What are some of the techniques to remove carbon dioxide from the atmosphere?

You call for a massive effort to remove excess carbon from the atmosphere. How do you do that?

Techniques to remove carbon dioxide from the atmosphere include Agroecology, Bio-char, Bio-Energy with Carbon Capture and Storage (BECCS), Air Capture, and Reforestation, among others. Many of these techniques are referred to as “Carbon Dioxide Removal” (CDR) technologies.

  • Agroecology is an agricultural system that breaks the agricultural dependence on fossil fuels by relying on principles such as crop rotation, cover crops, and using waste products for fertilizer. Agroecology, especially when utilizing biochar, can be carbon negative while also providing a food supply that is more resilient to droughts and severe weather.
  • Bio-char is agricultural charcoal that can be buried in soil. Bio-char is produced by heating trees or plants (biomass) in a low or no-oxygen kiln, in order to prevent the materials from combusting. Since trees and plants extract carbon dioxide from the atmosphere as they grow, bio-char contains carbon. Decaying dead trees and plants release their stored carbon back into the atmosphere. When bio-char is buried in soils, it can sequester the captured carbon securely in the ground for hundreds to thousands of years.
  • Bio-Energy with Carbon Capture and Storage also makes use of biomass. In BECCS systems, trees and plants are burned in power plants to produce electricity. The carbon dioxide exhaust is captured and stored in geological reservoirs underground. If used at all, these techniques should be done in moderation, as bio-char and BECCS could pose threats to arable land and food supplies, if used inappropriately or excessively.
  • Air capture technologies are industrial systems that suck carbon dioxide directly from the atmosphere using fans. The carbon is then stored deep underground in geological formations for thousands of years. Air capture tends to be expensive and energy-intensive.

  • Reforestation—planting trees on deforested land—can also remove carbon dioxide from the atmosphere, although reforestation projects could compete with other land uses, such as agriculture. An international effort to plant trees en masse for the rest of the 21st century could remove the amount of carbon dioxide released into the atmosphere through all historic deforestation.

 

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  • commented 2016-04-07 11:42:58 -0400
    Although all of the bio approaches are worth pursuing, I don’t see any plausible scenario for removing the 10 – 20 gigatons/year from the atmosphere and storing it “safely, forever”. At least not with bio & reforestation alone. If we are to have any chance of getting on and staying on the IPCC’s RPC2.5 trajectory, which is the only “safe” way forward, then we’ll quickly need what right now is science fiction – the direct removal from the atmosphere plus “forever, safe” storage, and “zero carbon” energy sources to power this approach. And if that “miracle” isn’t enough, we’ll need virtually all human transportation, heating & cooling, cooking, industrial energy to be “low to no” carbon within the next couple decades.