It is important to know that it is difficult for gas to be stored in large quantities for a long time on the scale of 100 years through artificial facilities, so it must be sealed. The best way to do that is to return carbon dioxide to its original form, that is, to become a component of all kinds of living and non-living things. The very common way of living is to plant trees.
Although trees also exhale carbon dioxide, more carbon dioxide is formed during the growth of the plant, and part of the plant's roots, stems, leaves, flowers, fruits, and seeds is solidified there. But the question is where do we get so many places to plant trees, on the contrary, we are still cutting down forests for animal husbandry, farming, mining and real estate development.
So today, when we store the collected carbon dioxide on a large scale, we inject it into oil and gas fields. It's easy to understand that oil and gas are mixtures of gas and liquid, and they have been deposited in oil and gas fields for tens or millions of years. There has been no leakage for millions of years, so wouldn't storing carbon dioxide back also achieve the effect of no leakage?
In fact, it is really a natural gas storage place, which is not only tight and secure, but also has a large enough storage space. Especially in the global distribution, these pits are everywhere, ready-made, and there is no need for geologists to explore where to store gas, nor do they need to use large machinery to excavate. Carbon capture is just beginning, and those fields are enough for decades. Another ingenious aspect of this approach is that it is both the primary way to sequester carbon dioxide and the main way to capture and reuse it today.
This technology is called "CO2 flooding". Q: How did the oil get from the ground? A: Only in the Middle East, where oil is abundant, you can drill a deep hole and fill it with water, and the oil will gush out. In the oil fields of other regions, the oil is actually embedded in the crevices of the rock formations, and some method needs to be used to get it out.
This includes the use of hydrocarbons, chemical drives, thermal drives, and carbon dioxide drives to drive the oil out at high pressure. The effect of carbon dioxide driving is very good, because it can dissolve in oil, and after dissolving, it also makes the viscosity of oil drop significantly, expand in volume, and flow out more easily.
Since oil extraction requires a large amount of carbon dioxide to be injected into the oil fields, where does this carbon dioxide come from? Just use the captured one. So a lot of carbon dioxide helps people extract oil, and then it is sequestered, and the oil flows away in that big pit.
At present, there are 43 CO2 storage projects with a scale of 1 million to 9 million tons of storage capacity in the world. All of them are geological storages just mentioned, of which 18 have already been built, 5 are under construction, and 20 are under construction.
Those have been built, the longest of which is more than a decade old, and there hasn't been a single spill. However, the requirements for sealing are very harsh, and it is best to seal it permanently, and it is not possible to leak for thousands of years if it is not permanent, but it is difficult to verify it in this way, so we can only look at it while saving. Not to mention that there are many factors that can interfere with the storage effect, such as earthquakes, which cannot be prevented.
In addition, the second most important method of sequestration is to sequester carbon dioxide in the aquifers of the seabed. It doesn't have to be too deep or too far, just about 800 meters below the surface of the sea, which is the continental shelf. The continental shelf is constantly immersed in seawater, so the layers of the seabed a few hundred meters down contain a lot of water. If there is water, it can hold carbon dioxide, and carbon dioxide is pumped into the formation of the shallow seabed. Now, more than 20 million tons of carbon dioxide have been sequestered. Although this part cannot be reused, it has not been found to be leaking.
Carbon peaking and carbon neutrality are about each of us, and no one can stay out of it. On the bright side, if you're still hesitant about your career choice. Then why not join in this great cause that is destined to rewrite history?