It's hard when there are two countries battling it out for the most powerful in the world. In terms of renewable energy--like every other arena--China and the U.S. are fighting to lead the global economy. In terms of how attractive the countries are for investment in renewable energy projects, the two countries are ranked first and second, respectively.
Ernst and Young's biannual "renewable energy attractiveness indices"  saw little change from six months or a year ago. This time last year was when China supplanted the U.S. at the top of the list  for the first time. They've cemented their position there. Germany, which is investing even more heavily in renewables to offset the shutting down of its entire nuclear power system , leapfrogged India to take the third spot, while India slid to fourth. If you're looking for the hot new renewable country, Romania made the biggest leap (from 21st to 16th) on the strength of new programs to incentivize building wind power.
While China may be overall more attractive to renewable investors, it's doing it on the back of its wind power. The U.S. still holds, according to the report, a significant advantage when it comes to solar power. Sadly for the U.S., the investors Ernst and Young surveyed said that wind power was a far safer bet, calling it "fully bankable" and with "below average challenges." Suffice it to say, solar power was ranked by many as exactly the opposite (which makes the news of the closing of Solyndra --a U.S. solar company that received hundreds of millions in government subsidies--not so surprising).
What shakes out next will be in large part determined by what happens with the global economy, especially in the U.S. and Europe, and what--if any--comprehensive energy plan the Obama administration announces. Regardless, the horse race isn't as important as actually building the wind turbines and solar panels. Whoever can do that first will truly win.
[Images: Top, Flickr user borkur.net ; bottom, Ernst and Young]