Utilization of Captured CO2

Turning waste into a resource

Most DAC companies pursue geological storage currently, however, creating a profitable economy for captured CO2 is an emerging focus to offset the high cost of DAC. Both the direct utilization of captured CO2 and its use as a feedstock to manufacture other products are growing. Explore several methods of DAC-sourced CO2 utilization below and the companies involved.

Why Carbonate Materials?

Cement production generates a tremendous amount of CO2, amounting to approximately 8% of global anthropogenic CO2 emissions, and cement production is estimated to increase 12-23% by 2050. To lower emissions, the cement industry incorporates supplementary cementitious material (SCM), wherein a portion of the cement used to make concrete is replaced with SCM. CaCO3 (synthetic limestone) is especially promising in this regard and enhances the properties of cement and concrete in several ways including:

CaCO3 can accelerate the hydration of cement, leading to earlier strengthening and improved concrete durability. Improved strength and stiffness likewise decrease the amount of cement required for building, lowering costs.
CaCO3 can also provide better packing density in concrete, decreasing its permeability.
CaCO3 improves the workability of concrete, facilitating a long enough work time so that it can be pushed and shaped more easily.

Carbonates formed from atmospheric carbon can achieve durable CO2 removal when incorporated into concrete building materials. Several other industries including paper production, plastics & polymers, paints, water treatment, and agriculture are also markets for CaCO3.

CO2 to Product

Carbon dioxide reacts directly with sources of alkalinity (e.g., NaOH, KOH, CaOH) to form the corresponding carbonate materials (e.g., Na2CO3, K2CO3, CaCO3), either in solution or as a solid. Alkaline materials must be sourced or generated to enable continuous production. Where NaOH and KOH are used as sorbents, an additional step is often incorporated to convert Na2CO3 and K2CO3 to CaCO3 and/or MgCO3, as the latter are generally preferred products.

Summary

Utilization Approach

Feedstock

Largest Market

Cement Production

Current CDR via DAC (estimate)

500–1,000 tCO2/y

Carbonate material synthesis integrates especially well with liquid electrochemical DAC and solid DAC using metal oxide sorbents (i.e. CaO/Ca(OH)2). Electrochemical DAC frequently utilizes the same alkalinity sources (e.g., NaOH, KOH) to capture CO2 as carbonate intermediates, which are converted back to hydroxide when the CO2 is released. With a continuous supply of alkalinity, CO2 can be stored as carbonates and avoid regeneration. As an example, Capture6 uses water desalination to continuously produce an alkaline stream, primarily NaOH, from brine via electrodialysis, then uses it to capture CO2 and generate carbonate materials.

In solid DAC using metal oxides, the capture step forms solid carbonate materials (primarily CaCO3) directly. The subsequent process of heating carbonate materials to over 600 °C for regeneration and CO2 release is very energy intensive, so some companies are avoiding regeneration by marketing the carbonate materials and replenishing their adsorbent supply with each capture cycle. For example, Carbon Reform is operating several pilots utilizing this approach to capture CO2 and supply CaCO3.

Summary of Activities

View DAC technology producers who are pursuing carbonate material synthesis. Sort DAC deployments by company, scale, start of operations, and more. Because DAC is a rapidly evolving industry, this list may not be exhaustive.*

To focus this analysis, only DAC technology producers pursuing carbonate materials are reviewed here. Nonetheless, this approach contains significant overlap with electrochemical CDR methods that pre-process industrial waste such as basic oxygen steelmaking (BOS) slag to generate alkalinity sources for point source and atmospheric CO2 capture. Companies such as Paebbl and O.CO. Technology developing reactors that form carbonate materials using concentrated CO2 are not explicitly reviewed here, but are noted to have formed partnerships with DAC companies as CO2 providers (see below).

* Due to uncertain funding, plans for most DOE-funded DAC Hubs are not included in this analysis.

Why e-Fuels?

Drop-in fuel replacements. In the near-term, lowering the carbon-intensity of current fuels is an impactful way to support the transition to net zero while continuing to use current engines, fuel distribution, power generation, and other infrastructure that would be incredibly challenging to suddenly overhaul. CO2-derived fuels have the potential to fill this role by replacing fossil fuels.

Some sectors are also stubbornly reliant upon hydrocarbon fuels because no suitable alternatives currently exist. In aviation, for instance, alternatives to kerosene like batteries, hydrogen, and ammonia fuel do not offer suitable energy density for medium- and long-haul travel, or are limited by space. In these cases, producing carbon-neutral fuels is a more attainable goal.

Some of the most exciting e-fuels are:

Methane - Methane combustion accounted for approximately 21% of global carbon emissions in 2025. Synthetic methane is a drop-in replacement for the widespread current applications of natural gas, including electricity generation, heating, and transportation. If synthesized using renewable energy, synthetic natural gas can also store that energy long-term for use in power generation during periods of intermittent access to renewables.
Methanol - Shipping is heavily reliant on heavy fuel oil, and as such is also responsible for about 3% of global greenhouse gas emissions. Synthetic methanol is a promising, cleaner marine fuel than heavy fuel oil and is likewise easier to handle and store on ships than liquified natural gas.
Kerosene - Burning jet fuel accounts for about 3% of global CO2 emissions, with additional climate impact from non-CO2 effects like contrails. Consumption of jet fuel is expected to more than double by 2050. Meanwhile, a group of nearly 300 airlines has committed to zero carbon emissions by 2050. Drop-in sustainable aviation fuel (SAF) is the most scalable option to decarbonize the industry in this timeframe.

Over the last few decades, synthetic fuel production derived from CO2 emissions has grown into a large industry. Fuel production from CO2 is largely tied to industrial flue gas streams with high CO2 concentrations where associated carbon capture technologies are cheap and effective, making fuel production more affordable. SAF production currently costs about $9 per gallon, which is approximately four to six times the price of fossil kerosene.

Inevitably, as synthetic fuels are consumed, industrially-sourced CO2 is released into the atmosphere. As DAC technology has rapidly developed in the last decade, new and improved methods are lowering energy and cost requirements, which has motivated many companies to consider integrating DAC with e-fuel synthesis to produce truly carbon-neutral fuels. Many DAC technology developers are now integrating in-house e-fuel production with their DAC processes or have formed partnerships to supply CO2 to synthetic fuel producers.

Summary

Utilization Approach

Feedstock

Largest Markets

Energy,

Aviation,

Shipping

Current CDR via DAC (estimate)

2,000–3,000 tCO2/y

CO2 to Product

Methane - Methane is synthesized from CO2 and H2 via the Sabatier process in which they are heated (approx. 400 °C) under pressure (approx. 30 bar) and in the presence of a metal catalyst, forming methane and water. The process also likely involves forming CO and H2O via the Reverse Water-Gas Shift reaction, then methanation of CO.

Methanol - Methanol synthesis from CO2 involves a combination of hydrogenation reactions. At intermediate temperature and high pressure (250–300 °C, 50-100 bar), CO2 is catalytically hydrogenated to form CH3OH directly, or forms CO and H2O via the Reverse Water-Gas Shift reaction. CO is then hydrogenated by additional H2 to form CH3OH.

Kerosene - SAF is primarily produced via the Fischer-Tropsch (FT) or the alcohol-to-jet processes. In the former, CO2 reacts with H2 catalytically at high temperature (approx. 750 °C) and is converted to CO via the Reverse Water-Gas Shift reaction. Then, CO reacts with additional H2 at high temperature and pressure (200–350 °C, 20–30 bar) to form a mixture of long-chain hydrocarbon products (jet fuel is C8-C16) via the FT reaction from which kerosene is eventually isolated. In the alcohol-to-jet process, light alcohols, typically methanol, are dehydrated to form olefins at high temperature (400-500 °C) then oligomerized and hydrogenated at intermediate temperatures and high pressures (100–250 °C, 20–50 bar) to produce jet fuel.

In all cases, hydrogen is a crucial ingredient. Omitting DAC, the most cost- and energy-intensive step in e-fuel synthesis is H2 production, which typically occurs via alkaline water electrolysis and requires substantial electricity (43–73 kWh/kgH2). Notably, a leading approach in liquid electrochemical DAC uses alkaline electrolysis to capture CO2 and co-produce H2. Some DAC companies like Greenlyte are seizing the opportunity to reuse this H2 for fuel production alongside DAC. Regardless of the product, the cumulative energy required for e-fuel production is substantial, thus the carbon intensity of e-fuels is heavily dependent upon the electricity source.

Summary of Activities

View DAC technology producers who are pursuing e-Fuels synthesis. Sort DAC deployments by company, scale, start of operations, and more. Because DAC is a rapidly evolving industry, this list may not be exhaustive.*

To focus this analysis, only e-Fuels producers utilizing DAC-sourced CO2 are considered. However, e-Fuel synthesis from other CO2 sources, particularly industrial flue gas streams, is a much larger field.

* Due to uncertain funding, plans for most DOE-funded DAC Hubs are not included in this analysis.

Why Greenhouses?

Indoor farming operations generally target elevated CO2 concentrations between 800–1200 ppm (approx. 430 ppm in air) for optimal plant growth. As crops consume CO2 its concentration drops in the enclosed spaces. Under about 250 ppm, plant growth will slow or stop, so a continuous supply of CO2 is required. Currently, indoor farming facilities commonly rely on burning fossil fuels to provide CO2 enrichment. Others purchase compressed tanks, however the production and transportation of compressed CO2 causes additional environmental impacts.

Microalgae cultivation is an attractive biogenic CDR method that uses fast-growing single-celled microorganisms to absorb CO2 from the atmosphere or industrial waste streams. Microalgae have a high photosynthetic efficiency, relative to terrestrial plants, making them an especially effective carbon sink. As in indoor agriculture, photo-bioreactors are generally operated under an elevated CO2 concentration (1–10% CO2) for optimal microalgae growth. The biomass can then be processed to create biofuels, fertilizers, animal feed, and other products. DAC-sourced CO2 can be integrated into these products if it is used to cultivate the microalgae. Analysis has shown that integrating DAC with biofuel production in a photo-bioreactor provides cost and greenhouse gas emissions benefits, relative to current technologies.

The present demand for CO2 in greenhouses provides a clear incentive to integrate carbon capture with these industries. Besides supporting sustainable agriculture and microalgae production, this method of CO2 utilization also does not need to meet the purity (>70%) required for economical geological storage, so methods of DAC that do not currently meet this requirement, such as pressure gradient-based membrane separations, can be integrated. On the other hand, less modular DAC methods requiring large facilities and/or cost-intensive equipment like calciners and slackers may be less practical for smaller, distributed greenhouses. Most DAC companies pursuing greenhouse utilization of CO2 are developing solid, low-temperature DAC systems.

Summary

Utilization Approach

Direct use

Largest Markets

Agriculture,

Algae

Current CDR via DAC (estimate)

100–500 tCO2/y

Summary of Activities

View DAC technology producers who are pursuing greenhouse utilization. Sort DAC deployments by company, scale, start of operations, and more. Because DAC is a rapidly evolving industry, this list may not be exhaustive.*

* Due to uncertain funding, plans for most DOE-funded DAC Hubs are not included in this analysis.

Why Chemicals?

In addition to e-fuel production, a handful of chemical industries use CO2 as a feedstock for commodity chemical synthesis, including fertilizers (urea), solvents (carbonates), and polymers precursors (polycarbonates). However, other chemical industries could utilize CO2 as a raw material. The synthesis of e-fuels using DAC-sourced CO2 is the most common use of CO2 as a feedstock to produce other chemicals, nonetheless, a small number of DAC companies are pursuing alternative products.

Sulfuric acid - Travertine has developed a unique electrochemical process that combines CO2 and gypsum waste from fertilizer and mining industries to synthesize sulfuric acid alongside carbonate materials (CaCO3) and green hydrogen. Sulfuric acid is the most-produced chemical globally with widespread uses including fertilizer production, chemical manufacturing, and metal refining. Carbonate materials are used to decarbonize cement production and green H2 is a sustainable fuel and feedstock.

Solid carbon products - Carbon Utility and OBRIST Group are pursuing carbon fiber and graphite, respectively, as co-products alongside methanol production. The solid products are formed from excess CO2 not used to synthesize the fuel. Carbon fiber is used to make strong and lightweight composite materials for numerous applications such as aircraft manufacturing. Graphite is primarily used in electric vehicle battery production and as a component of refractory materials used in high-temperature industrial environments like steelmaking.

Formic acid - RedoxNRG produces formic acid electrochemically using CO2 captured by the company's DAC technology. RedoxNRG intends to use formic acid as a fuel source in formic acid fuel cells. Currently, formic acid is primarily used as a preservative and antibacterial agent in livestock feed, as well as in the textile and chemical manufacturing industries. A front end engineering design study investigated the integration of Aircapture's DAC technology with OCOchem's electrochemical formic acid synthesis reactor and waste heat from a Nutrien fertilizer manufacturing facility in Kennewick, WA. Life-cycle analysis of the process predicted a net negative global warming potential when powered by renewable energy sources, while economic analysis highlighted high electrical requirements and capital costs of formic acid production.

Glycerol carbonate - Glycerol carbonate is used as a green solvent and polymer precursor in the chemical industry and as an additive in cosmetic products, among other applications. Glycerol carbonate has also been proposed as a sustainable fuel additive. In a future deployment, Atmosfuture plans to produce glycerol carbonate alongside e-Fuels.

Summary

Utilization Approach

Feedstock

Largest Market

Chemical Industry

Current CDR via DAC (estimate)

50–100

tCO2/y

Summary of Activities

View DAC technology producers who are pursuing chemical manufacturing. Sort DAC deployments by company, scale, start of operations, and more. Because DAC is a rapidly evolving industry, this list may not be exhaustive.*

* Due to uncertain funding, plans for most DOE-funded DAC Hubs are not included in this analysis.

Why Concrete Injection?

Calcium silicates are the main components of Portland cement. When mixed with water they form calcium silicate hydrate (C-S-H) crystallites, which give concrete its strength, as well as Ca(OH)2. The latter naturally reacts with CO2 to form CaCO3 and is the basis of most solid high-temperature DAC technologies. C-S-H is also capable of reacting with CO2 directly to form CaCO3. For this reason, concrete structures absorb CO2, however, absent substantial CCUS during cement production, this amount is far smaller than the associated emissions of producing the concrete.

Injecting concrete with CO2 utilizes these reactions to accomplish durable sequestration in building materials. Carbonation of hardened concrete suffers from poor diffusion of CO2 through the solid (penetrating only several millimeters) without added pressure (1–5 bar CO2), but that is costly and logistically challenging. On the other hand, injecting CO2 alongside water during concrete mixing prior to casting results in a greater volume of carbonated concrete while avoiding impractical equipment. For example, CarbonCure has developed a technology that injects a precise quantity of CO2 from a tank stored on-site into hoppers or central mixers of cement plants. By retrofitting their technology with current plants, CarbonCure has licensed its technology to over 800 producers in 35 countries. The company partnered with Heirloom to utilize CO2 from their California DAC pilot for concrete injection.

Nanoparticles of CaCO3 that form via CO2 injection impart similar benefits as CaCO3 added to cement as supplementary cementitious material (SCM). Most notably, CaCO3 can accelerate the hydration of cement by nucleating C-S-H crystallites, leading to earlier strengthening and improved concrete durability. Similarly, CaCO3 precipitations form in the pores of curing concrete, which decreases permeability and enhances its early-stage strength. Improved strength and stiffness likewise decrease the amount of cement required for building, lowering costs.

Summary

Utilization Approach

Direct use

Largest Market

Concrete Production

Current CDR via DAC (estimate)

1,000–2,000

tCO2/y

Summary of Activities

View DAC technology producers who are pursuing concrete injection. Sort DAC deployments by company, scale, start of operations, and more. Because DAC is a rapidly evolving industry, this list may not be exhaustive.*

To focus this analysis, only DAC-sourced CO2 used for concrete injection is summarized below. However, utilization of CO2 from industrial waste streams for concrete injection is a larger field.

* Due to uncertain funding, plans for most DOE-funded DAC Hubs are not included in this analysis.