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An Introduction to Carbon Capture Technology

This piece has been individually written as an introduction to Carbon Capture Technology discussions. The posts in this blog were prepared by Isabella Corpora in her personal capacity. The information, views expressed, and contents of this blog are solely the author’s and do not reflect the position or policies of any organization she is affiliated with. To learn more about mitigating GHG emissions from the oil and gas industry, join the Global Webinar on “Available Technologies that Contribute to Climate Mitigation in Upstream Oil and Gas Production”, scheduled on 06 July. Register here.

The Carbon Problem and CCS

The world remains highly dependent on fossil-based energy. It is hard, change. It’s hard to move away from fossil fuels and enter into a new low carbon era. Will electric cars be able to achieve long-distance trips the same way as cars that run on gasoline? What happens to the jobs of people who depend on the oil and gas industry? Fossil fuels drive our economies; what are the risks in moving away from them?

Inversely, we can ask ourselves what happens when we don’t shift away from fossil energy. Climate change is undeniably starting to show its effects and yet we are still slow to transition away from oil. Many climate scientists would note that the best thing to do with oil at this point is to simply leave it in the ground.

Carbon dioxide is currently above 417ppm in Earth’s atmosphere. As part of the natural carbon cycle, part of this carbon is absorbed into ecosystems through trees, soils, plants, and the ocean. Yet, there is too much carbon currently in the atmosphere as a result of anthropogenic activities, and evidence shows a warming planet past its critical thresholds. We are already witnessing accelerated sea level rise and ocean acidification, increasing extreme climate-exacerbated events, and adverse impacts on biodiversity and ecosystems on which peoples' livelihoods depend. Transitioning away from fossil fuel dependency is therefore inevitable. While we undertake this energy transition through more ambitious climate and energy policies, we can also consider how new technology can help us.

So, what do we do? For starters, we need to begin stopping carbon emissions from oil and gas reservoirs and other at-point sources as quickly as possible, and this can be achieved through what is referred to as carbon capture technology.

Carbon capture technology encompasses a variety of technologies doing just that- capturing carbon dioxide from the air, specifically at point sources such as power plants. It is referred to both as “carbon capture and storage” and “carbon capture, utilization, and storage” depending on whether the carbon is only captured, or if it is recycled (“utilized”) into other products, such as synthetic fuels or plastics. Imagine the technology as this: towers that have a chemical component on them, such as a liquid solvent like sodium hydroxide or a sorbent that is solid and dry. These chemicals bind with carbon dioxide mixed in flue gas streams when exposed to power plant emissions. Once the carbon dioxide is bound to the solvent or sorbent, it would then have significant heat applied to it (100°-900° C depending on which is used), separating again the carbon dioxide from say the solvent to then be trapped and stored. It seems like a redundant process, but at this moment in time this is one of the best methods for capturing carbon dioxide, other than naturally occurring photosynthesis. That purified version of carbon dioxide can then be transported to more permanent storage locations or used for purposes like enhanced oil recovery.

A schematic of Toshiba carbon capture technology in Japan.

Advantages of CCS

Many oil-producing countries and companies including Shell and Exxon already use carbon capture technology as a means for longevity: they account for their emissions and get to sell their product in a multi-trillion-dollar market. A temporary solution is presented while they figure out how to enter an inevitably carbon-negative world. Carbon capture is helpful in this regard in at least two ways: first, emissions are actually being captured and accounted for. Second, this carbon can be put away into the ground for storage, reducing its impacts on the atmosphere. Though not the most permanent means of sequestering captured carbon, enhanced oil recovery presents a way for carbon dioxide to stay below Earth’s surface. You can imagine enhanced oil recovery like an almost-empty hand soap bottle: you’re trying to push the lever down to get the last bits of soap out of the bottom, but nothing is coming up the pump because there is not enough content or pressure. Oil companies do something similar to get the last amounts of oil out of reservoirs; they inject carbon dioxide as a gas into the wells which provides enough pressure for the rest of the oil to be sequestered, then a cap can be put on the reservoir, maintaining the CO2 gas below the ground. There have even been developments such as the Allam-Fetvedt Cycle power generator that is capable of capturing not only carbon dioxide but also nitrous oxides and sulfur oxides, which is helpful in decreasing overall greenhouse gases (Global Status of CCS Report 2020). We’ve seen similar technology to this before, such as with scrubbers that have been developed for point-sources to capture sulfur dioxide, a pollutant that once led to high amounts of acid rain. Scrubbers are widely used and accepted, perhaps providing a precedent for mass CCS incorporation.

CCS has also already been incorporated into international climate frameworks, such as in Article 6 of the Paris Agreement and in the IPCC 5th Assessment Report, noting that in the scenarios with limited carbon mitigation, the world would need to heavily rely upon CCS technology to mitigate the worst effects of climate change by mid-century (IPCC 2014). In light of this international policy, many countries also are willing to incorporate CCS into their climate policies, notably in their nationally determined contributions (NDCs). Countries including Bahrain, China, Egypt, Iran, Iraq, Norway, Saudi Arabia, South Africa, and the United Arab Emirates are some that have included CCS in their NDCs, and many including the United States, Canada, and Japan are also incorporating it. There are more than 65 CCS facilities globally and many of them can capture up to 40Mt CO2 per year, which is a healthy start since globally an average of 36Gt CO2 is produced per year (Global Status of CCS Report 2020). Keep in mind though, 40Mt represents 40 million tonnes of CO2, while 36Gt is 36 billion tonnes- quite a substantial emissions gap.

A global map of CCS implementations (Global CCS Institute 2020).

Disadvantages of CCS

There are some real disadvantages of CCS usage though, notably as it delays the shift towards cleaner energies. This can further be exacerbated by domestic policies, such as the 45Q tax credit in the United States that allows for CCS technology credits to be used instead of stricter shifts to renewable energy. Why shift away from fossil fuels if emissions, the issue at hand, are being mitigated? To put this into perspective:

"Globally, there is approximately 2,000 GW of operating coal-fired capacity, with over 500 GW of new capacity expected by 2030. Over 200 Gt of new capacity is already under construction. While some coal and gas plants will be retired early, the average age of the natural gas fleet is 19 years in Asia and coal plants only 12 years. They have decades of economic life left. Without CCS retrofit or early retirement, coal and gas-fired power stations – current and under construction – will continue emitting CO2 at rates that will consume 95 per cent of the IEA’s Sustainable Development Scenario (SDS) carbon budget by 2050,” (Global Status of CCS Report 2020, p.62).

Exxon has already invested $3 billion USD into carbon capture technology and projects to lower its emissions outputs. It seems that without further legal incentives to mitigate emissions, it has a reason to continue polluting. However, oil companies are becoming increasingly under pressure to cut their emissions. New court cases such as the Friends of the Earth case against Shell in the Netherlands (May 2021) present new legal precedents and opportunities for emissions accountability in the private sector.

Carbon that is captured from CCS is also vulnerable and not necessarily removed from the atmosphere forever. Carbon that is stored in depleted oil and gas reservoirs through enhanced oil recovery has the risk of escaping back into the atmosphere as caps may not always be secure. Additionally, for carbon capture, utilization, and storage technology, the utilization and recycling of carbon means it could be reprocessed into fuels or plastics, but eventually carbon is released from those products and makes its way back into the atmosphere. The more permanent method of durable storage is through mineralization, but this is an expensive process and less frequently used. If you are interested in reading more about this, you can find information on mineralization here.


There are many questions still being asked during this transitionary period. On the one hand it is helpful to have a means of reducing emissions, yet it is disconcerting to think that this technology may further delay the shift towards cleaner energy. Even if the world does not see a hasty transition from oil, at the very least from a pollution standpoint, it is extremely important that we begin mitigating emissions that contribute to climate change and global warming.

If you are interested in learning more about these topics, please watch out for my next blog on CCS usage by governments and industry.

11 June 2021.

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