Oct. 13--Amid frigid fundraising conditions for the venture capital industry, an announcement from finance mogul George Soros represents another billion-dollar ray of sunshine for the booming clean-tech sector.

Soros, known for putting his money where his mouth is on social and political causes, announced in Copenhagen over the weekend that he would commit more than $1 billion of his fortune to clean-energy investment and political efforts to tackle the climate change crisis.

Soros' money could help promising startups "get through what we call the valley of death," said Paul Holland of Foundation Capital, a Silicon Valley venture firm known for clean-tech investments. The phrase, common in the venture industry, refers to the difficulty of taking a proof of concept to a scale sufficient for a profitable business.

Soros' commitment is roughly equivalent to the dollars raised in two funds recently announced by Khosla Ventures, the Sand Hill Road firm known for its interest in experimental clean-tech startups.

Interest in clean tech drove much of venture fundraising in the most recent quarter. Across all categories, $1.6 billion was raised by 17 venture funds during the quarter, according to the National Venture Capital Association and Thomson Reuters.

It was the smallest number of funds raising money in a single quarter since 1994, when 17 were also raised, and the lowest level of dollars committed since the first quarter of 2003, when $938 million was raised.

Soros' specific clean-tech investment strategy is unclear, but Jim Watson, managing general partner of CMEA Capital of San Francisco, noted that Soros has already made investments in capital intensive technologies such as carbon sequestration and so-called "clean coal" efforts. Soros' commitment, he noted, represents a small fraction of the many billions of dollars that the clean-tech industry will require in the coming years.

Given the size of Soros' commitment and his acumen in finance, not technology, it seemed likely that Soros would focus most of the money of later-stage clean-tech companies with proven technologies, Watson said. Soros could be positioned to make so-called "mezzanine" investments to help position mature startups for initial public offerings on Wall Street.

Holland agreed, saying Soros could help provide necessary "money in the middle" that is not sufficiently addressed by clean-tech investors now.

Soros, 79, is a Hungarian-born hedge fund manager who was recently ranked by Forbes magazine as the 15th-richest American, with a fortune estimated at $13 billion.