Worldwide cleantech investments jumped 60 percent in 2007, reflecting a “green energy gold rush,” the United Nations reported Tuesday.

Investors pumped $148 billion into new renewable energy projects last year, compared with $92.6 billion in 2006, according to a report by the U.N. Environment Program (UNEP). In 2005, greentech investments reached $58.5 billion.

Wind-energy projects received the most money in 2007, getting $50 billion, a 40 percent spike from 2006, according to the report. Butsolarinvestments grew the fastest, increasing 90 percent to $28 billion.

"Just as thousands were drawn to California and the Klondike in the late 1800s, the green energy gold rush is attracting legions of modern day prospectors in all parts of the globe," said Achimv Steiner, head of the UNEP, in a written statement.

Different groups have released varying investment figures for 2007, as some track different kinds of investments or use different definitions for green or clean technology.

Greentech Media’s Venture Power Report, which tracks only venture-capital investments, reported 48 percent growth to $3.4 billion in renewable-energy funding.

The U.N. report, prepared by the London-based New Energy Finance, said Europe raised most of the money, followed by the United States. But other major contributors to greenhouse emissions, such as China and India, are also spending money to develop renewable energy technologies.

The UNEP said China’s preparation for the 2008 Olympics prompted the government to support more renewable energy projects. Chinese solar companies raised $2.5 billion from stock markets in the United States and Europe. As an example, Chinese wind-power company Goldwind raised $243 million through an initial public offering on the Shenzhen Stock Exchange.

And on Monday, India’s Prime Minister Manmohan Singh introduced the country’s fist plan to reduce human impact on climate change. The plan laid out eight goals that included using more solar energy and water conservation.

India is the fourth largest generator of carbon dioxide, after the United States, China and Russia, according to the World Bank.

This year may not be great for companies seeking investments, however. Several ethanol companies in the United States have had cancel or scale-back proposed plants, and no venture-backed IPOs took place in the U.S. market during the second quarter, for the first time since 1978 (see Green Light post).

Some Chinese solar companies also are having cash-flow problems, leading to one analyst from Goldman Sachs to downgrade Trina Solar on Tuesday (see LDK Confirms Plant Is On Track).