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.

It was announced that the exploration produced more than 300,000 cubic meters of gas, mainly methane, with an average daily extraction of more than 5,000 cu m of high-purity gas, and a highest daily output of 35,000 cu m.

"What we are seeing is that the natural gas industry is in transformation," Birol said. "We are seeing more and more unconventional gas being part of the total gas mix."

In a report released at the 22nd World Petroleum Congress in Istanbul on Tuesday, the IAE said that as the world's largest energy investor, China saw a 25 percent decline in coal-fired power investment last year and is increasingly driven by clean electricity generation and networks, as well as energy efficiency investment.

The agency expects China to overtake Europe within a few years in terms of energy-efficiency investment, as the country has replaced Japan as the world's top investor on energy research and development as a share of the GDP.

"China continued to dominate renewables growth, contributing about 40 percent of global growth - more than the entire OECD (the Organization for Economic Cooperation and Development) - and surpassed the United States as the largest producer of renewable power last year," BP chief economist Spencer Dale said in the report.

Global hydro power rose 2.8 percent in 2016 from a year ago, with more than 40 percent of the growth from China, according to the latest BP Statistical Review of World Energy released on Monday.

In the meantime, global nuclear power went up by 1.3 percent, with China contributing almost all the growth, the report said.

The BP data showed carbon emissions in the world rose slightly by 0.1 percent in 2016, while in China emissions fell 0.7 percent from a year ago.

"Today China is number one in terms of wind power, number one in terms of solar and number one in terms of the energy-efficiency effort as well as in nuclear power," Birol said.

Energy investment around the world amounted to $1.7 trillion last year, accounting for 2.2 percent of global GDP, the IEA report said, noting that spending on the electricity sector worldwide exceeded the combined spending on oil, gas and coal supply for the first time.

"Our analysis shows that smart investment decisions are more critical than ever for maintaining energy security and meeting environmental goals," Birol said in the report.

Xinhua