Discussing Direct Air Capture

I previously had written about the future of preventing greenhouse gas emissions by the carbon capture process, focusing specifically on storing the captured carbon in a process known as carbon sequestration. However, in this blog I will be writing about a specific form of carbon capture, and the most popular one, known as direct air capture. As climate change is becoming the most pressing global issue, mankind is desperately searching for answers to prevent greenhouse gasses from escaping into the atmosphere, causing global warming. Direct air capture (DAC) is a unique solution which proposes removing existing carbon from the ambient air unlike other forms of carbon capture which tend to remove carbon directly from their source. 

 As always, let’s go into the numbers. Firstly, DAC is the most efficient carbon-removal process because it requires 30 to 100 times less land than other methods. DAC is necessary for the U.S. to achieve net-zero emissions by 2045. Around 560 to 1850 million tones of carbon is required to be captured and stored underground annually by DAC in order to reach this goal. The Swiss firm Climeworks’ largest plant currently removes 900 tons of co2 per year, sequestration equivalent to the work of 36,000 trees. 

So how exactly does DAC work? Well, there are various methods and technologies present in DAC. One common method uses chemical solvents to capture carbon from the atmosphere. When air passes over the chemical, they react, trapping the carbon and releasing the other elements in air. The captured CO2 can then be stored underground or in other areas with the carbon sequestration process (check out my blog on this).

The first benefit of DAC is that it can collaborate with renewable energy sources. Similar to my blog on vertical farming, DAC technologies can also be powered by renewable energy, such as wind energy, dramatically improving their environmental friendliness. This closes the carbon emission loop as powering DAC to remove carbon from the atmosphere would not subsequently release more carbon to do so. DAC helps to reduce the “emissions gap”. Although there are technologies being adopted to prevent carbon from being released into the atmosphere at its source, DAC helps to remove the already existing carbon in the atmosphere, stabilizing and reducing the current carbon levels in the atmosphere. 

DAC is also unlike other anti-carbon technologies in the sense that it is extremely scalable. Most of the time sustainable solutions take up tons of space. For example, the largest solar farm in the United States, Houston’s future Sunnyside farm covers roughly 250 acres. Nuclear power plants even might require the space of a whole city in order to remain out of harm from toxic radiation. DAC, on the other hand, is not subject to large-scale industrial installations; it can be employed in different settings of different sizes, allowing it to be used in various sectors. 

The biggest issue when it comes to implementing DAC technologies is that a massive amount of energy is required to power them. The energy required to run the DAC machines in 2100 at a 30% annual expansion rate is 300 exajoules per year. For reference, one exajoule is equivalent to around 173 million barrels of crude oil. Although renewable energy is an option, powering the DAC machines by 2100 would require a third of the annual renewable energy production as of 2021. It’s estimated that the amount of liquid or solid sorbent DAC requires to meet the atmospheric carbon reduction goals may reach between 46% and 191% of the total global energy supply. One possible solution to fuel the DAC machines is fusion power, but scientists are still unsure if Earth can support a fusion reactor. 

Of course, another challenge with DAC implementation is the cost. As of 2021, DAC is estimated to be 250 to 600 dollars per ton of co2, but is predicted to drop below 60 dollars by 2040. The reason DAC is very expensive is because co2 is not heavily concentrated in the atmosphere. There are also very few markets currently willing to purchase co2 so cost recovery is a problem. 

Additionally, carbon sequestration, the process for carbon storage after it is captured by DAC, has environmental risks. When the captured carbon is being injected into the ground or other geological formations, there is risk of triggering seismic activity or polluting groundwater. 

Although there are potential downsides to DAC, I believe that it is an absolutely necessary measure to achieve carbon reduction goals for the future. Implementing DAC on a large scale is the best solution such that we can prioritize developing infrastructure to make it more feasible. DAC is ideal because we will be able to combine it with prevention methods to attempt to reverse our harms to the atmosphere. Direct air capture and other forms of carbon capture are the future of solving global warming. 

Works Cited 

“Direct Air Capture: An Innovative Solution for Tackling Climate Change.” The Uptide, 16 June 2023, http://www.theuptide.com/direct-air-capture/. Accessed 22 June 2023.

Soshoot. “Direct Air Capture – Everything You Need to Know.” SolarShoot, 29 June 2022, solarshoot.com/direct-air-capture/.

Sutherland, Brandon R. “Pricing CO2 Direct Air Capture.” Joule, vol. 3, no. 7, July 2019, pp. 1571–1573, https://doi.org/10.1016/j.joule.2019.06.025.

Yoshida, Hiyori. “Direct Air Capture: Costs, Benefits, and the Future.” Risk Management and Decision Processes Center, 6 Aug. 2021, riskcenter.wharton.upenn.edu/lab-notes/directaircapture/.