BEIJING—Earnings for China’s power utilities during the first three quarters of 2021 have plunged as the companies were squeezed by surging coal costs that they could not pass on to consumers. Huadian Power International, a subsidiary of China Huadian Corp., on Tuesday reported profits for the January-September period dropped 58 percent from a year earlier to 1.6 billion yuan ($251 million) with a third-quarter loss of 1.8 billion yuan. Huaneng Power International, a listed arm of China Huaneng Group, also said their earnings in the first nine months of the year dropped 91 percent year-on-year to 783.9 million yuan, with a third quarter loss of 3.5 billion yuan. Both companies blamed the losses on cost increases from a surge in power demand, while at the same time coal prices jumped with Huadian saying in its statement, “The decrease in net profit was mainly due to the surge in the price …