China's coal-abundant Shanxi rationed electricity as the province reported the most severe power shortage in three years as the current coal output fell short of demand drove up by the prolonged icy weather.

Two major thermal power plants in the capital city of Taiyuan, namely the branch factories of the China Guodian Corporation and the China Datang Corporation, saw power coal reserves enough for less than the warning level of seven days of use.

The bitterly cold weather pushed up demand for resident heating, which prompted a power shortage of near 500,000 kilowatts, local power supply authority has said.

The municipal government has ordered rotating shutdowns of more than 40 power-guzzling factories to ensure sufficient power supply to residential use.

Outdoor landscape lighting was also turned off during the peak time of power use.

Although having one third of the nation's coal reserves, Shanxi faced coal shortage due to insufficient production and hefty amount of coal outflow to other parts of the nation, Li Jianwei, deputy director-general of the provincial electricity association told Saturday's 21st Century Business Herald.

The closure of small pits drove down the coal output, while the production of the large-scale state-owned factories could not make up for the gap, he said.