Carbon sequestration refers to measures to increase the carbon content of carbon pools except the atmosphere. Include physical carbon fixation and biological carbon fixation. Physical carbon sequestration is the long-term storage of carbon dioxide in exploited oil and gas wells, coal seams and deep seas. Biological carbon fixation is to convert inorganic carbon, that is, carbon dioxide in the atmosphere, into organic carbon, that is, carbohydrates, which are fixed in plants or soil.
There are two common ways to fix carbon: photosynthesis, such as various green plants and photosynthetic autotrophic microorganisms (such as cyanobacteria); Chemical energy synthesis, such as nitrifying bacteria using ammonia oxide to synthesize organic matter. Biological carbon fixation improves the carbon absorption and storage capacity of the ecosystem and reduces the concentration of carbon dioxide in the atmosphere.
On June 2nd, 2022, the first first-class highway running through Taklimakan Desert in China, the "Zero Carbon Demonstration Project" of Tarim Desert Highway, was officially put into operation. Since then, this road running through the largest desert in China has become a zero-carbon expressway. After put into operation, the shelterbelts on both sides of expressway can sequester 20,000 tons of carbon every year, completely neutralizing the carbon emissions of vehicles in the past.
Marine physical carbon sequestration refers to the diffusion and transfer of carbon dioxide-carbonate system in seawater to the deep sea through the action of marine "physical pump", and finally forms calcium carbonate, which is deposited on the seabed to form calcareous ooze, thus playing a role in carbon sequestration. This gas exchange process at the air-sea interface and the hydrodynamic process of transporting carbon dioxide from the ocean surface to the deep sea are called "physical pumps".
Deep-sea sealing carbon fixation
Carbon sequestration in deep sea is another effective carbon sequestration method. As fossil fuels, especially coal, are still the most important energy fuel in China, one of the solutions is to find a place and method to store a large amount of carbon dioxide for a long time, so as to fulfill China's commitment to reduce carbon dioxide emissions and deal with possible "carbon tariffs" in international trade.
Scientific research has found that in the deep sea, carbon dioxide will form hydrate with water and form a solid shell outside, which limits the contact between carbon dioxide and seawater; When the depth of seawater exceeds 3000m, liquid carbon dioxide can form a stable hydrate shell, and the gas stored in this way will be enough to cope with the most serious earthquake or other earth upheaval.