The Relae Blog

Key Takeaways

• Emissions cuts alone are not happening fast enough to meet global climate goals. Direct air capture (DAC) removes carbon dioxide (CO₂) that is already in the atmosphere. It has become one of the fastest-growing carbon removal approaches even as it stays capital-intensive.
• DAC's core advantage is flexibility. Because the atmosphere fully mixes within about two weeks, a DAC facility can be sited almost anywhere with clean power and CO₂ storage and still deliver the same climate benefit.
• DAC investment has grown to roughly US$2.2 billion across 37 specialized companies since 2021. Per-tonne costs (currently US$500–1,000 or more) remain the technology's central barrier to scale.
• US federal support for DAC is still unsettled. The US Department of Energy cut its regional DAC hub program from a planned US$3.5 billion to roughly US$1.2 billion between October 2025 and April 2026. This is a signal that deployment funding, not the underlying science, is DAC's biggest near-term risk.

What Is Direct Air Capture?

Direct air capture (DAC) works by sucking in air, filtering it to remove CO₂ that has built up over time and still sits in the atmosphere. To be effective, DAC must draw a lot of air into separating equipment like filter banks or cooling towers. This is similar to the small-scale systems that have scrubbed CO₂ from air in spacecraft and submarines for decades. From there, CO₂ filtering typically involves a chemical process that binds the CO₂ for release later. While the most commonly used chemical compounds in this process are liquid solvents or solid sorbents, other chemical, electrical, and physical processes could also work.

After the filtering process, the captured CO₂ is usually stored in one of two ways. The most important is geological storage, which keeps CO₂ out of the air and oceans indefinitely in deep geological formations (typically a mile down or more) and offers the clearest climate benefits. The second is storing the CO₂ in products like concrete, which offers clearer commercial benefits. A new generation of mineralization projects is expanding this second pathway, turning captured CO₂ into building materials rather than only storing it underground. In addition, CO₂ can be recycled into fuels and chemicals, which prevents net-new CO₂ from being released but does not count as a carbon removal solution since these materials are eventually used, releasing the captured CO₂ back to the atmosphere.

The Advantages of Direct Air Capture

DAC has many advantages as a CO₂ removal approach. First and foremost, it's scalable. In effect, there are no practical limits to our ability to scrub CO₂ from the sky or store it in deep geological formations around the world. This means scaling can be fast and removals profound.

It's straightforward. The devices remove CO₂ from the air, a meter measures it, and operators store and monitor that CO₂. It's clearly additional (meaning it only happens with financial and human intervention), easily verified, and durable (stored for many hundreds of years or more), meeting the bar set by our own Criteria for High-Quality Carbon Dioxide Removal.

It has a small physical footprint. Typical DACe systems do the carbon removal work of trees with 1,000–2,000 times less space. This leaves more room for conservation, agriculture, rewilding, and other important work.

It can be done anywhere with low-carbon energy and CO₂ storage options. Globally, our atmosphere mixes fully every two weeks, meaning that CO₂ released in China or Australia arrives over the US (and vice versa) in this amount of time. Because of this, DAC facilities can be sited anywhere and still have a climate benefit—as long as there is sufficient clean energy available and options for CO₂ storage or use are nearby. This reduces competition for land and provides opportunities for economic development in regions with the right resources.

Finally, and most critically, DAC is a backstop technology. While reducing emissions remains the top priority, there are certain types of emissions that are either very hard or very expensive to abate. The last fraction of hard-to-abate emissions can be managed through DAC, effectively capping global costs to reach net-zero emissions. In fact, the more rapidly DAC scales and deploys, the less total energy and cost are needed to achieve key climate goals.

Challenges and Concerns of Direct Air Capture

Like all climate mitigation approaches, DAC has challenges. The primary challenge today is cost. Today's large-scale systems cost roughly US$500–1,000 or more per tonne of CO₂ removed, depending on the technology and site, though several developers are targeting US$100–150 per tonne over the next 10 years. Although the costs will come down over time through deployment and wider adoption, today's high costs are a barrier to investment and deployment.

Another challenge is around the energy requirements associated with DAC. Pulling one million tonnes per year of CO₂ out of the air requires roughly 200–300 megawatts of zero-carbon energy (a combination of heat and electricity). Given the limited supply of zero-carbon energy available today, there is a valid question about whether this is the best use of that resource today.

Finally, there is the question of environmental risks and community burdens of DAC. Experience to date suggests that the total environmental burdens and consequences of this pathway are among the lowest of any clean energy and climate technology. But since DAC systems involve heavy equipment and chemicals, questions about the full environmental risks and burdens to communities remain, especially given its limited commercial deployment. Although most DAC systems will be sited in remote locations, not near communities, and pose no serious environmental risks, reasonable concerns must be addressed before permitting and building future DAC projects.

Why the Excitement Now?

Although current climate science and added urgency from organizations like the Intergovernmental Panel on Climate Change (IPCC) have driven interest in DAC, other important advances have fed broad interest and excitement about its potential. Since 2017, DAC technology has matured greatly, including the deployment and operation of many projects around the world. Costs have dropped, new pathways have opened, and private investment in DAC-specific companies has reached roughly US$2.2 billion across 37 companies since 2021. 

Two large facilities illustrate where deployment stands today. Climeworks' Mammoth plant in Iceland has been operating since May 2024, although not at full capacity. Occidental's Stratos plant in Texas remains delayed past its most recent 2026 second quarter target due to a component issue, with no confirmed new startup date as of this writing. Both facilities carry substantial commercial offtake agreements from aviation, energy, insurance, and tech companies, agreements that continue to hold even as construction timelines have slipped.

In part, interest results from new policy advancements. In the US, the Inflation Reduction Act's 45Q tax credit, maintained under the 2025 One Big Beautiful Bill Act, currently provides US$180 per tonne for DAC paired with dedicated geologic storage, with added parity for utilized CO₂. The Department of Energy's Regional Direct Air Capture Hubs program, originally planned at US$3.5 billion, was cut back sharply in an October 2025 review. It was then partially restored in April 2026 when the Department of Energy confirmed its two flagship projects, Project Cypress in Louisiana and the South Texas DAC Hub, would proceed. The program's total is now expected to be near US$1.2 billion. In addition, California has amended its Low-Carbon Fuel Standard to allow DAC as a compliance mechanism, and the US Department of Energy has explored a pilot program to purchase valid, durable carbon dioxide removal, including DAC. Recently, the Carbon Dioxide Removal Leadership Act was introduced to Congress, which would require the Secretary of Energy to remove CO₂ directly from ambient air or seawater.

Other programs around the world reflect this growing interest. In the UK and EU, governments have promised CO₂ removal purchases this decade, which will likely include DAC. Research programs have begun in Canada, the UK, Germany, Japan, and China. Developing nations increasingly see DAC as a potential new industry and hope to take advantage of their natural resources to expand energy access while being paid to remove CO₂ from the air and oceans.

The Future of Direct Air Capture

I'm pleased to have played a small role in DAC's new prominence. I've had the good fortune of being at DAC project groundbreakings and ribbon cuttings, led the first-ever government grants program for DAC, worked with scientists to develop new DAC technologies, published analysis over a decade ago on the need for DAC, and testified before the US Congress on the benefits and needs of DAC on three separate occasions. Based on my experience in DAC over the last 16 years, I believe that smart investment, policy, deployment, and community engagement will convert the promise of DAC into thousands of projects. These projects will help avoid the worst outcomes of climate change and restore some natural balance to the world. With federal support now concentrated on fewer, better-resourced flagship projects, rather than spread across two dozen early-stage hubs, the DAC field is being pushed toward fewer high-profile delays and more repeatable, bankable deployments.

Frequently Asked Questions

How does direct air capture differ from capturing carbon at an industrial site? 

Industrial, or point-source, capture removes CO₂ at a smokestack, where concentrations are high. Direct air capture removes CO₂ that is already spread throughout the open atmosphere. DAC facilities can operate almost anywhere with available clean power and storage, not only next to a specific emitter.

Is direct air capture actually operating today, or is it still experimental? 

Direct air capture is operating today; it is not just experimental. Climeworks' Mammoth plant in Iceland has been running since May 2024, and dozens of smaller facilities are active worldwide. However, the largest US projects, including Occidental's Stratos plant in Texas, are still working through startup delays. Once it begins operating, DAC will be fully commercial, although limited in deployment.

How much does it cost to remove one tonne of CO₂ with direct air capture? 

Current large-scale direct air capture systems cost roughly US$500–1,000 or more per tonne of CO₂ removed, depending on the technology and facility site. Several developers are targeting costs of US$100–150 per tonne later this decade, though that has not yet been demonstrated at commercial scale and is likely to take 10 years or more to achieve

Does using direct air capture reduce the need to cut emissions? 

No. Direct air capture is a backstop for emissions that are difficult or costly to eliminate outright, not a substitute for cutting emissions in the first place. Reducing emissions remains a priority; DAC addresses both what is left over (residual emissions) and what’s already in the air and oceans.

Key Takeaways

• Cement is the key ingredient in concrete and is responsible for more than 80% of concrete’s emissions. Cement’s GHG emissions are the primary technical challenge in decarbonizing an industry that accounts for over 8% of annual global greenhouse gas emissions. 
• The global market for low-carbon concrete is constrained by the slow deployment of breakthrough technologies, yet demand from major buyers such as hyperscalers, developers, and infrastructure investors is accelerating. This mismatch between demand and supply is creating a new market mechanism: environmental attribute certificates (EACs) for building materials. 
• EACs represent the climate benefits of low-carbon materials and can be traded separately from the physical product. These certificates, when backed by robust technical diligence, offer a near-term funding mechanism to accelerate decarbonization across the cement and concrete supply chain.

The AI Boom Meets an Industrial Reality

As the market for AI infrastructure expands, data center construction is accelerating—and with it, demand for concrete, one of the most carbon-intensive materials in the built environment. For both builders and material suppliers, the embodied carbon of cement and concrete is under a microscope due to its significant climate impact. Hyperscalers, like Microsoft and Meta, have 2030 targets that far outpace the concrete industry’s readiness to provide near-term low-emissions materials. 

This piece explores why cement and concrete decarbonization is so challenging and how credible, high-quality EACs can help bridge the ambition gap. 

Cement and Concrete: An Important Distinction 

These two terms are often used interchangeably, but they are not the same—and the distinction matters for decarbonization strategy. Cement is the reactive ingredient in concrete, acting like an egg in a cake batter. Concrete itself is a blend of cement, aggregates (like sand and gravel), and water (the batter overall). While concrete is widely used and often seen as the emissions culprit, it is actually cement—just 15% of the mix by volume—that is responsible for more than 80% of concrete’s lifecycle carbon emissions. 

Why Is Concrete so Hard to Decarbonize?

Concrete is the second most-used material on Earth after water. Despite emitting only ~0.13 kg of CO₂ per kilogram, its sheer scale gives it an outsized climate impact—contributing around 8% of global CO₂ emissions. Yet decarbonization has been slow, held back by technical, structural, and accounting challenges across a complex supply chain. 

The Supply Chain Behind Concrete’s Carbon Footprint

To understand why decarbonizing concrete is so difficult, it’s essential to understand how it’s made and what drives its emissions. Three factors explain much of the difficulty: 

• Cement is made in an emissions-intensive process. Cement is produced by heating limestone to extreme temperatures (~1450 °C) to create clinker, a reactive material that binds sand and aggregates into concrete. This energy and carbon-intensive process is where the majority of the emissions occur. 
• Concrete is made to order. Concrete is a blend of cement, aggregate, and water. It is made to order at local batch plants and poured on-site or used in precast molds, with mix designs tailored to specific compressive strength and durability requirements. 
• The supply chain is decentralized and performance-driven. Because concrete mixtures must meet application-specific performance requirements, low-carbon innovations are limited to those that do not decrease product quality and performance at any point in the value chain. 

This layered supply chain, from kiln to batch plant to job site, means decarbonization strategies must be compatible with local infrastructure, material availability, and performance needs. There is no single lever to pull. 

Clinker Is the Main Emissions Driver

Clinker production alone accounts for the majority of cement’s emissions, due to the chemical process (calcination) that converts limestone into lime and releases CO₂. Not only does calcination directly produce CO₂, but the combustion of fossil fuels used to heat the kiln adds to the emissions of the overall process. 

Low-Carbon Concrete Technology: Invented, Not Yet Deployed

Six promising technologies are in development to address cement and concrete emissions, including: 

1. Carbon Capture and Storage (CCS): CCS can be retrofitted to capture the fuel and process emissions from clinker production, delivering nearly complete decarbonization of the cement manufacturing process. CCS can be combined with electrification or fuel switching to deliver deeper decarbonization
2. Supplementary cementitous materials (SCMs): SCMs offer two key benefits: they can partially replace conventional cement in concrete mixtures, and certain SCMs react with CO₂ from industrial or atmospheric sources to enable durable carbon storage.
3. Electrification: Electrifying kiln heating systems can reduce emissions from fossil fuel combustion during clinker production. When powered by low-carbon electricity, this approach lowers the carbon intensity of cement manufacturing while maintaining the high temperatures required for clinker formation.
4. Fuel Switching: Natural gas, biomass, and renewable natural gas are low carbon-intensity fuels that can replace the higher-emitting coal and refuse derived fuel that usually drive the clinker production process. Unlike electrification, some alternative fuels can be used as 'drop-in' replacements in existing equipment. 
5. Synthetic and recycled aggregates: Alternatives to traditional gravel and crushed stone, made from waste materials or industrial byproducts, which can lower emissions and reduce resource extraction.
6. CO₂ curing: A process where concrete is cured with captured CO₂ instead of air, helping lock carbon into the material and partially offsetting upstream process emissions.

Each solution faces deployment challenges, from raw material availability and geographic constraints to cost, performance certification, and integration with legacy infrastructure. 

Few decarbonization strategies have reached industrial scale today, but these strategies are being piloted and demonstrated, and given targeted support, some have the potential to significantly decarbonize the future of the industry. 

The Gap Between Targets and Real Market Capacity

Hyperscalers, utilities, real estate developers, and other large organizations with ambitious scope 3 targets are looking to significantly reduce the embodied carbon throughout their supply chain. However, the current supply of deeply decarbonized cement and concrete is insufficient to support these targets through direct procurement alone; the low-carbon material simply does not exist at the required volume or in the right geographies. In some cases, pilot plants produce too little material to meet large-scale demand, while projects capable of larger volumes may not yet be located in regions where interested buyers are concentrated.

In this context, EACs offer a flexible mechanism to fund innovation and bridge the gap. By unbundling climate attributes from physical materials, near-term obstacles, such as geographic availability, can be overcome while channeling capital toward scalable and catalytic solutions. 

When backed by rigorous life cycle assessments and high-quality, transparent traceability standards, EACs can provide the financial bridge for truly innovative suppliers to invest in the capital solutions required to decarbonize cement and concrete. EACs can serve a catalytic role to support scalable strategies and help ensure that first-of-a-kind facilities are built, and direct procurement of low-carbon concrete is increasingly feasible in the years to come.

How Environmental Attribute Certificates Work in Cement and Concrete Markets

EACs translate emissions reductions from low-carbon cement and concrete production into climate attributes that can be purchased separately from the physical material. Instead of requiring buyers to procure low-carbon concrete directly from a specific supplier site, EACs allow the climate benefit associated with that production to be transacted independently through a book and claim model.

In practice, a producer implements a verified emissions reduction intervention, such as reducing clinker content through supplementary cementitious materials, installing carbon capture at a kiln, or deploying alternative cement chemistries. The resulting emissions reductions are quantified through life cycle assessment and product-level disclosures such as Environmental Product Declarations. Verified reductions can then be converted into certificates representing the climate benefit of that lower-emissions production.

Buyers can purchase these certificates to support the deployment of low-carbon cement and concrete technologies while making progress toward embodied carbon reduction targets. In this way, EACs provide an early demand signal and a revenue stream that can help producers finance capital-intensive decarbonization investments across the cement and concrete supply chain.

What This Means for Suppliers and Buyers

Whether you are procuring concrete or producing it, EACs are only one part of a broader decarbonization strategy. Navigating this space requires decisions at the intersection of technical feasibility, GHG accounting, and capital strategy. Key considerations include: 

• GHG accounting and reportability: Life cycle assessments, Environmental Product Declarations, and other product-level attributes must be tracked and transacted with high integrity. Buyers should report their EAC activities responsibly, especially in the current absence of formal standards and guidance.
• Procurement alignment: EAC buyers must ensure purchased certificates reflect equivalent performance grade materials to what was directly procured for structural applications.
• Monetization pathways: Book-and-claim EAC models offer producers a way to fund capital-intensive decarbonization upgrades while giving buyers a credible way to meet interim scope 3 goals. EAC transactions can take many forms and should be designed thoughtfully to minimize risks such as double counting.

Frequently Asked Questions

What is low-carbon cement, and how does it work?‍

Low-carbon cement reduces emissions by replacing traditional clinker with supplementary cementitious materials (SCMs), switching to cleaner fuels, electrifying kilns, or capturing CO₂ at the point of production. Because cement is responsible for more than 80% of concrete's lifecycle emissions, interventions targeting clinker production deliver the greatest climate impact. Most approaches are technically proven at smaller scales but have not yet reached the industrial volumes needed to meet mainstream demand.

How do EACs for cement and concrete compare to direct procurement of low-carbon materials?‍

Direct procurement means physically buying low-carbon concrete from a supplier, which requires that product to exist at conditions that often can not be met today. EACs decouple the climate benefit from the physical material, allowing buyers to fund verified emissions reductions across the supply chain even when direct sourcing isn't feasible. Both approaches can count toward scope 3 targets, but EACs offer more flexibility in the near term while the low-carbon materials market matures.‍

Is low-carbon concrete proven and available at scale today?‍

The core technologies for decarbonizing cement and concrete are technically demonstrated, but most have not reached commercial scale. Supply is geographically concentrated and insufficient to meet the volume demands of large buyers like hyperscalers, utilities, and real estate developers. This gap between technical readiness and market availability is precisely what makes EACs a valuable bridging mechanism right now.

What should a company look for when evaluating EACs for cement and concrete?‍

‍High-quality EACs should be backed by rigorous life cycle assessments and transparent traceability standards that tie the certificate to a specific, verifiable emissions reduction intervention. Buyers should also confirm that the certificates represent materials with equivalent performance grades to what they are directly procuring for structural applications, and that accounting practices minimize risks like double counting. Working with a technically credible advisor to evaluate EAC quality is essential, since the market currently lacks formal standards and guidance.

How Relae Can Help Decarbonize Cement and Concrete 

Decarbonizing cement and concrete is both a technical and a strategic challenge. Relae brings integrated expertise across geochemistry, life cycle assessment, carbon accounting, and industrial decarbonization strategy to help buyers and producers navigate the complex path to decarbonization. Relae works directly with producers developing low-carbon cement and concrete technologies and with global buyers seeking credible pathways to address embodied emissions in construction. Our team combines industrial decarbonization engineering, geochemical expertise, and carbon accounting to evaluate emerging EAC frameworks and ensure they deliver real climate impact.

• EAC advisory for buyers: Relae helps buyers procure high-quality EACs through criteria development and in-depth technical diligence of EAC offerings across a range of low-carbon commodities, supporting purchased certificates that reflect genuine, verifiable climate impact. 
• EAC advisory for suppliers: Relae helps producers design high-quality EAC interventions and assess potential EAC claims throughout the supply chain, informed by technical assessment, book-and-claim systems, and market landscaping.
• For both: Relae’s levelized cost of carbon abatement tooling provides custom modeling to assess trade-offs across cement and concrete decarbonization pathways, helping ensure that every dollar of climate spend goes further.