We’ve heard the dire warnings for years. As greenhouse gases—particularly Carbon Dioxide (CO2) and Methane—build up in the atmosphere, heat will get trapped and reflected back toward the planet. The hotter the planet gets, the more easily greenhouse gases generate, get trapped and reflect heat back. It’s a cascading feedback effect.
According to a report from the National Oceanic and Atmospheric Administration (NOAA ), CO2 in the atmosphere before the industrial revolution (1870) was relatively steady at 280 ppm, a level that was consistent for nearly 6,000 years.
[PPM, or parts per million, is a measurement used to describe the density of a substance as a ratio. For every million molecules, 280 of the molecules are CO2.]
However, there have been two significant inflection points in the history of CO2 in the atmosphere. The first was during the industrial revolution when the rise of industry was powered by large-scale burning of fossil fuels (the primary generator of CO2). During this time, the release of CO2 emissions was estimated to be at 66 million tons per year. The second inflection point – possibly induced by the industrialization of World War 2 – was in the 1940s, a period in which the release of CO2 had increased to 5 billion tons per year.
Since then, the production of emissions has only accelerated. By 2020, the release of CO2 emissions had climbed to 35 billion tons per year.
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So, with the planet’s rapidly growing greenhouse gas pool and the devastating impacts it’s having on everything from climate to policy to business, what’s being done in response? One of the many answers to this question lies in a quickly evolving technology that captures the carbon.
What is carbon capture technology?
Carbon capture technology (CCT) is a broad set of technologies and processes designed to capture carbon dioxide emissions before they enter the atmosphere. Simply trapping the carbon dioxide is a good step. But what happens next?
The captured carbon is compressed and can be used in a variety of ways—from bioplastics to transformation into industrial fuels—or transported to long-term storage. For these reasons, it is also variously known as CCUS (carbon capture, utilization, and storage) and CCS (carbon capture and storage).
The concept of capturing and storing carbon as a way of preventing it from getting into the atmosphere goes back to 1977. The technology itself actually goes farther back, however its purpose was industrial. A process that has become known as Enhanced Oil Recovery, or EOR, uses CO2 injected into oil fields to make it easier to remove the oil.
Carbon capture technology is a vital tool in the arsenal to fight climate change because CO2 in the atmosphere takes an extraordinarily long time to dissipate naturally. Unlike other greenhouse gases such as Methane—which can decompose in as little as 12 years (but is significantly more potent) according to the International Energy Agency—Carbon Dioxide can remain in the atmosphere between 300 and 1000 years.
Even by the more conservative estimate, this means that virtually every bit of CO2 that has entered the atmosphere since the Industrial Revolution began remains. By capturing the carbon at the point of emission, carbon capture technology stands to help stem the rate of build-up in the atmosphere.
How does carbon capture technology work?
There are three primary technologies available to capture CO2:
- Post-Combustion Carbon Capture
- Pre-Combustion Carbon Capture
- Oxy-Fuel Combustion Systems
As the name implies, post-combustion carbon capture extracts carbon dioxide from the exhaust in the manufacturing process. This is the primary method used in existing power plants and factories. Physical or chemical absorption removes the CO2 from emissions and then it can be stored. One of the benefits of this process is that it is the least costly to retrofit existing infrastructure.
Similarly, pre-combustion carbon capture works by separating the CO2 from the fuel before the manufacturing process. In this process, a chemical solvent absorbs CO2 which has been drawn out of gasified natural gas or coal. While ultimately it is thought that this technology will be more efficient than post-combustion carbon capture, it is costly to retrofit existing facilities.
The oxy-fuel combustion system takes a different tack altogether. Fuels are burnt in an oxygen-rich environment. In this method, the oxygen burns off, higher temperatures abound and the resulting exhaust is primarily CO2 that is already separated, eliminating the need for extraction.
The key metric to consider with all three technologies is efficiency and each of these technologies provides a see-saw of benefits.
For example, oxy-fuel combustion may render exhaust that requires no separation but retrofitting existing factories and plants is financially and practically impossible. It is easier to retrofit an existing plant with a post-combustion capture system, but the result does not provide the same level of removal as an oxy-fuel technology would.
In general, pre-combustion is more efficient than post-combustion, but the costs of the installation and development of supporting technologies (such as hydrogen turbines) are high.
After utilizing one of the three main methods to capture CO2, what happens next? The gas is readied for transportation—a process that involves compressing and cooling CO2 into a liquid state so that it can be more easily moved via pipelines and/or traditional shipping methods.
Following this step, comes the actual storage. Upon arrival to the storage site, the CO2 fluid is injected into geological formations that sit deep underground—spaces that are typically former oil and gas reservoirs, coal beds or saline formations. There, deep beneath Earth’s surface, the CO2 can be stored long term without risk of it being released into the atmosphere.
Why is carbon capture technology important?
A 2021 report from the Global CCS Institute claims that the current and planned manufacturing plants will be capable of capturing 40 million tons of CO2 annually. While this is a very small fraction (~0.1% relative to 2020 emissions) of the amount of CO2 produced, it also represents just 31 facilities worldwide, 10 of which are in the United States.
Reports vary on the scope of new construction but several sources point to between 100 and 200 new facilities being online by 2030, with a capacity to process between 150 and 220 million tons of CO2.
One organization that is bullish about carbon-capture is the International Energy Agency. Their Sustainable Development Scenario, a plan that describes a major energy transformation through new technologies that spur innovation, sees carbon capture as having the possibility of generating low-carbon electricity. They estimate that by 2040, 5% of global power will be generated through carbon capture-equipped power plants. However, to meet a net zero scenario by 2030, simply completing the current projects under development will not be enough. A significant level of additional carbon capture and storage capacity (~1300 Mt CO2/year) is required.
Nevertheless, even the most ambitious perspectives on carbon capture admit that meaningful change will be difficult to accomplish without investing in other areas of carbon reduction.
Capacity of Large-Scale CO2 Capture Projects, Current and Planned vs. the Net Zero Scenario, 2020-2030
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What does the future of carbon capture technology look like?
One thing that is clear is that carbon capture technology is not going to solve the problem of CO2 in the atmosphere on its own. Still, it’s a promising and necessary approach that is a viable part of a multi-pronged solution to managing the impact of human activity on the environment.
But before anything substantial can be achieved in the space of carbon capture technology, there are certain barriers that need to be addressed to lay the groundwork for widespread growth in this sector.
- Cost: Whether retrofitting existing facilities or building new ones, CCT is costly to implement—especially in relation to the energy and equipment needed during capture and compression phases. What’s more is, as with most early-stage technology, financial returns are less certain than tried and true operations, resulting in higher risk premiums to attract investors. Advancing scalable technologies will play a role in reducing the up-front expense associated with carbon capture.
- Accessibility: While tackling industrial output of carbon dioxide is a good place to start, transportation – moving people and goods around the world – accounts for 22% of annual CO2 emissions. There needs to emerge a practical product that can capture emissions from a vast amount of small sources—something that can be accessible across the board from global enterprises to ordinary individuals. One such solution is being explored by chemists at the University of California, Berkeley and other institutions who believe they can design a product for capturing CO2 from automobile exhaust.
- Safety: CO2, especially when taken from a variety of sources, can have variability to its purity. Those deviations, combined with the cold temperatures of the matter can sometimes cause damage to the pipelines and vessels that help transport it, ultimately leading to leaks and possible explosions as the compressed fluid rapidly heats and expands back into a gaseous state. This danger extends into the storage sites as well.
Despite the barriers that impede the deployment of carbon capture technology, what will ultimately encourage its widespread adoption is the growing severity of climate change, and the public’s support of CCT as one of its contributing solutions. Public support, however, will not happen overnight.
CCT education and advocacy needs to be a steady, collective effort. Companies must lead, doing what they can to incrementally develop and employ more efficient and feasible CCT and demonstrate its benefits in conjunction with other sustainable technologies to their stakeholders. Governments must step in too and offer greater incentives to those who spur the creation and utilization of such systems. Lastly, individual demand will drive its adoption home, through the power of both discourse and dollar.
