At the Serve to Preserve climate change summit in Miami, we’re being told by our governor that the state of Florida is going to get greener through volunteerism, told by a Kennedy how bad the Bush administration’s environmental record is and by Teddy Roosevelt’s great-grandson how, no matter what we do, we’ll always be dependent on oil so we have to marketize carbon emissions.

But Vinod Khosla, the co-founder of Sun Microsystems and head of Khosla Ventures, actually told us some things that make real sense, as well as some that seem unthinkable.

Khosla is really smart, and he has a track record to prove it. A few years back, he sat down with the major phone companies and told them that the Internet would make long-distance phone calls free. He was right and AT&T went out of business for a while. In 1996 he told nine of the top 10 newspaper organizations — Tribune Co., Knight-Ridder, etc. — to watch the Internet because innovations were coming that would impact their industry. Today, Google is worth more than all the still-existing newspaper companies combined.

So if I could, I’d follow Khosla around and bet on any horse he placed a bet on. He’s what they call a visionary.

While Theodore Roosevelt IV of Lehman Brothers proposes a classic market-based approach to global warming where technological advances will be encouraged by a marketplace based on carbon caps and trading — in other words a fossil fuel-based economy — Khosla says that within 25 years we can end our dependence on oil completely.

A world economy that’s not dependent on oil? Unthinkable! Yet Khosla says that there is some innovator out there who, today, tomorrow, next year, will create the next technological breakthrough that will enable us to end our addiction to oil.

“Oil is replaceable by cheaper alternatives,” said Khosla. “The danger is that as we wean ourselves off oil, the price will fall, which will slow the technical innovation away from oil.”

But Khosla says that we already have made incredible strides toward efficiency, we just don’t realize it. “The U.S. economy, in terms of energy efficiency, is saving $750 billion per year of gross national product when compared to our energy usage in the 1970s.”

Khosla advocates a complete change in our approach: “Green isn’t a choice, it’s deciding which risks we want — higher start-up costs and lower eventual costs, more jobs and more Googles or more of the same, competition for energy or a safe oil supply,” he said.

“All we need to do is change our mindset,” said Khosla. “We need to encourage the innovators and the unthinkable of today will become the commonplace of tomorrow.”