Climate change is humanity's most imminent catastrophe in our modern era. We know that one of the largest contributors toward accelerating climate change is the emission of carbon dioxide into the atmosphere. A simple question to ask might be “how do we remove this carbon dioxide?” - This is exactly what 16-year-old me asked in the summer of 2023. The question's premise is simple and direct, neither of which are verbs I’d use in describing its answer.
Direct Air Capture is a subset of Carbon Capture and Storage (CCS) - a term used to describe a range of processes that capture or sequester carbon dioxide, and then store it afterwards. This is an important distinction to make early on. A popular rebuttal that can be used against the pitch of investment into CCS tech is to say, “why invest in capturing this carbon dioxide when we could invest in not emitting it at all?” This certainly has merit for some applications of CCS - specifically post-combustion filtration. This is where carbon filtration equipment is fitted to a smokestack or similar - at the point of the carbon dioxide emission. Think filtering the fumes of a coal fueled powerplant. Of course there’s merit toward the idea that any investment should be redirected into scaling renewables, with the eventual aim of shutting down that coal powerplant entirely. This is exactly where the optics of CCS turns from one of merely a bad investment - doing less ‘good’ than alternative investment opportunity, to a sector of tech that is argued to be ‘part of the problem’ - doing more to extend the run of fossil fuel emitting energy production, than any climate benefit.
Where Direct Air Capture (DAC) fundamentally differs is that it is geared toward removing carbon dioxide directly from the ambient air. While renewables can be said to be the technology that saves us from our future emissions, Direct Air Capture can be said to be that which saves us from our historic emissions. As such, I personally would label a successful DAC sector as one that is critical toward our efforts in reducing the impact of climate change.
If we have common ground agreeing to DAC’s importance, a reasonable question to ask is “if it’s so important, why isn’t it everywhere like renewables increasingly seem to be?” This is a question whose answer strikes toward the core of DAC’s economical and technological issues along with what my project aimed to contribute toward addressing.
The challenges (economically successful) DAC faces mostly arise from the statistics of our atmosphere. Our air is made up of about 78% nitrogen, 21% oxygen, 0.9% argon, 0.04% carbon dioxide + trace amounts of various others (ammonia, carbon monoxide, helium, hydrogen, methane, etc.) [1]. Put simply, to filter for carbon dioxide, means that 99.6% of the filtration medium is waste. There are few industries in existence that survive on such low statistical strike rates.
The associated technological complexities of filtering are passed down the stream eventually represented by a high cost of capture. Here lies the crux of why DAC hasn’t yet scaled, it’s a combination of perceptions, regulations, but ultimately technical feasibility. This is not to say that none of these can be overcome, but if your goal is to contribute to DAC’s commercial viability, it is vital to approach that goal with these challenges in mind.
Thank you for reading!