In one of my previous blogs, I touched on the process of carbon capture and how it is going to see new investments flowing into it as the Biden administration has specifically mentioned it as one of their objectives with the proposed infrastructure plan. I feel that this is now an opportune time to do another one of my ELI5 pieces covering carbon capture technology and the roadblocks and limitations it currently faces. In general, the idea behind carbon capture is that in order to mitigate some of our carbon emission production, we capture and store the carbon before it enters our atmosphere. Additionally, an alternative route of carbon capture is capturing carbon from the atmosphere. In both instances, captured carbon is stored underground.
As we burn fossil fuels, we get waste products in the form of a mixture of gasses called a flue gas. This mixture consists of carbon dioxide, water, sulfur dioxide, and nitrogen oxide. This gas is captured and funneled through a solvent to capture the carbon in this gas mixture. This fluid is then heated to remove the carbon. Once removed, the carbon can be stored underground where it does not affect our atmosphere. Our second form of carbon capture is pre-combustion capture. This means that carbon is extracted from a fossil fuel before it is burned. These processes consist of heating the fossil fuel in a chamber with pure oxygen. This then creates carbon monoxide and hydrogen. The second step is to treat this mixture with steam, causing the formation of carbon dioxide and even more hydrogen. Finally, the carbon dioxide can be separated from the hydrogen with a liquid chemical that will bind with the carbon dioxide. Both of these methods can effectively reduce the amount of carbon produced by an energy plant by 80%-90%.
The industrial revolution began about 260 years ago and throughout that time we have been dumping excess carbon into the atmosphere. Something needs to be done about the carbon already in the atmosphere, not just preventing more carbon from being emitted. This is where atmospheric carbon capture comes into the conversation. This method is more expensive than the previous two as it is harder to extract carbon from the general atmosphere, due to low concentration of 0.04%. In short, the way that this process works is similar to an air conditioning unit with an air filter in it. Air is sucked into a structure and passes over a surface covered in potassium hydroxide which binds with CO2. Then the CO2 can be unbound and collected.
Another key driver in capturing CO2 from the atmosphere are healthy forests as trees and other plants will consume CO2 during photosynthesis and produce oxygen as “waste.” And the good news is that the US is on a path of reversing centuries of deforestation. Forests have been stable in the US since the early 1900s, and in fact our forests have grown by 2% between 2007 and 2017 in terms of acreage and by 5% in terms of density. However, similar to climate change, deforestation is not a domestic issue but an international one and recent studies have shown that developed nations such as the US have been essentially “importing” deforestation from poorer nations from which we consume raw resources. What’s more troubling is that this deforestation occurs in the rich biodiverse rainforest biomes who’s health is a vital piece to our ability to successfully capture sufficient carbon to halt and possibly reverse the effects of global warming.
If you enjoyed this blog and possibly learned something new, I strongly implore you to consider donating to the US Forest Service’s Plant a Tree Program.