San Francisco: Venture capitalist Vinod Khosla is placing his bets on alternative technologies that could potentially make at least 80% of global energy consumption cleaner in the next few years.

Speaking during the Reuters Global Environment Summit, Khosla said he hunts for “black swans” in alternative energy — revolutionary and unforeseen ideas that change the world as we know it — and are as unexpected as the birds they are named for.

“There is no such thing as great visionaries,” said Khosla, one of Silicon Valley’s best-known venture capitalists. “There’s a huge dose of luck... we just have to take more shots on goal.” Khosla said, Nassim Taleb, a Wall Street trader-turned-author uses the term “black swan” in a recent book to describe the unpredictable and consequential events in business that can be clearly explained once they happen, such as the current financial crisis. But the world of technology creates opportunities for “good” black swans, added Khosla, dressed in his trademark all-black outfit.

Khosla Ventures, the venture capital firm he founded in 2004, has alternative energy investments across the spectrum of wind, solar, biofuels and geothermal energy.

The firm also invests in cleaner battery technology and cleaner building materials; Khosla said he expected more than half the firm’s investments in 65-odd start-up companies to succeed.

Biofuels made from non-food based natural sources and waste were among the most promising sources of scalable clean energy alternatives, Khosla said. “Four years ago, when I said biofuels were interesting, people told me don’t be flaky,” he said.

An Indian-American who came to the US as a student in the 1970s and is a fixture on Forbes magazine’s list of billionaires, the co-founder of Sun Microsystems Inc. said he is happiest poking around for the next big idea and chatting with entrepreneurs.