"Renewable energies are no longer subject to the vagaries of rising and falling oil prices -- they are becoming generating systems of choice for increasing numbers of power companies, communities and countries," said Achim Steiner, head of UNEP.

UNEP said investment capital flowing into renewable energy and efficiency technologies rose 25 percent in 2006 to US$100 billion from US$80 billion in 2005. That total was likely to leap to around US$120 billion in 2007.

Growth "although still volatile...is showing no sign of abating", the report said.

Steiner said the report showed industries in rich countries were no longer dominant in renewable energies such as wind, solar, biofuels, hydro, tidal or geothermal power.

Almost 10 percent of the 2006 investments were in China, he said. India was the biggest net buyer of companies abroad in 2006, led by takeovers by Indian wind turbine maker Suzlon which is planning a European listing.

The report said worries about climate change, high oil prices averaging more than US$60 a barrel last year, efforts to break dependence on energy imports and government incentives to shift away from fossil fuels had spurred investment.

WIND, BIOFUELS, SOLAR

The report, prepared by UNEP with London-based New Energy Finance, said the wind sector won most investment with 38 percent of the total, ahead of biofuels on 26 percent and solar power on 16 percent.

Renewable energies are a key to fighting global warming, widely blamed on greenhouse gases from burning fossil fuels. A UN panel has projected that emissions will cause more floods, droughts, disease and rising oceans.

Of the total of US$100 billion, the report said US$71 billion included initial public offerings and spending on research and development of sustainable energy while mergers and acquisitions added almost US$30 billion.

UNEP noted that gains by many renewable energy stocks had far outpaced rises in world stock markets in recent months but toned down comparisons with Internet stocks which surged in the late 1990s before the dot-com collapse in 2001.

Unlike dot-com firms, the report said renewables were based more solidly on existing technology, that many companies were generating strong revenues and had regulatory support.

"Betting on companies that already have technologies is easier than betting on companies that are developing the technologies of the future," Eric Usher, head of UNEP's Energy Finance Unit in Paris, told Reuters.

The report said that renewable energies accounted for 18 percent of investment in world power generation, or US$21.5 billion, compared with 2 percent of installed capacity.