Last year the United States attracted more private investment in clean energy than any other country, according to a report released today by the Pew Charitable Trusts, “Who’s Winning the Clean Energy Race?” But the findings suggest this was largely because of tax incentives that either have just expired or will expire soon, so the U.S. might not carry this lead into 2012.

The report is a useful resource that outlines where clean-energy investment is going: which countries, which forms of energy, and what types of investment, whether early-stage funding to startups or large-scale project financing.

However, it does make one unfair comparison. It says that 565 gigawatts of renewable energy are installed worldwide, including sources such as solar, wind, and small hydroelectric power (but not large dams). It says this is 50 percent more than the total installed nuclear capacity, but that’s misleading. Renewable energy might have a higher rated capacity, but these technologies produce power only about a quarter of the time, because wind and sunlight are intermittent. Nuclear power plants, which run night and day, actually generate more electricity.