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Direct air capture technology: how to make our future cleaner?
Facing the threat of global warming, scientists and engineers are working hard to find innovative solutions, one of which is direct air capture (DAC) technology. This technology extracts carbon dioxide (CO2) directly from the atmosphere through chemical or physical processes and seeks effective storage solutions. The development of DAC is not only to capture carbon emissions from industrial emission sources, but also to purify the entire environment and reduce the concentration of carbon dioxide in the atmosphere.
Direct air capture technology (DAC) not only captures carbon dioxide already present in the atmosphere, but also achieves negative emissions, which is crucial to combating climate change.
DAC mainly consists of three stages: contact stage, capture stage and separation stage. First, the system uses large fans to transport atmospheric air to the device; then, during the capture phase, the CO2 is quickly combined with the liquid solvent or solid adsorbent; and finally, through the application of external energy, the separation phase removes the CO2 from the solvent or adsorbent. separated from it. Although this process may seem simple, it actually requires a lot of energy and makes the running costs of the DAC escalating.
As of 2023, DAC technology has not yet achieved widespread commercialization and economic benefits, and the cost per unit of captured carbon dioxide is as high as more than $1,000, much higher than the market price. Therefore, the widespread application of DAC still requires policy support and technological innovation.
Many experts predict that if DAC technology can be successfully commercialized, it will have the potential to combat climate change and raise public awareness.
The environmental impact of DAC technology is at the center of discussion. Supporters believe that this technology is an important means to combat global climate change and can help the world achieve the goals of the Paris Agreement; however, opponents say that relying on this technology will cause a waste of resources and may delay attention to emission reduction measures.
In terms of technical approaches, there are many options for capture materials used in DAC, including solid adsorbents and liquid solvents. Many commercial DAC solutions use amino compounds or alkaline solvents to absorb CO2. Taking sodium hydroxide as an example, it reacts with CO2 to form stable sodium carbonate, which is then heated to obtain a pure CO2 stream.
It is estimated that capturing 330 million metric tons of CO2 from the atmosphere would require 300 cubic kilometers of water per year, posing new challenges amid growing global water shortages.
Currently, there are many other exploration directions for DAC technology, such as electroshock adsorption and membrane separation technology. These technologies all provide DAC with the potential to continuously innovate and improve efficiency. Especially recently, Ireland's Carbon Collect Limited has developed a device called the MechanicalTree™ that uses wind energy to passively capture CO2, significantly reducing energy costs.
In terms of applications, the potential for DACs is vast, ranging from enhanced oil and gas extraction, production of synthetic fuels, and even crop growth in agriculture. These different application needs have different requirements for the concentration of CO2 captured, and the need to capture relative to CO2 in air with a purity lower than 0.04% undoubtedly increases the difficulty and cost of production.
However, in the face of the increasingly serious climate crisis, whether DAC can become a key technology to change the status quo will depend on whether we can break through data limitations and enhance the sustainability of this technology?
With the global emphasis on reducing carbon emissions, the development prospects of DAC technology in the next few years are still worth looking forward to. By 2024, 53 DAC plants are expected to be operational globally, and by 2030 this number will reach 93.
The development of DAC requires corresponding financial and policy support, especially in the United States, where the government has pledged to invest billions of dollars in DAC projects to promote the commercial application of the technology. Such investments will not only support technological advancement but also help create new jobs. As the number of DAC facilities continues to increase, both carbon capture and carbon sequestration are important options for future climate challenges.
Every technology has its limitations. Can DAC achieve a breakthrough in technology and cost to make our atmosphere cleaner?
