CHONGQING, May 30 (Xinhua) -- Construction will start on two more underground gas storage facilities in southwest China's Chongqing Municipality by the end of this year, PetroChina Southwest Oil & Gas Field Company said Wednesday.

The total cost of the Tongluoxia and Huangcaoxia facilities will be 5.3 billion yuan (830 million U.S. dollars) and they will be completed by 2022, ensuring an annual supply of 1.28 billion cubic meters of gas.

Underground gas storage facilities are used to level off daily gas consumption fluctuations and meet peak demand in winter. China has around 25 such facilities nationwide.

Chongqing has stable geological structure and makes an ideal location to store gas underground, said Wen Ming, assistant general manager of PetroChina Southwest Oil & Gas Field Company.