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What is carbon capture?
I’ve been wondering what carbon capture is for a while. It seems impossible that we can take carbon from the Earth in the form of oil, gas, and coal, burn it to make electricity, steel, or use it for other industrial processes, then bury it back into the Earth, and that will help reduce global warming? Sounds a little sleight-of-hand to me.
I suppose, though, that the inherent simplicity of burying carbon to get rid of it is no less paradoxical than the complex process whereby plants use sunlight, water, and carbon dioxide to make oxygen. Both are mysterious, and yet both work.
The process. To put it simply, carbon dioxide emissions from power generation or industry activity is captured, transported, and then stored deep underground.
- Capture – CO2 is separated from other gases that come out of smokestacks at coal or gas power plants or factories and then compressed.
- Transport – Compressed CO2 is transported as a liquid via road, pipeline, or sea to a storage site.
- Storage – At the storage site, CO2 is injected into rock formations in old oil and gas reservoirs or other geological formations about 1km or more underground for permanent storage.
How common is it: Carbon capture was first used in 1972 but its use has increased substantially in the past few years. Carbon capture facilities can be found throughout the US, Europe, Asia Pacific, and the Middle East. In 2022, the CO2 capture capacity increased 44% from the previous year to reach about 224 million tons per year of capacity under development (1). Globally, roughly 2 billion tons of CO2 is being from the atmosphere each year (2).
How useful is it in reducing global warming. The short answer is, carbon capture is useful in reducing CO2. How useful it is depends on a few factors.
For example, carbon that comes direct from a factory or power plant in large quantities is collected more efficiently than CO2 that exists in the atmosphere. In other words, you would have to process a lot of air to get one ton of CO2, and therefore is it generally considered inefficient to spend energy to try to capture CO2 from the general atmosphere.
Some CO2 from carbon capture is re-used instead of being buried. It can be injected into old oil fields to try and extract more oil. Some argue that collecting CO2 to conduct a process that itself creates more CO2 is counterproductive.
It’s also important that the CO2 that is buried is not going to seep into groundwater or leak back into the air. That’s why it’s important to go deep and inject the CO2 into rock that is porous enough to hold it.
Some critics of carbon capture say that the process only reduces carbon emissions at industrial plants by about 10%. They argue that what is most important is reducing the amount of CO2 created in the process in the first place, rather than merely trying to capture the CO2 that was created (3).
Summary. Carbon capture is a tool that is increasingly being used to help reduce overall CO2 emissions. While energy is needed to capture, condense, transport, and store carbon, the carbon capture process is a good way for factories and plants that must emit some level of carbon to reduce their overall emissions. I therefore believe carbon capture will continue to be used as one of the methods to reduce overall climate change.
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