BEIJING - As the development of clean energy reaches record levels, China, the world's largest energy investor and innovation center, has made stronger-than-expected efforts to accelerate the development.

Fatih Birol, executive director of the International Energy Agency, on Tuesday lauded China's efforts in the research and development of clean energy, saying "China takes once again the leadership".

On Sunday, China completed a 60-day trial of mining gas hydrates, commonly known as combustible ice, in the South China Sea, marking a breakthrough in the search for alternative clean energy resources.