China vowed to set up a coal capacity reserve system by 2027, aiming to secure energy security through more flexible coal supplies, according to plans the country released Friday.

By 2030, the country will strive to attain a yearly coal capacity reserve of 300 million tonnes that are dispatchable and improve the capacity and flexibility of coal supplies, according to a document jointly released by the National Development and Reform Commission and the National Energy Administration (NEA).

The establishment of the coal capacity reserve system will enable the rapid release of coal production capacity in extreme situations, such as severe fluctuations in the international energy market, adverse weather conditions, and dramatic changes in supply and demand stability, guaranteeing sufficient coal supply in these circumstances, according to an official with the NEA.

The system can also better leverage coal-fired power's underpinning role in power generation, promote the high-quality development of new energy, and facilitate the green and low-carbon transformation of the energy industry, the official added.

Coal has long been China's mainstay fuel. China mined 4.66 billion tonnes of coal last year, up 2.9 percent from the previous year, reaching a record high.

The coal capacity reserve is only reserved for extreme situations and remains inactive under normal conditions, according to the NEA.