentation process!

The company mentioned above utilizes CO2 from industrial sites and processes it through their own electrochemical reactor where CO2 is converted into CO and through a separate process of electrolyzed water is split into Hydrogen and Oxygen. This is passed through what is called Fischer-Tropsch process converting the syngas to liquid fuel.

Furthermore, there are other industries that also benefit from CO2.

The Beverage Industry has been one of the top industries which composes the largest consumer of CO2 for the production of carbonated beverages such as beer, soda and sparking water.  CO2 is significant as it increases the shelf life of the beverage and adds fizziness, enhancing its taste and form. PepsiCo is an example of a large buyer of CO2 gas from large industrial gas majors such as the Messer group.  To meet the demands of its clients around the world, the Messer group is constantly in the process of opening new production sites and exploring new ways to fulfill this demand. It is worth noticing that around 70 percent of CO2 produced in US is used in the beverage and food industry. On the other hand, due to increasing energy costs, the beverage industry is facing a global shortage of CO2 and is looking for its substitute like Nitrogen. According to the Energy & Climate Intelligence Unit, the cost of CO2 has increased to 3,000 percent since 2021. 

CO2 is significantly used as a raw material in the chemical processing, like of urea, melamine and methanol. Approx. 2 million tons of CO2 is used per year for the production of methanol. According to IEA, in 2021, the chemical industry's global emissions of CO2 reached approximately 925 million metric tons. 

It is estimated that the Carbon Dioxide Market may reach USD 17.13 billion by 2031 as it has been widely used by the Food, Drink and Medical industries. CO2 has been widely used in the medical and healthcare industry as it aids the surgical processes like endoscopy and laparoscopy. It is also used as a stimulus to regulate the respiratory system after the anesthesia intake. 

What if we choose not to send the captured CO2 into the markets?

The most important question, therefore, is what will happen if the CO2 (which is being captured) is not sent into the markets as described above. Also, what may be the main motivation behind it? First of all, there can be production halts and supply chain issues, for example, the beverage industry stops getting the CO2 feedstock. While fertilizer plants emit CO2, this gas is captured and used in controlled atmosphere storage to preserve vegetables, fruits, and grains, extending their shelf life and reducing spoilage. Any disruption to this process can result into food wastage and (in the longer run) an increase in food prices. Moreover, another pressing and associated issue with stopping the circularity of carbon dioxide is how long can we store it and will there be any potential impacts of it? The sequestered CO2, if stored underground, comes with its own potential risks. First of all, scientists have yet to find ways to stabilize the gas as it may takes up-to 1000 years for that to happen. It can also induce seismic activities as the CO2 can impact the subsurface rock formations and pressure. There is also a risk of leakages which can contaminate groundwater and/or the soil nearby. C02 is also highly unpredictable and so far we do not possess the technology to predict the long term impact of the storage wells on the surrounding geology.

Consequently, the next time you debate CO2 sequestration, make sure to end the debate around its final utilization. Understanding things holistically is crucial when it comes to energy transitions and the move towards a greener future.