Datang International Power Generation Co Ltd (Datang Power) reported a 110 million yuan ($16.7 million) deficit last year, and sources said the deficit is a result of the high cost of thermal power generation, the 21st Century Business Herald reported Wednesday.

"The losses on the thermal power business are getting worse. The more power generated, the more money is lost," the newspaper reported, citing sources. Datang Power is the only one of China's big five power groups that failed to realize a profit last year.

The big five power groups are China Huaneng Group, China Guodian Corp, China Power Investment Corp, China Huadian Corp, and Datang Power.

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Cost on standard thermal coal delivered to the big five power giants increased an average of 17 percent or 118 yuan per ton last year, the report said, citing data.

"Datang Power bought some non-profitable plants in its expansion around 2008, increasing its installed capacity to more than 100 million kilowatts (kW). But now it has become a huge burden with the case of the thermal coal price rise," the sources said.

The company's installed capacity was 105.8 million kW last year, second to China Huaneng Group's at 113.4 kW.

China Huaneng Group's 4.2 billion yuan net profit topped the profitability ranks last year among the big five. China Guodian Corp's 3.75 billion yuan ranked second, followed by China Power Investment Corp's 3.39 billion yuan, and China Huadian Corp's 1.75 billion yuan.