A maintenance worker in ChinaA maintenance engineer inspects a wind turbine in Guangdong, China. Photo: Greenpeace InternationalA day after Energy Secretary Steven Chu’s “Sputnik speech,” in which he warned that China was investing billions in renewable energy while American politicians bickered over small-potatoes stimulus spending on green technology, a report from Ernst & Young released Tuesday confirmed Asia’s ascendancy.

“A new world is emerging in the clean energy sector with China now the clear leader in the global renewables market,” the report’s authors wrote.

Ernst & Young publishes a quarterly “country attractiveness” index for investors that ranks nations’ renewable energy policies, renewable energy markets, and other factors.

China took first place — again — ousting the U.S. from the spot it had occupied between 2006 and 2010.

“China’s record spending on its wind industry this quarter represented nearly half of all funds invested in new wind projects around the world,” the report states. “Figures released for the second quarter of 2010 showed that China invested around $10 billion in wind out of a global total of $20.5 billion.”

Half the wind turbines that will come online this year worldwide will have been made in China, according to the report.

“Since reaching top spot in our index in September, China has opened up a healthy gap from other markets,” Ben Warren, an Ernst & Young executive, said in a statement. “Cleantech, including renewable energy, represents a significant part of the country’s future economic growth plans.

“The level of wind energy being deployed in China shows what can be achieved with a carefully planned energy and industrial policy that elevates cleantech to a national strategic level,” he added. “The Chinese solar industry is also fast becoming of great importance in the global marketplace.”

And China clearly has its eye on the U.S. market. As I wrote last week, one of China’s largest solar companies has formed a joint venture with California startup SolarReserve to build photovoltaic power plants in the desert Southwest.

And it’s not just China the U.S. has to worry about in the green energy race. According to Ernst & Young, South Korea, Romania, Egypt, and Mexico are rising fast as their governments devote more resources to renewable energy.