China is emerging as the world's clean-energy powerhouse, according to the Pew Charitable Trusts.

Last year, China spent more than any other major country on clean energy, including wind and solar, toppling the U.S. from the top spot for the first time in five years, the Pew report says. The U.S. is also on the verge of losing the top spot in terms of installed renewable energy to China.

Unless U.S. policies change to encourage more investment, the U.S. could miss its chance to lead the expanding clean-energy industry, says Phyllis Cuttino, a project director at Pew. U.S. entrepreneurialism and strengths in innovation give it the potential to recoup leadership, the Pew report says.

Energy Secretary Steven Chu noted in congressional testimony late last year that the U.S. "has fallen behind" other countries in the race to be at the forefront of the clean-energy industry. Although Chu said he was confident the U.S could make up the ground, he cited China as a formidable competitor.

In recent years, China has emerged as the No. 1 maker of solar cells for solar panels and, most recently, as the leader in wind-turbine-making capacity. China's leaders have also set in motion plans to get 15 percent of the country's energy from renewable sources by 2020.

The Pew report, using data compiled by Bloomberg New Energy Finance, examined the world's top 20 economies. It found that:

• From 2005 through 2009, China's clean-energy investment, including wind and solar, soared 148 percent vs. 103 percent for the USA.

• Clean-energy investment in Asia, mostly China, rose 37 percent last year to $39 billion. Investment declined 33 percent last year in the Americas as economies slowed and credit tightened.

• Ten of the leading economies devoted a greater percentage of gross domestic product to clean energy than the U.S. in 2009.

The U.S. has no national standard for expanding renewable energy. Proponents say a national standard would help manufacturers prepare for a big U.S. market for their products. The U.S. has also offered on-again, off-again financial incentives for renewable energy while other countries' support has been steady.

U.S. incentives "need to be 10 years in length" to encourage investment, Cuttino says.