The mainland is bracing for power cuts this summer, although they are likely to be less severe than last year, when 24 provinces and municipalities were affected, a senior official says.
The shortfall during the peak season, beginning next month, is projected at 25 gigawatts, slightly less than last year's figure.
Shi Yubo, of the State Electricity Regulatory Commission, said an increase in generating capacity of about 65gW planned for this year would not provide relief over the summer because most of it was not scheduled to come on stream until the second half of the year.
The expansion would push the country's total generating capacity to 505gW, against 2,422 terawatt-hours of total electricity consumption - up 12 per cent on last year.
Apart from the northeastern provinces, all other power grid areas face shortfalls. In the east, it has been estimated at 12gW, and in the south at 8gW.
Mr Shi said the weather could make a significant difference to power consumption and supply.
With urban areas becoming more affluent, the use of air conditioners accounts for up 30 per cent of electricity consumption in Beijing, and as much as 40 per cent in Shanghai and Guangzhou.
The amount of water available for hydroelectric generation also depends heavily on the weather.
In Beijing, which relies on supplies from local power plants and electricity purchased from Shanxi , the northeast and Inner Mongolia , a deficit of 0.7gW has been projected for this summer.
Mr Shi said that if the weather turned out to be neither too hot nor too humid, the capital would probably be spared widespread blackouts.
The commission has used price rises in a bid to curb the expansion of industries that consume high levels of power, while keeping a lid on rates for farmers, and small- and medium-sized fertiliser plants.
Mr Shi said that the mainland's power grid system, operating without any reserve capacity and with no downtime for maintenance, was vulnerable to technical breakdowns.
Typhoons, heavy rain and criminal activities could also disrupt power supplies, and the authorities were stepping up control and prevention measures.