Bill Gates, whose philanthropy is aimed at improving the lives of people in poor countries, is also taking a interest in clean energy, both intellectually and financially.
In an interview published Sunday, Gates said he has invested in Vinod Khosla's green-technology fund, which is aimed at incubating breakthrough technologies.
"He is backing some great entrepreneurs. I get some exposure to them as part of that. Innovation is called for in a big way," Gates said.
After leaving full-time work at Microsoft in mid-2008 to focus on the Bill and Melinda Gates Foundation, the software pioneer had been relatively quiet on the topic of energy and climate.
His publicly disclosed investments in energy include algae fuel company Sapphire Energy. He was invested in Pacific Ethanol but is now divested from it. With former Microsoft CTO Nathan Myhrvold, Gates is also backing TerraPower, which seeks a breakthrough in the design of nuclear power plants.
Last week, though, Gates launched his Gates Notes Web site, where he collects his big-picture thoughts on issues he has been studying. Energy and environment are high on the list of topics there, in part because they closely relate to his philanthropic goals, Gates said.
"For rich people, yes we can use less energy, we can afford a higher price. For the poor, a higher price of energy would mean that their life would be much worse. They couldn't afford as much fertilizer, they couldn't get to their job, they can't get clean water. So the progress of civilization has depended on and will depend on energy being cheaper. But now we have this constraint of not just less CO2, but no CO2."
Gates said that most new clean-energy companies will fail. "But all we need is a few to succeed to take on both helping the poor and getting the climate change problem under control."
The Khosla Fund, led by famed investor Vinod Khosla, is one of the largest green-tech funds formed in the past year, having raised over $1 billion with much of dedicated energy and materials technology.
Khosla has been an aggressive investor in a wide range of technologies, including biofuels, energy efficient lighting, and cleaner industrial processes, such as low-polluting methods for making cement.