Can removing carbon dioxide save the world?

  • The process of ‘negative emissions’ substract CO2 from the atmosphere, and is a way to limit the rise in the global temperatures.
  • Direct air capture is a technology which can removes CO2 directly from ambient air.
  • CSS or carbon capture and storage sequesters CO2 from emission source before the gas is able to enter the atmosphere.
  • CO2 removal is essential to avoid catastrophic climate change.
  • There are challenges in the use of CO2 removal technologies at the scale required.

The process of “negative emissions” substracts CO2 from the atmosphere, and is a way to limit the rise of global temperatures.

“Negative emissions” refers to the technologies that can limit rising global temperatures by removing CO2 from our atmosphere. The idea come from German physicist Klaus Lackner, who founded and now runs the Center for Negative Carbon Emissions at Arizona State University.

Direct air capture is the technology that removes CO2 directly from the air

The direct air capture technology captures CO2 from the air and turned it into calcium carbonate. As this technology targets CO2 in ambient air, it certainly can be used anywhere, especially high air pollution city centers.

Yet because of the CO2 content in the ambient air is too diluted making the technology relatively inefficient. Currently, there’s 6 companies using direct air capture technology, including Carbon Engineering in British Columbia, Global Thermostat in New York and Climeworks in Zurich. Carbon engineering removes around 1 ton of CO2 per day.

“Carbon dioxide removal is potentially a trillion-dollar enterprise because it offers a way not just to slow the rise o CO2 but to reverse it.”

Carbon captre and storage (CSS) sequesters CO2 from emission sources before it has a chance to reach the atmosphere

CSS takes CO2 from emission point and pumps it underground for storage in specific rock types. The Decatur project in Illinois has stored a million tons of CO2 since 2003 using CSS. The CO2 stored is rigorously monitored and has stayed put this far.

“In order to achieve the goals of the Paris Agreement, it (the UN Environment Programme’s annual Emissions Gap Report) notes, ‘carbon dioxide removal is likely a necessary step.”

A variation of CSS which is called bio-energy with capture capture and storage (BECCS) has the added benefit of energy production. Plants take in CO2, removing it from the atmosphere. As the plants are burned for energy, the CO2 released is sequestered by CCS.

CO2 removal is essential to avoid catasrophic climate change

As the CO2 level increases, the global temperature rises as well. Climate scientist have proposed a warming of 3 degrees Celsius as “catastrophic,” and the 2015 Paris Agreement aims to keep it to “well below 2 Deg C”.

Given the amount of CO2 already in the atmosphere and its continued production, computer modelling shows that is nearly impossible to reach the aims of the Paris Agreement without negative emissions.

“But everyone I spoke with, including the most fervent advocates for carbon removal, stressed the huge challenges of the work, some of them technological, other political and economic.”

There are challenges in the use of CO2 removal technologies at the scare required.

Effective CO2 removal must be done on a scale which requires huge investment in infrastructure and operations cost. In addition, producing the calcium used in direct air capture produces CO2, which for all intent and purposes, are counter-productive.

BECCS also requires a lot of arable land that could be used for food production. Still, some believe that, challenges aside, CO2 removal must be done.

Reference:

  • Can Carbon-dioxide removal save the World?, Elizabeth Kolbert, The New Yorker (2017)
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