ndian American Silicon Valley billionaire Vinod Khosla tops the list of 10 greenest billionaires chosen by Forbes "who are most active in green, sustainable causes and who are working to have the greatest impact."

The leading US business magazine said it found the top ten "are altruistic, yes, but most of them are also very much aiming to turn a profit" and they hail not just from the US but also from Israel, Germany and Canada.

"Khosla-a cofounder of Sun Microsystems and a longtime partner at venture capital powerhouse Kleiner Perkins Caufield & Byers-has, with fellow billionaire and green business supporter John Doerr, been pouring millions of dollars into green tech companies," Forbes noted.

The magazine put Khosla's net worth at $ 1.1 billion and Doerr's at $ 1.7 billion, noting in 2004 Khosla began, though his Khosla Ventures, to fund dozens of innovative companies involved in areas such as sustainable building materials, solar power and advanced biofuels.

Some of these investments Khosla has described as "science experiments" that may or may not succeed, it said.

"I like Vinod's strategy because traditionally VCs don't buy into companies at their early stage. He does, and the science experiment that survives that germ-of-an-idea stage has a good chance it'll be mainstream some day," Forbes quoted Michael Kanellos of Greentech Media as saying.

Ausra, a solar thermal power company backed by Khosla Ventures and Kleiner Perkins, had trouble getting financing and permits for planned solar plants and in 2009 switched its focus to selling equipment for customers that included coal-fired plants.

Now the company is out of Khosla's purview as in February French nuclear giant Areva bought Ausra for an undisclosed sum.

But Khosla has plenty of other green tech bets, including Calera, a company that is developing technology to trap carbon dioxide and capture it in cement, Forbes.

Among others making Forbes greenest billionaires list were Israeli Carnival Cruises heiress Shari Arison, Google cofounders Larry Page and Sergey Brin and German billionaires Aloys Wobben and Prince Albert von Thurn und Taxis.

Nearly everyone wants to be green these days, or so it seems, said Forbes noting more than $ 200 billion globally will be invested this year in sustainable businesses-a 40 percent increase from 2009.