Potential mapped for offshore carbon stores

China has huge potential to tap for geologic carbon sequestration — storing carbon underground in geological formations — in its offshore waters to mitigate carbon emissions, thanks to the favorable geologic structures in its vast territorial sea, according to a recent survey.

With stable crust, vast sedimentary basins and many thick stratigraphic traps, offshore China has the potential to store up to 2.58 trillion metric tons of carbon dioxide, according to the China Geological Survey, an affiliate of the Ministry of Natural Resources.

As an important measure to mitigate carbon emissions, geologic carbon sequestration is a technology that injects captured greenhouse gases into underground geologic formations to isolate them from the atmosphere. Currently, carbon storage projects are mainly carried out onshore in China.

If the offshore potential is fully tapped, it may make significant contributions to the country's climate targets of peaking carbon dioxide emissions before 2030 and realizing carbon neutrality before 2060.

Carbon neutrality can be achieved by balancing emissions by their removal or by eliminating anthropogenic emissions.

According to the Ministry of Ecology and Environment, excluding emissions from land use, land-use change and forestry, China's total greenhouse gas emissions in 2012 were equivalent to roughly 11.9 billion tons of carbon dioxide.

The survey is the first ever to assess the potential and suitability of the country's major sedimentary basins for geologic carbon sequestration, the China Geological Survey said in a media release in early January.

"The survey has essentially figured out the resources that can be used for carbon sequestration in China's territorial waters," it said. "It also specified the basins and belts that are suitable for the technology's application."

The country's central authorities have listed carbon capture, use and storage (CCUS) as an important technological means for the country's climate targets.

In October 2021, the Central Committee of the Communist Party of China and the State Council, the country's Cabinet, jointly unveiled an overarching guideline for the country's climate targets. CCUS is included in the document as one of the technologies the country plans to accelerate research, development and promotion.

The Action Plan for Carbon Dioxide Peaking Before 2030, which was made public by the State Council shortly after the guideline, vowed to promote large-scale CCUS demonstration projects.

In August that year, the country's first offshore CCUS demonstration project was put into operation by China National Offshore Oil Corporation.

The project will permanently store 1.46 million tons of carbon dioxide in the Pearl River Mouth Basin reservoir. This is equivalent to planting nearly 14 million trees, according to the company.