Bob Metcalfe is a colorful character and Internet pioneer. He invented the Ethernet, founded a big tech company called 3Com and even has a law named after him: Metcalfe’s Law says the value of a network is proportional to the square of the number of its connected users, an interesting notion but one that strikes me as unprovable.

In any event, Metcalfe is now a venture capitalist with Polaris Venture Partners focused on clean technology, and he’s been traveling around giving a slide show, drawing lessons from the Internet that can be applied to clean tech. His ideas are the subject of today’s Sustainability column at fortune.com.

Here’s how the column begins:

Back in the 1960s, when Bob Metcalfe was in college, he would drive to MIT in Cambridge, Mass., from his home in Brooklyn, call home once he arrived, allow the phone to ring three times and hang up, to let his mother know he’d arrived safely.

“The long-distance call was so expensive that mom didn’t want to pay for it,” Metcalfe recalls. “She loved me a lot — but not that much.”

Today, of course, phone calls cost nothing on evenings and weekends and, using Skype, you can call anywhere in the world for free or just pennies a minute. Information — phone calls, baseball scores, this column, Wikipedia — has become cheap and easy to find because of the telecom and Internet revolutions, which created an abundance of low-cost bandwidth.

Metcalfe helped drive those revolutions, and now, as a venture capitalist with Polaris Venture Partners in Cambridge, he wants to help engineer another revolution, this one in energy.

Metcalfe is a provocative thinker. You can watch his slide show here. And you can read the rest of my column here.