Approval obtained on coal-fired air-cooling power generation project of Zioquan Power Plant

Huaneng Power Int. (NYSE:HNP) (HKG:0902)

Huaneng Power International, Inc. (NYSE:HNP) (the “Company”) announced that the project of two 600MW domestic supercritical coal-fired air-cooling generation units (the “Project”) of Shanxi Huaneng Zuoquan Power Plant (in which the Company holds 80% interests) was recently approved by the National Development and Reform Commission.

The Project will install electrostatic precipitators, desulphurisation, denitrification and on-line flue-gas ongoing monitoring system. Emission indices at the power plant will meet the State’s prescribed requirements on environmental protection.

The total investment amount of the Project is estimated to be approximately RMB5.09 billion, of which 20% is equity capital which is to be contributed by the Company and Shanxi International Electricity Group Limited Company according to the capital contribution ratio of 80% and 20%, respectively. The remaining investment will be funded by bank loans.

By Order of the Board

Huaneng Power International, Inc.

Gu Biquan

Company Secretary

The Company achieved a total net production of 80.9 million barrels of oil equivalent (BOE) for the third quarter of 2011, representing a decrease of 9.1% year over year (YOY). The decline in net production was mainly attributable to the production loss as a result of the suspension of production of Penglai 19-3 oilfield in Bohai Bay as well as the natural decline of certain producing fields. For the third quarter of 2011, the Company made two new discoveries and nine successful appraisal wells.

Having benefited from higher realized oil and gas prices, the total unaudited oil and gas sales revenues of the Company reached approximately RMB46.26 billion for the third quarter of 2011, representing a significant increase of 23.7% YOY. In the third quarter of 2011, the Company’s average realized oil price significantly increased 50.3% YOY to US$112.04 per barrel while the Company’s average realized gas price increased 20.0% YOY to US$5.18 per thousand cubic feet.

For the third quarter of 2011, the Company's capital expenditure was approximately RMB10.55 billion, representing an increase of 28.8% YOY, mainly attributable to the busy development pipeline and extensive exploration program.

For the purpose of this announcement, unless otherwise indicated, an exchange rate of US$1 = RMB6.4147 has been used for the third quarter of 2011, and an exchange rate of US$1 = RMB6.7772 has been used for the third quarter of 2010, where applicable. The usage of these exchange rates is for illustration only and does not constitute a representation that any amount has been, could have been or may be exchanged or converted at the above rates or at any other rate at all.

This announcement is published on the website of The Stock Exchange of Hong Kong Limited (http://www.hkex.com.hk) and on the Company’s website (http://www.cnoocltd.com).

By Order of the Board

CNOOC Limited

Jiang Yongzhi

Joint Company Secretary