CO₂ Sources, Purity and Beneficial Reuse with CarbonCure

Welcome back to Concrete Corner! This the second blog post of the two part series on CO₂ supply written by Diane Praught, CarbonCure’s Director of Technical Services. Be sure to check out part one, too!

A very common question CarbonCure team members encounter is: “Why is it important to have high purity merchant CO₂? Can’t we just use any old CO₂?”

The short answer: We could technically use lower purity sources for CarbonCure, however, right now, the same CO₂ that goes into concrete, also goes into your food!

For some context: The merchant CO₂ market primarily supplies the food and beverage industry.

Any time you open a can of soda or pick up a bag of frozen peas at the grocery store, there’s a high likelihood that merchant, high purity, captured CO₂ has been used somewhere in its manufacturing process. “Food grade” merchant CO₂ can be used to carbonate the beverages we love or to quickly freeze food products for transport and storage.

Merchant CO₂ is also heavily regulated due to its use in the products we consume, and in order to maintain their certification as a source of food-grade CO₂, capture plants are required to submit regular test reports showing the purity of their end product.

While this level of purity and regulation is critical for the food and beverage industry, it is not necessarily required in concrete. However, since this high-purity CO₂ is the source that is readily available—it is what CarbonCure customers currently use.

“Why does this CO₂ come from ethanol plants and refineries instead of cement plants?”

Industrial gas supply companies are on the hunt for the “closest to pure” and highest production sources CO₂ they can get. In this context, “closest to pure source” means that the waste CO₂ emitted from the plant effluent is primarily made up of CO₂ molecules, as it lacks other trace elements (or has a very low concentration of them).

Effluent streams that contain a lot of impurities, or components that are not CO₂, are more difficult to process and purify. Therefore the purification process would require more energy, increasing the length and cost of the process, which is currently less desirable to companies in this competitive landscape.  

Unfortunately, effluent streams from cement plants is not considered a high purity-high concentration source of CO₂ when compared to many other available options. As a result, cement plants aren’t generally on the radar for the larger industrial gas suppliers as a capture option—because at the end of the day, they need to choose a supply option that makes business sense to support their largest industry—food processing.

Interestingly, the majority of industries that will use these waste sources of merchant CO₂ will not be putting the product to beneficial reuse. When a can of soda is opened, the CO₂ that was used to carbonate will escape—when the peas thaw, the CO₂ used to freeze them will be released back into the atmosphere. Although merchant CO₂ is a safe, cost effective and an important part of our food and beverage supply chain, it lacks a net positive environmental impact.

CarbonCure provides customers an opportunity to have a net positive environmental impact that these other industries lack. The waste CO₂ recovered from ethanol and fertilizer plants can now be permanently trapped in concrete as a mineral—making a lasting environmental impact that concrete producers can feel proud of.

A reduced carbon future for the cement and concrete industry?

There is a strong and growing demand from the construction industry to source CO₂ from cement plants. To address this need, CarbonCure and its partners have been working together on reliable, cost effective, and efficient CO₂ capture from cement plants—with the goal of closing the carbon loop to elevate the environmental image of the cement and concrete industry. With the growing global trend of beneficial re-use of waste CO₂, new uses for industrial grade CO₂ are entering the commercial market every day— opening up exciting business opportunities for CO₂ captured from cement plants.

Learn more about CarbonCure’s efforts in integrated cement plant CO₂ capture.

Until next time,

Diane Praught
Director of Technical Services
CarbonCure Technologies
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For more information on CO₂ for CarbonCure Technologies applications, or for requesting topics for future posts, please contact Diane at dpraught@carboncure.com.