Market update · Asia-Pacific
China Connects First 100 MW/1,000 MWh Compressed CO₂ Energy Storage Plant to Grid
China Huadian has achieved the initial grid connection of a 100 MW/1,000 MWh compressed carbon dioxide (CO₂) energy storage plant in Mulei County, Xinjiang. This facility marks a significant advancement in long-duration energy storage technology, supporting renewable energy integration and carbon emission reductions.
SolTraCo market update · · 3 min readProject Overview and Location
The 100 MW/1,000 MWh compressed CO₂ energy storage plant is located in Mulei County, Xinjiang, within the Gobi Desert of Changji Prefecture. It forms part of a larger renewable energy development that includes 600 MW of wind and 400 MW of solar capacity. The plant occupies approximately 565,000 square meters and features five gas storage enclosures, 141 liquid CO₂ storage units, and 97 thermal storage units.
The facility offers a nominal discharge duration of 10 hours and is expected to generate around 200 GWh annually once fully operational.
Technology and Operation
Unlike conventional compressed air energy storage, the Mulei system uses CO₂ as the working fluid in a closed thermodynamic cycle. During charging, surplus electricity compresses gaseous CO₂, with heat generated being recovered and stored. The compressed gas is then cooled and liquefied for storage in pressure vessels.
During discharge, the liquid CO₂ is evaporated, reheated using the stored thermal energy, and expanded through a turbine to generate electricity. The gas is then returned to storage for reuse. The CO₂ can be liquefied at moderate pressures, allowing more compact high-pressure storage and eliminating the need for underground caverns.
Performance and Development
The plant's CO₂ turbine has a design efficiency exceeding 92%, with the system designed for at least 30 years of operation, over 20,000 start-stop cycles, and a startup-to-full-load time under 20 minutes. However, system-level round-trip efficiency and levelized storage costs have not been independently verified or disclosed.
This project builds on earlier Chinese demonstrations of compressed CO₂ storage technology, including smaller verification systems completed in 2022 and 2023. Internationally, similar commercial-scale facilities exist, such as Italy’s 20 MW/200 MWh plant in Sardinia, indicating the technology's progression from pilot to utility scale.
Sources
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