On October 2, China's first 100-megawatt-class compressed carbon dioxide energy storage project — the China Huadian Xinjiang Mulei Compressed Carbon Dioxide Energy Storage Project — was successfully connected to the grid, opening up a new green, zero-carbon, efficient, and economical pathway for large-capacity compressed carbon dioxide energy storage.
First 100-Megawatt-Class Compressed Carbon Dioxide Energy Storage Project Connected to the Grid
This is China's first 100-megawatt-class compressed carbon dioxide energy storage project. It stands like a giant "power bank" on the Gobi Desert, capable of flexible storage and discharge according to grid demand — charging during low-demand periods and discharging during peak periods, with minute-level response. Each year, it can store 290 million kWh of electricity during grid low-demand periods and release 180 million kWh of clean green electricity during peak periods, with continuous power generation for over 6 hours.
The project is equipped with 5 gas storage warehouses, 141 liquid storage units, and 97 thermal storage units. The entire system uses carbon dioxide as a closed-loop circulation medium, representing an energy storage technology based on gas-liquid interconversion and two-state synergy. It does not rely on geological conditions, has low pressure and temperature requirements, offers high reliability and low cost, and its key core technologies for design and manufacturing are fully independent and controllable.
Ma Guojiang, Project Manager of the China Huadian Mulei Compressed Carbon Dioxide Energy Storage Project: Compressed carbon dioxide has a higher energy density ratio and also possesses multiple advantages including high efficiency, low cost, high safety, and zero pollution. The project's design efficiency represents the highest power generation efficiency of any carbon dioxide generator unit in China. Upon completion, the project will generate approximately 200 million kWh annually, save 50,000 tons of standard coal per year, and reduce carbon dioxide emissions by approximately 170,000 tons.
The project will strengthen the grid's peak-shaving and valley-filling, frequency regulation, and voltage regulation capabilities, significantly improve the flexibility and safety of the power system, continuously expand green electricity supply, and is of great significance for ensuring energy security and promoting green development, helping to advance China's new-type power system economic development.
How Does Compressed Carbon Dioxide Energy Storage Generate Electricity?
As a new type of energy storage technology, how exactly does compressed carbon dioxide achieve power generation?
The compressed carbon dioxide energy storage and power generation system mainly consists of a gas storage system, a liquid storage system, a compression system, a heat storage system, a heat exchange system, and an expansion power generation system.
During the energy storage phase, during low-demand periods, surplus electricity is used to drive an electric motor to compress carbon dioxide at ambient temperature and pressure through a compressor. This process is like inflating a tire with a pump — the pump heats up, and compressing carbon dioxide likewise generates a large amount of heat. The project first stores this heat, then condenses the compressed carbon dioxide into liquid form for storage. This results in a higher energy density ratio, meaning more energy can be stored.
During the power generation phase, during peak-demand periods, the project uses an evaporator to gasify the liquid carbon dioxide, then uses the heat stored during the compressed carbon dioxide energy storage process to heat the high-pressure liquid carbon dioxide into a high-temperature, high-pressure gaseous state, which drives turbine blades to rotate, thereby generating clean green electricity.
Compressed carbon dioxide, as a new type of energy storage technology, is an important technological exploration for building a new-type power system, an important support for achieving carbon peak and carbon neutrality goals, and an important field for fostering new domestic energy business forms and seizing new international strategic high ground.