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Environmental Science
How Carbon Capture Works
Pulling CO2 from air and flue gas
Related Worksheets
Carbon capture is a set of technologies that removes carbon dioxide, or CO2, from the air or from pollution sources before it adds more warming to the atmosphere. Direct air capture is one approach that pulls ordinary air through large fans and separates out the small amount of CO2 it contains. This matters because CO2 traps heat and is a major driver of climate change. Carbon capture can help lower emissions, but it is not a replacement for reducing fossil fuel use.
Key Facts
- CO2 concentration in air is about 420 parts per million, or 0.042%.
- Direct air capture uses fans to move air across chemical sorbents that bind CO2.
- Captured CO2 can be compressed using PV = nRT to understand how pressure, volume, and temperature are related.
- Mass captured per year = capture rate per day x 365.
- Cost per ton = total cost ÷ tons of CO2 captured.
- Long-term storage usually injects compressed CO2 into deep rock formations where it can be trapped in tiny pore spaces.
Vocabulary
- Direct Air Capture
- A technology that removes carbon dioxide directly from normal outdoor air using fans and chemical materials.
- Carbon Dioxide
- A gas made of one carbon atom and two oxygen atoms that traps heat in Earth’s atmosphere.
- Sorbent
- A material that captures another substance, such as CO2, by absorbing it or binding it to its surface.
- Geologic Storage
- The process of injecting captured CO2 deep underground into rock layers where it can remain trapped for long periods.
- Carbon Utilization
- The use of captured CO2 to make products such as fuels, concrete, chemicals, or plastics.
Common Mistakes to Avoid
- Thinking direct air capture removes all pollution, which is wrong because it mainly targets CO2 and does not clean up every harmful gas or particle.
- Ignoring the energy needed to run the fans and pumps, which is wrong because carbon capture only helps the climate if its energy source has low emissions.
- Confusing carbon storage with carbon use, which is wrong because stored CO2 is meant to stay underground while used CO2 may later return to the atmosphere depending on the product.
- Assuming small capture plants can solve climate change alone, which is wrong because global emissions are many billions of tons per year and require large-scale emission cuts plus many other solutions.
Practice Questions
- 1 A direct air capture plant removes 1,000 tons of CO2 per day. How many tons does it remove in one year?
- 2 If capturing CO2 costs $250 per ton, how much would it cost to capture 40,000 tons of CO2?
- 3 Explain why a direct air capture facility powered by coal-generated electricity might not reduce net CO2 very much, even if the plant captures CO2 from the air.