The Lowdown on CarbonCure’s CO₂ Supply

Interested in learning more about how CO2 factors into concrete production, sustainable engineering and green building design?

Read the following blog post by CarbonCure’s Director of Technical Sales, Diane Praught, who answers some key frequently asked questions in this two-part series on CO2 supply.

One of the most common questions CarbonCure team members encounter when discussing the technology is: How can CarbonCure be environmentally friendly if you have to manufacture new Carbon Dioxide (CO2) to use it?

The short answer to this question: Merchant CO2 is not manufactured, it is a captured waste product.

CarbonCure is a technology that injects waste CO2 into concrete in order to improve the product’s compressive strength. Strength increases are achieved by means of a chemical reaction that takes place between the calcium oxide in the product’s cement and the CO2 that is introduced by the CarbonCure system. The reaction creates nano-calcium carbonate (CaCO3) minerals that improve cement efficiency and the performance of the concrete.

CarbonCure licenses its technology to concrete producers who benefit from the strength improvement. In turn, concrete producers market their concrete to end users, such as developers, who benefit from an end product with a reduced carbon footprint.

Another common question asked, especially by concrete producers, architects and engineers, is: “Where does the CO2 come from?

The missing piece of the puzzle at this point is the CO2 product itself. CarbonCure does not capture or distribute CO2, neither do ready mix concrete producers. As a result, CarbonCure producer-partners acquire their CO2 from local industrial gas supply companies.

Industrial gas supply companies are spread out across the globe and provide thousands of industrial and specialized gas products and technology applications to hundreds of industries. They have large scale CO2 capture facilities (often referred to as “CO2 Recovery Plants”) in strategic locations all over the world. In these recovery plants, they use the flue gas stream of partner refineries, ethanol plants, ammonia plants etc. to access, capture, purify and then distribute CO2 to their customers.

A diagram explaining the CO2 purification process.  (Source:  MOS Techno Engineers )
A diagram explaining the CO2 purification process.(Source: MOS Techno Engineers)

In these scenarios, CO2 is captured from the waste flue gas streams of these large emitter facilities, it is usually drawn into a CO2 processing facility, repeatedly condensed, compressed and dried, until a pure CO2 product is achieved. As a result, many of these facilities are able to produce a product that is 99%+ purity.

Industrial gas suppliers will move this purified CO2 by truck, rail or direct pipeline across a specified geographical region to distribution centers. Once CO2 is delivered to a distribution center, it is loaded into smaller trucks that specialize in transporting CO2 to its final destination—holding tanks that sit on their customers’ sites, commonly referred to as “Bulk” or “Microbulk” tanks.

CO2, a waste by-product of several manufacturing processes, is analogous to slag, which is a waste by-product of a single manufacturing process. What these two waste by-products have in common is that both can be harvested, processed and put to beneficial reuse in concrete.

A CarbonCure system hooked up to a microbulk tank storing CO2.
A CarbonCure system hooked up to a microbulk tank storing CO2.

It is important to note that in certain geographical areas, natural well sources of CO2 are available wherein CO2 is produced by geological processes underground (similar to oil and gas). Merchant CO2 can also be captured and purified from these sources in a very similar manner as effluent sources of CO2; however, these natural geological sources of CO2 account for a much smaller portion of global merchant CO2, and are also a form of capture, not manufacturing.

What differentiates CarbonCure Technology is the fact that the CO2 is not just sequestered or stored in the concrete; it is permanently embedded. Due to the chemical reaction that occurs once injected into a concrete mix, turning it into a mineral, the CO2 never re-enters the atmosphere even when the concrete is demolished.

Be sure to also read about the benefits CarbonCure brings to ready mix concrete producers and concrete masonry, as well as to those who specify the use of CarbonCure concrete in their building projects.Keep an eye out for part two of this series, where Diane will be discussing:

  • The purity of captured CO2, and why that matters
  • How CO2 suppliers choose their CO2 source
  • CarbonCure’s beneficial reuse of CO2.

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