Under the vast grasslands of Xiwuzhumuqin Banner in Xilingol League, Inner Mongolia, a giant gas storage facility is brewing - it is not used to store natural gas or oil, but to store compressed air. When there is an excess of new energy generation, electricity is used to compress air and inject it into underground "warehouses"; When the power grid needs it, the high-pressure air released drives the expander to generate electricity.

In 2026, this concept will officially move towards implementation. The pre bidding results for the EPC general contracting of the ground power station project of the power grid side compressed air energy storage project in Shenneng Xilingol Xiwuzhumuqin Banner have been announced: China Energy Engineering Group Jiangsu Electric Power Construction First Engineering Co., Ltd. ranked first with a quotation of about 4.29 billion yuan, followed closely by Shanghai Electric Power Design Institute Co., Ltd. with a quotation of about 4.36 billion yuan.

6.8 billion investment, 27 month construction period, 4200MWh capacity

The total investment of the project is about 6.8 billion yuan, and the overall construction period is about 27 months. The design scale of the ground power station is 3 × 350 megawatts, with a total energy storage capacity of 4200 megawatt hours, and can provide continuous power supply at full power for 4 hours. The plan is to start production and power generation in December 2027, and complete completion and acceptance in June 2028.

On the technical route, the project adopts a non fuel compressed air energy storage solution and is equipped with a medium temperature thermal storage system. The charging time is 6.5 hours, and the system's electrical efficiency is not less than 65%, which is at a relatively high level among similar energy storage technologies. A complete charge and discharge cycle can be completed once a day, and this duration configuration is very suitable for matching the fluctuation characteristics of new energy generation.

The eastern region of Inner Mongolia, where Xiwuzhumuqin Banner is located, has abundant wind and solar energy resources, but the output of new energy is unstable. Large scale compressed air energy storage power stations can provide high-capacity, long-term grid regulation capabilities similar to pumped storage. Compared with electrochemical energy storage, compressed air energy storage has a longer lifecycle and lower operating costs, making it particularly suitable for large-scale deployment on the grid side.

From compressor unit to intelligent control system

The 4.29 billion yuan EPC general contracting of the ground power station is undertaken by China Energy Engineering Jiangsu Electric Power Construction Company, which is responsible for the entire chain of work from design, procurement to construction and installation. The main construction content includes the foundation construction and installation of compressor units, expansion units, and generator units, as well as the supporting construction of electrical systems, control systems, and various auxiliary equipment.

The ground power station will sign two separate contracts with the underground gas storage project, but they are both part of the same large-scale energy storage project. This approach of separate signing is beneficial for separately controlling construction progress and investment costs.

The non fuel compressed air energy storage technology used in the project does not require the consumption of natural gas or coal, and only relies on the compression and release process of air to complete energy conversion, with outstanding environmental benefits. The introduction of medium temperature thermal storage systems helps to improve overall thermal efficiency and ensure that the system's electrical efficiency remains stable above the threshold of 65%.

The antidote to wind and solar power curtailment and the stabilizer of the power grid

Shenneng Group chose to layout this project in Xilingol League precisely because of the abundant amount of abandoned wind and solar power in the local area and the geological conditions suitable for the construction of underground gas storage facilities.

For Xiwuzhumuqin Banner, the implementation of this project with a total investment of 6.8 billion yuan will directly drive the development of the local construction and equipment manufacturing industries. Although only a small number of operation and maintenance personnel are required during the operation of compressed air energy storage power plants, they can provide valuable rotational inertia support for the power grid - this is a physical characteristic that electrochemical energy storage cannot replace.

The design indicator of system electrical efficiency not less than 65% is at the leading level among the compressed air energy storage projects currently built and under construction in China. The application of medium temperature thermal storage technology has increased system complexity, but effectively improved energy utilization efficiency.

With the end of the pre bid announcement period, this giant "air power bank" located under the Inner Mongolia grassland will soon enter the substantive construction stage. At the end of 2027, when it is first connected to the grid for power generation, China's new power system will add a powerful 'regulating master'. Editor/Yang Beihua