CarbonCure’s Approach to Carbon Removal

Carbon dioxide removal (“carbon removal”) has become an increasingly important part of plans to hit global climate goals as outlined in the Paris Agreement. 

While definitions are evolving, most agree that there are two key criteria for a project or carbon credit to count as carbon removal: The CO₂ must be atmospheric and it must be permanently stored. CarbonCure’s technologies, which permanently store captured CO₂ in concrete via mineralization, provide a pathway to scale carbon removal opportunities in a hard-to-abate sector.

While CO₂ from any source can be mineralized through our technologies, we regard the following three sources of CO₂ as constituting carbon removal:

• Direct air capture (DAC) CO₂
• Biogenic CO₂ from waste biomass (commonly referred to as BiCRS or BECCS)
• Biogenic CO₂ from the industrial market (primarily from ethanol production)

In this post, we’ll dive deeper into the intersection of carbon removal and our technologies while addressing: 

• What does CarbonCure consider carbon removal?
• What CO₂ sources are available in the market?
• How does CarbonCure prioritize CO₂ sources?

What does CarbonCure consider carbon removal?

At CarbonCure, we use the term carbon removal in relation to our technologies when atmospheric CO₂ is injected and permanently stored in concrete via mineralization.

At a high level, carbon removal pulls CO₂ out of the fast carbon cycle (the movement of carbon between the atmosphere and the biosphere) and stores it in the slow carbon cycle (geologic formations or rocks). The exchange of CO₂ between the fast and slow carbon cycle occurs naturally over centuries or millennia, and technological carbon removal simply accelerates that process, allowing us to draw down and store atmospheric carbon in days or weeks.

CO₂ can be pulled out of the fast carbon cycle in a few different ways. It can be harnessed from biogenic sources via photosynthesis, either from biomass like plants and algae, or from industrial processes that use biomass as a feedstock, such as ethanol production. It can be absorbed directly from ambient air, as with direct air capture. And it can even be harnessed from different types of waste, such as with municipal solid waste and animal manure. 

The graphic below goes into more detail on how these atmospheric CO₂ sources stack up against other CO₂ sources currently available on the market.

Which CO₂ sources constitute carbon removal when paired with CarbonCure’s technologies.

To date, CarbonCure has permanently stored more than 1,000 metric tons of atmospheric CO₂ via mineralization in concrete, largely from ethanol sources. This means that, together with our concrete producer-partners, CarbonCure has delivered more than 1,000 metric tons of carbon removal! When considering additional sources of CO₂, such as ammonia and hydrogen, CarbonCure has mineralized more than five thousand metric tons of CO₂ in concrete, where it’s been locked away permanently, never to be re-released into the atmosphere.

What CO₂ sources are available in the market?

While CarbonCure seeks out atmospheric CO₂ whenever possible, the simple fact is that it is not always available, especially at the scale and distribution required to supply CarbonCure’s network of 700+ carbon mineralization systems worldwide. Further, this is especially true for pathways like DAC and CO₂ from waste sources, which remain in very early stages of development. While we expect supply from these sources to increase in the coming years, for now, they remain very low.

The chart below provides an overview of different CO₂ sources that concrete plants could reasonably expect to obtain for use with our technologies and the available supply of each.

Source: Analysis using data from Global CCS Institute CCS Facilities Database https://co2re.co/. EPA.

As is evident, there are clear supply constraints around different CO₂ sources, with DAC being the most constrained (supply is virtually zero). Industrial point-source capture, while much more abundant, is still supply constrained when compared to natural sources of CO₂, also called geologic wells or natural CO₂-bearing formations.

How does CarbonCure prioritize CO₂ sources?

When determining the optimal CO₂ source to use for our technologies, there are three key questions to consider:

• Is it available?
• What is the source?
• What is the cost?

First, availability. When CO₂ is injected into concrete with our technologies, the resulting mineralization maintains the concrete’s compressive strength. This reaction allows concrete producers to reduce the amount of cement used to make the same, high-performing concrete. As cement is highly carbon-intensive, any cement reduction is a carbon emissions reduction. 

For every 1 metric ton of CO₂ injected into ready mix concrete, 15 metric tons of carbon emissions are reduced through the resulting cement cuts.

Given the strong multiplier effect that CO₂ mineralization has on CO₂ reductions, the best CO₂ is the one that’s available. This is especially true given the projected growth of the built environment in the coming years at a rate of a new New York City every month for the next forty years, with concrete being the most used building material in the world. 

Time is clearly of the essence. It’s vital that our concrete producer partners have a consistent supply of CO₂ as soon as possible so that when they use CarbonCure’s technologies and inject CO₂, they are reducing emissions with every batch of concrete that they pour. Without CO₂, there’s no climate impact at all.

In addition to the question of timing, CarbonCure’s technologies are licensed in more than 700 concrete plants in more than 30 countries, and each plant can utilize up to 20 metric tons of CO₂ annually. This presents both a large opportunity and a large logistical challenge. At present, the industrial CO₂ market is the only supplier that can distribute the tens of thousands of metric tons of CO₂ to the hundreds (and soon thousands) of concrete plants using our technologies. And so, when working with these key supply chain partners, we go with the best available CO₂ that they can reliably provide to our plants. 

Second, the source. When multiple sources of CO₂ are available, CarbonCure and our partners choose the CO₂ with the biggest climate impact. As mentioned before, carbon removal is our North Star. This means that we prioritize atmospheric CO₂ (biogenic, waste biomass and DAC) wherever possible. Frameworks like biomass with carbon removal and storage (BiCRS) and bioenergy with carbon capture and storage (BECCS) provide guidance on how to best leverage photosynthesis, and the resulting biomass, to draw down CO₂ from the atmosphere and permanently store it.

When atmospheric CO₂ isn’t available, CarbonCure seeks out captured waste CO₂ from industrial processes. This includes sources like hydrogen, ammonia and chemical production, each of which represent important global industries as well as large sources of global greenhouse gas emissions. While we don’t consider it carbon removal, point-source capture from these industries can be an important tool for achieving further emissions reductions beyond just the capture, if the CO₂ is utilized in a permanent manner that cuts emissions.

Although CarbonCure avoids the utilization of geological well-sourced CO₂ (i.e., fossil fuels) in concrete whenever possible, there have been instances where this CO₂ was the only available alternative in a market. In these cases, we do not consider any CO₂ to have been mineralized, as the carbon is simply reintroduced back into the slow carbon cycle where it belongs. Beyond this, we apply an additional penalty to the carbon savings associated with the resulting cement cut to account for the impact on net emissions and to ensure that we heavily prioritize waste CO₂ whenever possible. 

As the supply of captured CO₂ increases and more technologies are brought to market, we also aim to seek out those that offer additional opportunities for positive climate impact. This might include capture from green hydrogen produced with waste feedstocks. Or it might include methods that further expand our impact in the built environment, such as capturing emissions from a building’s boiler, or from cement kilns, or in transportation, such as capture from a truck’s exhaust. When paired with CarbonCure’s technologies, these frontier technologies can multiply their climate impact and further reduce global greenhouse gas emissions.

Third, the cost. For our technologies, CO₂ is the key input, and even though the CO₂ we utilize has a strong climate impact and is often from waste sources, it still comes with a financial cost. 

CO₂ sourced on the industrial market can cost anywhere from $150 to $1000 per metric ton, depending on the source, the state of supply chains and the specific geography. In order to scale our technologies and help decarbonize the built environment, it is crucial to balance the cost of a metric ton of CO₂ from a given source with the potential climate impact of that CO₂. 

Luckily, many of the most promising emerging technologies are rapidly expanding and moving down the cost curve, meaning that CarbonCure and our partners can focus on the beneficial reuse of captured CO₂ in concrete and the construction of a greener built environment across the globe, rather than on the cost of CO₂ in the market.

What’s next?

As CarbonCure scales globally, we will continue to work closely with partners to help source atmospheric CO₂ and permanently store it in concrete. We are building the global infrastructure for permanent CO₂ storage in a hard-to-decarbonize sector, and as DAC and BiCRS come online, we look forward to building innovative partnerships to pull as much CO₂ from the atmosphere as possible, as quickly as possible, and to store it all around us in the built environment. 

To learn more about CarbonCure’s technologies, our credits or our climate impact, reach out to carboncredits@carboncure.com.

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