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China has long overtaken the US as the world’s single largest emitter of fossil carbon dioxide (CO2) and other greenhouse gases: it discharged some 10.877 billion tons of CO2 into the atmosphere in 2017 according to data compiled by the European Union.
The majority of CO2 emissions in China come from either coal-fired power plants or coal-to-chemical processes such as the production of synthetic ammonia, methanol, fertilizers and natural gases.
Three Chinese cities – Guangzhou, Hong Kong and Shanghai are among the world’s top 10 on the Global Gridded Model of Carbon Footprints ranking.
Now the nation aims to capture some of the CO2 it produces to reduce its carbon footprint, with a carbon sequestration pilot facility up and running in Inner Mongolia, Xinhua reports.
China says that since coal is still a primary energy source taking up more than half of the nation’s energy mix, the country has worked hard to develop relevant technologies for its offset. These range from carbon capture, purification, pressurization, drilling to storage in saline aquifers more than a thousand meters deep in Earth’s crust.
CO2 can be captured out of air or fossil fuel power plant flue gas using an adsorption process or membrane gas separation technologies.
Built in saline aquifers beneath the city of Ordos, the facility is expected to capture no less than 100,000 tons of greenhouse gas per year. The project is part of a coal-to-liquids initiative being launched by the state-owned CHN Energy Investment Corp in Inner Mongolia, still one of China’s most fossil fuel- and coal-dependent provincial economies.
Now the Ordos facility can capture up to 90% of the waste CO2 produced from the use of fossil fuels in local electricity generation, such as the city’s coal-fired power plants. CO2 produced by coal-firing will be liquefied through purification, cooling and pressurizing after it is captured.
Geological formations are currently considered the most promising sequestration sites. Liquid CO2 will be injected through wells into saline aquifers between 1,500 and 2,500 meters underground for storage. The main advantage of saline aquifers is their large potential storage volume and their common occurrence.
A subsidiary under the Sinopec umbrella is also constructing a capture and storage facility in Shandong province, where there is a fertilizer plant that produces large amounts of CO2. The CO2 is to be captured by cryogenic distillation and will be transported via pipeline to a nearby oil field for enhanced oil recovery. Upon completion it will capture and inject 400,000 tons of CO2 per year.
Though the long term storage of CO2 is a relatively new concept, three extra facilities are also operational or in the late stages of construction in China, and, at least eight more across the nation are in early planning and development, most of which will capture emissions from power plants.