CO2 Applications

Carbon dioxide (CO2) is known globally as a greenhouse gas (GHG) that contributes to climate change.  However, CO2 is a very useful and versatile molecule with many different applications across a wide variety of industries.

  

The use of CO2 as an input is a promising alternative for GHG mitigation.  Because it is an abundant material, of low commercial value and non-toxic, CO2 continues to have great potential for use as a raw material for the chemical industry.  CO2 is currently used to add carbonation to beverages (soft drinks, water, and beers), to extinguish fires, in welding processes, and to keep food items cold during transportation in the form of dry ice.

  

New pathways involve transforming CO2 into fuels, chemicals, and building materials.  The production of CO2-based fuels & chemicals is energy-intensive and requires large amounts of hydrogen.  Figure 1 shows a simple classification of pathways for CO2 use.

  

CO2 as raw material

 

Materials capable of cost-effective CO2 conversion into chemicals & fuels help stabilize atmospheric GHG levels.  Potential products obtained w/ CO2 conversion are formic acid (HCOOH), methanol (CH2OH), carbon monoxide (CO), and ethylene (C2H4).

  

The reduced industrial use of CO2 is due to its high thermodynamic stability & low chemical reactivity: as consequence, industrial processes aimed at the chemical transformation of CO2 must require high amounts of energy and the use of catalysts, which increases the processing cost, discouraging such application.

  

Furthermore, CO2 conversion reactions either give rise to products with a lower oxidation state of carbon, such as hydrocarbons & methanol, or products in which the oxidation state is maintained, such as carbonates.

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CO2 purity

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Depending on the input CO2 stream and intended use, a series of purification steps may be required before transport & utilisation, which can add to the overall cost of supply of CO2: purity requirements on CO2 for beverage carbonation (CO2 purity at 99%) can increase costs; mineral carbonation, in turn, requires low purity CO2.  CO2 purification approaches include cooling, compression, drying, and adsorption to remove impurities, such as H2S gas or water [CSIRO, 2023].

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First CO2 market from CC

  

In the early 1970s Chevron leftover CO2 captured (CC) from an oil field to produce more fuel at scale (it was used to squeeze out extra oil, a technique known as Enhanced Oil Recovery (EOR).  For the next 30 years this was the main application of carbon capture: not constraining GHG emissions but producing even more fossil fuels [BNEF, 2023].  Figure 2 shows the CO2 market share in 2015.

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CO2 traditional & emerging markets

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Globally, 230 MtCO2 are used every year.  The largest consumer of CO2 is the fertilizer industry, where around 130 MtCO2 per year is used in urea manufacturing, followed by the oil sector, with a consumption of 70-80 MtCO2 for enhanced oil recovery (EOR) [IEA, 2019].

  

Barriers to near-term scale up of CO2 use are commercial & regulatory rather than technological.  This analysis considers the near-term potential for increasing the market to at least 10 MtCO2 use per year for each of the five categories of CO2-derived products & services: fuels, chemicals, building materials from minerals, building materials from waste, and CO2 use to promote plant growth: this level of CO2 use would be almost as much as the current CO2 demand for F&B (food & beverage) industry.

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Key takeaways [IEA, 2019]

  

• New pathways to use CO2 in the production of fuels, chemicals, and building materials are generating global interest.

• The market for CO2 use will likely remain relatively small in the short term, but early opportunities can be cultivated.

• CO2 could be an important raw material for products that will continue to require carbon due to their structural properties (e.g., carbon-containing chemicals) or because the use of carbon-free energy carriers is challenging​ (e.g., aviation fuels) [IEA, 2023].