Two high-ranking U.S. officials say several days of meetings with Chinese leaders on energy cooperation have been "successful" and "productive."   

U.S. Energy Secretary Stephen Chu said the purpose of his trip to China was to convey the urgency of the problem - namely a growing worldwide demand for energy, which in turn has caused faster than predicted global warming.

"I have come away with a sense that China is committed to reducing its energy intensity, reducing its growth in the use of energy, and reducing its carbon footprint, as is the United States," Chu said.

He was joined in Beijing by Commerce Secretary Gary Locke, who stressed that China and the United States, the two largest carbon emitters, have an urgent responsibility to work together to try to mitigate the problem.

"And it is my hope that China can set the new world standard for all the developing countries and the United States can set the new standard for developed countries and that together, we can work with mutual cooperation and respect, and help save the planet from this impending catastrophe," Locke said.

The two U.S. officials Thursday toured an American-made, solar-powered house in the suburbs of Beijing.  The highlight of the day was a meeting with Chinese Premier Wen Jiabao, an encounter Chu called "encouraging" and "impressive."

Besides energy cooperation, Locke said he raised other, more contentious, issues in some of his meetings with officials from China's Ministry of Commerce and Ministry of Industry and Information Technology.

These issues include the recent controversy over China's delayed requirement that all computers include an Internet-filtering software known as Green Dam Youth Escort.  Another issue was a trade dispute over poultry imports.

Locke says he has also conveyed the U.S. government's concerns over China's recent detentions of four employees of Australian mining giant Rio Tinto, on allegations they bribed Chinese officials.

Locke and Chu are both Chinese-Americans, and this issue also came up during the news conference at the end of their trip.  Locke stressed that he is, first and foremost, an American.  

"I am proud of my Chinese heritage and the contributions of China over thousands of years, but I am 100 percent American, proud of what America stands for, the land of freedom, hope and opportunity," Locke said.

Chu said he is not sure whether being ethnically Chinese hurts or helps in his efforts to forge agreements with the Chinese government.  But he said showing greater understanding of and compassion for the other side - regardless of ethnic background - is the best way to foster greater collaboration.