The impact of climate change is growing each year, and countries worldwide are exploring new and innovative ways to reduce carbon emissions and mitigate the effects of a warming planet. With many unique benefits over other types of carbon removal technologies, direct air capture (DAC) is one of the most promising of these emerging technologies. But what exactly is DAC and how can it be used to help bring the world closer to net-zero carbon emissions? Let’s take a closer look.
What Is Direct Air Capture?
Direct air capture is a potentially groundbreaking carbon removal method that uses chemical reactions to extract carbon dioxide from the surrounding air. CO2 is isolated from other atmospheric components through the strategic deployment of specific chemical agents, allowing for a more targeted approach to carbon capture.
Current DAC technologies typically use either liquid solvents or solid sorbents for this process, both of which are chemicals commonly found in a range of everyday products, such as household soaps and water filtration systems.
After the carbon dioxide is captured from the air, heat is used to facilitate the release of C02 from the solvent or sorbent. This process regenerates the solvent or sorbent so that it can be used in future captures. Some emerging DAC technologies incorporate advanced electrochemical processes, which hold the potential to minimize energy requirements and reduce overall costs associated with the capture process.
Following the extraction process, the captured CO2 can either be used or stored deep underground in specific types of geological formations for sequestration.
Direct Air Capture vs. Carbon Capture
DAC and carbon capture have various similarities, but they work in fundamentally different ways. Carbon capture prevents the release of CO2 into the atmosphere by capturing it, compressing it, and subsequently transferring it through pipelines for storage or other purposes. DAC removes CO2 already present in the atmosphere and can remove CO2 that was emitted several years prior. Carbon capture’s goal is to reduce CO2, while DAC is designed to remove CO2 from the atmosphere.
Once carbon is captured, both technologies undergo a similar process, potentially employing identical equipment for compressing, transferring, and storing the captured carbon. One notable difference is that DAC may recycle the capturing chemical multiple times to repeat the process, whereas carbon capture can utilize each chemical only once.
The two technologies also differ significantly in where they can be used. DAC is incredibly versatile and can be used anywhere. On the other hand, carbon capture technologies are limited to stationary sources of CO2 like power plants and ethanol production plants.
Challenges in Implementing DAC Technologies
DAC holds enormous potential to make a major impact in the fight against climate change. However, several challenges must be overcome before this exciting new technology can reach its full potential.
Cost: Cost is one of the most significant hurdles. DAC costs more per tonne of CO2 removed compared to carbon capture and other emissions mitigation strategies. DAC costs between $250 and $600 per tonne, depending on the technology used, the low-carbon energy source, and the scale of deployment. Reforestation, by comparison, costs less than $50 per tonne.
Maintaining a Well-Rounded Approach: While DAC is promising, it is important to ensure that the focus on DAC does not overshadow critical investments in other mitigation strategies, particularly those aimed at reducing reliance on fossil fuels. The scientific community generally believes that the world must prioritize both carbon removal and reducing emissions at a faster pace and that the amount of carbon removed is directly related to lower emissions.
Government Policies and Regulations: Comprehensive policy frameworks and strong private sector regulations are essential to prevent an over-reliance on carbon removal at the expense of curbing emissions. Recent guidelines from the Science Based Targets initiative emphasize the priority for companies to reduce their emissions by more than 90 percent, relying on carbon removal solely to offset the remaining 5 percent to 10 percent.
DAC and Fossil Fuel Production: Challenges also arise regarding the link between DAC and fossil fuel production, particularly through Enhanced Oil Recovery (EOR) practices, where captured CO2 is used to extract additional oil from depleted wells. While EOR facilitates the permanent sequestration of injected CO2, it inadvertently perpetuates further emissions through increased oil production. This could potentially impede the pace of the global energy transition.
Community Acceptance: Community apprehensions surrounding CO2 pipelines and geological storage are a major hurdle, underscoring the need for stringent safety protocols and environmental considerations. The 2020 CO2 pipeline rupture in Mississippi illustrates the critical need for heightened vigilance and comprehensive regulatory measures to mitigate the risks of transporting and storing large quantities of CO2.
Conclusion
As DAC continues to gain prominence, detailed research and engagement with affected communities will be instrumental in understanding and addressing the potential impacts of these projects, fostering a more informed and inclusive approach to the implementation of DAC infrastructure.