The absorption of CO2 by terrestrial ecosystem is a natural carbon fixation process. During the growth of land plants, it is necessary to use CO2 to synthesize organic matter, which can absorb CO2 in a certain concentration range, thus saving the cost of separation and purification. Therefore, carbon sequestration through forest regeneration and limiting deforestation is considered to be the most economical way. Protecting and optimizing terrestrial ecosystems is conducive to maintaining and expanding carbon sequestration. Fertilizing the ocean is also a way to use ecosystems to achieve carbon sequestration. The idea of this method is to put micro-nutrients (such as iron) and macro-nutrients (such as nitrogen and phosphorus) into the ocean, thus accelerating the process of marine biological pump and increasing the absorption and storage of atmospheric CO2 by the ocean. This is mainly to increase the output of phytoplankton by increasing photosynthesis, and then to amplify the transformation of CO2 into organic carbon by means of biological chain, and then to realize carbon fixation through the mechanisms of gravity sedimentation and mineralization of organic carbon. Large-scale marine fertilization can increase fishery production, thus bringing business opportunities, which has also attracted the attention of some commercial groups.
In addition, chemical and biological technologies can be used to recover and reuse carbon dioxide. For example, the prospect of using CO2 to produce magnesium carbonate or CO2 inclusion compound is promising. If CO2 discharged from the world in 1990 is made into magnesium carbonate, it can be contained in solid matter with the spatial scale of10km×150m, which is beneficial to storage or reuse. The same applies to CO2 inclusion compounds. In biotechnology, non-photosynthetic microbial processes are mainly used to convert CO2 into useful raw materials, such as methane and acetate. Like terrestrial ecosystems, this technology does not need to purify CO2, thus saving the cost of separating, capturing and compressing CO2 gas. Buried capacity
Judging from the main types of carbon dioxide storage capacity in the world, geological storage has greater potential to capture carbon dioxide than forests and land, while the latter needs the support of scarce resources. The Declaration of APEC Leaders on Climate Change, Energy Security and Clean Development, issued at the 2007 APEC Summit, emphasized the importance of sustainable forest management and land use, and set an intentional goal of increasing the area of various forests in the Asia-Pacific region by at least 20 million hectares by 2020. However, in order to keep the "red line" of 65.438+08 million mu of cultivated land during the Eleventh Five-Year Plan period, the State Council recently issued a notice on improving the policy of returning farmland to forests, suspending the plan of returning farmland to forests of 6.5438+06 million mu (Beijing News, September 2007, 654.38+065.438+0), which further aggravated the difficulty of expanding forest area. In order to achieve the goal promised by the Tokyo Protocol, some developed countries regard geological storage of carbon dioxide as one of the main means to reduce carbon dioxide emissions, and have carried out a series of investigations, experiments and pilot studies in this regard, and gained many successful experiences. Therefore, it is more important and urgent to advocate geological storage of carbon dioxide in China by drawing lessons from international experience.
Victoria, Australia just opened the world's first large-scale carbon capture and storage facility in April 2008.