EME 444
Global Energy Enterprise

Carbon Capture and Storage (CCS)


There are two general approaches to addressing anthropogenic climate change: mitigation and adaptation.  Adaptation refers to adjusting to the impacts of climate change that occur or are projected to occur, while mitigation refers to preventing greenhouse gas emissions from impacting the climate in the first place.  (Keep in mind that planning - of both the market and nonmarket variety - can address both simultaneously.)

There are two general ways to mitigate emissions. Prevention is most often the focus of mitigation efforts. The most common examples are using renewable and carbon-free energy sources, and energy efficiency. However, Carbon Dioxide Removal (CDR) technologies and methods can also be effective mitigating agents.  CDR technologies are frequently mentioned by many governments and organizations, including by the Intergovernmental Panel on Climate Change (IPCC) in their Assessment Reports, including in their most recent report, the Sixth Assessment Report (AR6). (The Physical Science Basis section of AR6 was published in August 2021, with the full report released in the spring of 2022. This section may have been subject to some revision.) The IPCC also noted the possible need for CDR in their oft-cited Special Report that was published in 2018.  The IPCC is the most prominent and well-regarded international organization studying and proposing solutions to climate change. Carbon capture and storage (sometimes referred to as carbon capture and sequestration), or CCS, is a prominent CDR technology. The IPCC states the following in the Executive Summary of Chapter 2 of their 2018 report.

All analysed pathways limiting warming to 1.5°C with no or limited overshoot use CDR to some extent to neutralize emissions from sources for which no mitigation measures have been identified and, in most cases, also to achieve net negative emissions to return global warming to 1.5°C following a peak (high confidence). The longer the delay in reducing CO2 emissions towards zero, the larger the likelihood of exceeding 1.5°C, and the heavier the implied reliance on net negative emissions after mid-century to return warming to 1.5°C (high confidence). The faster reduction of net CO2 emissions in 1.5°C compared to 2°C pathways is predominantly achieved by measures that result in less CO2 being produced and emitted, and only to a smaller degree through additional CDR. Limitations on the speed, scale and societal acceptability of CDR deployment also limit the conceivable extent of temperature overshoot. Limits to our understanding of how the carbon cycle responds to net negative emissions increase the uncertainty about the effectiveness of CDR to decline temperatures after a peak. {2.2, 2.3, 2.6, 4.3.7}.
CDR deployed at scale is unproven, and reliance on such technology is a major risk in the ability to limit warming to 1.5°C. CDR is needed less in pathways with particularly strong emphasis on energy efficiency and low demand. The scale and type of CDR deployment varies widely across 1.5°C pathways, with different consequences for achieving sustainable development objectives (high confidence). Some pathways rely more on bioenergy with carbon capture and storage (BECCS), while others rely more on afforestation, which are the two CDR methods most often included in integrated pathways. Trade-offs with other sustainability objectives occur predominantly through increased land, energy, water and investment demand. Bioenergy use is substantial in 1.5°C pathways with or without BECCS due to its multiple roles in decarbonizing energy use. {2.3.1, 2.5.3, 2.6.3, 4.3.7}

It is a widely shared belief that unless policies are enacted to aggressively reduce CO2 emissions that carbon capture technologies will be necessary to avoid the worst impacts of climate change. The video below from the British Geological Society provides a good introduction to this process. Please watch the following (4:45) video.

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What is carbon capture and storage (CCS)?
Click for a transcript of "What is carbon capture and storage (CCS)?" video.

MIKE STEPHENSON: Carbon capture and storage, or CCS, is an important new geoengineering solution to climate change. The idea is simple-- we capture CO2 from large point sources, like power stations, cement factories, and oil refineries, and store it, or dispose of it deep underground. This stops the CO2 from getting into the atmosphere.

But we want to know that CCS works, and most of all that it's safe. CCS could be an industry the size of present-day North Sea oil within a few decades. It's simply the reverse of the oil and gas business, putting climate-changing CO2 gas back in the ground after fossil fuels have been burned. This new technology is one of the ways that Britain could reduce its emissions, as well as other big CO2 producers, reduce theirs.

Point sources would be connected in clusters to pipelines that would take CO2 across the country and onshore to wells, where it can be injected into former oil or gas fields, or deep aquifers. The argument is that if the underground storage structure is good enough, the gas will stay there for millions of years, just as natural gas does. Scientists have already shown, at a small scale, that they can capture, transport, and store CO2.

In Britain, we're lucky in being close to one of the largest areas of potential storage for CO2 in Europe. The rocks under the North Sea could absorb about 22 billion tons of CO2, which is 180 years of the UK's 20 largest point sources. This is a really hefty reduction in Britain's emissions.

We're very confident the CO2 won't leak. One of the reasons why is that we know a lot about natural gas, or methane, in the North Sea. We've been extracting natural gas from the North Sea for many years in this country. And as geologists, we know that that methane or natural gas has been in those structures for literally millions of years. It's actually stayed put for millions of years.

So if we engineer the structures in which we hope to store our carbon dioxide to the same level, there's no reason why they should leak at all. The CO2 should stay down there for millions of years. We're also very confident from the science because, for example, we've been injecting CO2 for a long time.

There are various places in the world where CO2 is successfully injected into rocks. For example, in the United States, CO2 is injected for enhanced oil recovery in oilfields, where it flushes the oil, the last remaining oil out of fields. And also, in the Sleipner field in the North Sea, we've been injecting CO2 for well over 10 years, very successfully.

Finally, we feel that we can image, or we can actually see the CO2 collecting in reservoirs. Using very sophisticated seismic techniques, we can actually see the layers of CO2 as they collect. So overall, science gives us a lot of confidence that our containers, the structures where we hope to store CO2 will not leak.

The UK is taking a lead in CCS worldwide, both in terms of British government support for CCS, but also because British scientists are exporting knowledge and expertise to big emitters in the developing world, like China and India.

Large-scale CCS can't happen until we know that it's viable, and that the CO2 won't escape. Would money spent on CCS be better spent on renewable energy, like wind farms? Is CCS a big opportunity for the UK? These are reasonable questions to ask. To answer them, scientists are working around the world to find out whether CCS is a viable long-term option.

There are many good sources of information about CCS, including The Global Status of CCS: 2021, research by the World Resources Institute, also from the Energy Information Administration, and the International Energy Agency. The best source of current and balanced information on this topic, at an appropriate level of depth and detail are from the source below, which has links to referenced studies.

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For an updated (but CCS industry-based) perspective, feel free to page through the Global CCS Institute's The Global Status of CCS: 2019, which is the most recent report as of September 2020.

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