What Is Carbon Capture and Storage?

Feb 19th, 2012 | By | Category: Sustainability

Stabilization of atmospheric carbon dioxide (CO2) levels has become widely accepted as necessary in order to limit the long-term warming of global temperatures by 2 to 3°C and thus avoid devastating environmental consequences. Because the use of fossil fuels is expected to continue to increase in the future, new, innovative strategies need to be placed alongside the already well established ones, such as the use of renewable resources and achievement of better energy efficiency. One such strategy, which has emerged only over the past decade or so, is the idea of capturing the CO2 from large emitters (such as factories and power plants), transporting it to an appropriate site, and storing it underground for thousands of years. This strategy, or technology, is referred to as carbon capture and storage (CCS).

Many of the practices and technological components of CCS have been in commercial operation for the past several decades, particularly in the oil industry, which has been injecting CO2 into oil formations to recover additional oil since the 1970s.

 

Carbon Capture Technologies

There are essentially three types of capture technologies that show the most promise and will be commercially viable in the near future:

  • Post-combustion: the CO2 is separated from the flue gas by a chemical solution after the primary fuel has been combusted;
  • Pre-combustion: the primary fuel is transformed to produce hydrogen, and the CO2  is removed before combustion; and
  • Oxy-fuel combustion: the fuel is burned in an oxygen environment, resulting in a CO2-rich waste gas stream. Once the CO2 has been captured, it is then compressed, which liquefies it and makes it ready for transport to an appropriate storage site.

 

CO2 Transportation

Transportation of CO2 will occur primarily through pipelines; ships and rail might also come to play a role later, as storage sites are located further from the capture plant. While extensive networks of pipelines that would transport CO2 already exist, new pipeline infrastructure will be needed once CCS becomes deployed on a large scale.

 

Carbon Storage

Possible CO2 storage locations on land include depleted oil and gas reservoirs, un-minable coal seams, and deep saline aquifers; an alternative to land storage is to transport the CO2 out into the ocean and inject it deep into the ground. The saline aquifers are thought to hold the largest potential capacity for storage. Here, the CO2 is essentially injected deep underground into the sandstone layers, where it is contained by the natural pressure of the impermeable nonporous cap rock layers above. 

An overview of CSS techniques is depicted in Figure 1.

Figure 1: Main Stages of the CCS Process. Source: SCCS, 2011.

 

Conclusion

Increasingly, CCS is being seen not as a silver bullet, but as one of the key components in the portfolio of mitigation strategies and measures. It can play a major part in our transition towards a low-carbon economy, and it can become a low-emission option for many emerging and developing economies, whose use of fossil fuels is predicted to increase significantly over the next decades. While demonstration projects are underway, a number of scientific, economic, social, and legal problems remain, preventing CCS from living up to its potential.

 

About the Author

Marko Maver is a doctoral student in international environmental law at the University of Sheffield in the United Kingdom. Mr. Maver’s research focuses on the legal aspects of carbon sequestration. His Master of Arts dissertation, Carbon Capture and Storage: An Analysis of the Barriers to the Development and Deployment, describes the economic, social, and political barriers to the development and deployment of CCS technologies.

 

Photograph: Sunflower 2 by Zsuzsanna Kilian, Budapest, Hungary.

 

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4 Comments to “What Is Carbon Capture and Storage?”

  1. pdoortman says:

    Returning CO2 into organic materials is indeed a highly desirable option. The most practical way is indeed by fertilizing plants with it. This is indeed done in the Netherlands. CO2 from Rotterdam refineries is fed to massive greenhouses in nearby Westland.
    The biggest technologal challenge in CSS is the Capture step. With industrial emissions it can be done at a cost. But with mobile emissions (cars!) it is far too costly and impractical.

  2. Alain Renard says:

    As an organic chemist, I think there should be projects to transform CO2 back into organic materials with catalysis (what photosynthesis does!)… But the overall process should be looked at with thermodynamics aspect!

    Alain

  3. Miha says:

    nothing has a value unless it can be used for/in something..apart from enhanced oil recovery, for which it is already being used, what else could the captured CO2 be used for? don’t think it holds any intrinsic value to anyone..and besides, the MAIN point of CCS is the last part…storage/sequestration.

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