How Direct Air Capture removes CO₂ from our atmosphere

Direct Air Capture (DAC) is a technology that can remove CO2 from the atmosphere and store it permanently in geological formations or use it for various purposes. DAC is a carbon dioxide removal (CDR) method essential for achieving net-zero emissions by 2050 and limiting global warming to 1.5°C. In this article, we will discuss the aspects of DAC.

The technology behind DAC

DAC technologies extract CO₂ directly from ambient air using chemical or physical processes. CO₂ can be captured by contacting air with a liquid solvent (usually amine-based or caustic) or a solid sorbent (such as activated carbon or metal-organic frameworks) that selectively binds to CO₂ molecules. The CO₂ is then released from the solvent or sorbent using heat, pressure, or electricity, resulting in a concentrated CO₂ stream that can be dehydrated and compressed for storage or use.

DAC technology varies depending on the type of solvent or sorbent, the configuration of the contactor (the device that exposes the air to the solvent or sorbent), and the energy source for regeneration (the process that recovers the solvent or sorbent for reuse). For example, some DAC systems use fans to force air through a contactor, while others rely on natural wind or convection. Some DAC systems use low-temperature heat (e.g., waste heat from industrial processes) for regeneration, while others use electricity (preferably from renewable sources) or solar thermal energy.

How DAC can help on the path to net zero

DAC offers a way to remove CO₂ from the atmosphere and account for emissions that cannot be avoided or eliminated, such as emissions from aviation and shipping, cement and steel production, and agriculture. DAC can also be a source of low-carbon or carbon-neutral fuels and chemicals by combining the captured CO₂ with hydrogen produced from renewable electricity or biomass. These fuels and chemicals can be used in sectors that are difficult to electrify or decarbonize, such as aviation, shipping, and plastics.

DAC can also contribute to negative emissions if the captured CO₂ is permanently stored in deep geological formations, such as depleted oil and gas reservoirs, saline aquifers, or basalt formations. Negative emissions are needed to offset residual and historical emissions that have accumulated in the atmosphere over time. According to the International Energy Agency (IEA), DAC could capture nearly 60 million tonnes of CO₂/year by 2030 and up to 1.9 Gt of CO₂/year by 2050 under the net-zero emissions by 2050 scenario.

Where can you find these DAC systems?

DAC plants can be operated anywhere with sufficient space, access to energy and water, and proximity to storage or utilization sites. DAC plants can be modular and scalable, allowing flexibility and adaptability to different environments and conditions. However, some locations offer advantages over others in terms of cost, performance, and environmental impact.

For example, sites with low humidity and high wind speed can increase the efficiency and effectiveness of DAC systems by increasing the contact area and mass transfer rate between the air and the solvent or sorbent. Sites with abundant, low-cost renewable electricity or waste heat can reduce the energy costs and carbon footprint of DAC systems by providing clean and cheap energy for regeneration. Finally, sites with nearby geological storage sites can reduce transportation costs and the risk of CO₂ leakage by minimizing the distance and infrastructure required for CO₂ injection.

Selected actors in the DAC field

• Carbon Engineering ( website ): A Canadian company that uses large fans and chemical processes to capture CO₂ and either produce synthetic fuels or transport it to sequestration sites.

• Climeworks ( website ): A Swiss company that uses modular units and renewable energy to capture CO₂ and either sell it to various markets, such as greenhouses and carbonated beverage producers, or transfer it to geological storage.

• Removr ( website ): A Norwegian company building a solid sorbent carbon removal plant to capture CO₂ from the atmosphere and store it underground.

1PointFive ( website ): An American company that also uses chemical processes to extract CO₂, which is then either used for industrial applications or permanently stored underground.

Summary

Direct Air Capture (DAC) technology has enormous potential to address the urgent need to remove CO₂ from the atmosphere and combat climate change. With its ability to neutralize emissions in challenging sectors, provide low-carbon fuels, and contribute to negative emissions through permanent storage, DAC offers a promising path to achieving net-zero emissions and limiting global warming. As sites, technologies, and key players in the DAC market continue to evolve and innovate, we can look forward to a future where carbon removal becomes a tangible and impactful solution in the fight against climate change.

Freeze Carbon has partnered with DAC projects to support companies on their journey to net zero. 

Here we have summarized the most important elements for DAC .