Here are some highlights of FORTUNE’s Brainstorm Green conference, which wrapped up yesterday. I’m co-chair of the event, which brought about 300 corporate leaders, environmentalists, investors and academics to Laguna Niguel, CA, for three whirlwind days of talk about how business can help solve the world’s big environmental problems:

The trouble with electric cars: Batteries remain heavy and very expensive, adding about $12,000 to $15,000 to the cost of a Ford Focus that would otherwise be priced at about $22,000, said Ford’s CEO, Alan Mulally. During a q-and-a with the audience, he said:
…a battery for a hybrid vehicle is around a 2 kilowatt hour battery, weighs around 100 pounds, maybe around $2,000. And as you move to a plug-in hybrid size, say around 8 to 10 kilowatt hours, then that weight moves up to around 300 pounds and the cost is around $7,000 to $8,000. And then when you move into an all-electric vehicle the battery size moves up to around 23 kilowatt hours, it weighs around 600 to 700 pounds — some people actually are taking our seats to be able to carry the battery around, not us — and also they’re around $12,000 to $15,000….So, you can see why the economics are what they are.
Of course, drivers who pay $39,200 for a Focus EV will save a lot of money on fuel during the life of the car, depending on gas prices and how much they drive. That’s a reminder of another dilemma facing potential electric-car buyers. Ford says its Focus can go up to 76 miles on a full charge, so it’s ideal for people (like me) who don’t drive much. But the less you drive, the longer it takes to recover the higher up-front costs of the car in the form of lower operating costs.
Even so, sales of hybrids and electrics were the fastest-growing segment in the U.S. auto market in the first quarter. They accounted for less than 5% of vehicles sold but Mulally said their share will grow as battery prices come down.
“We see this as continually growing,” he said. “This is a long-term journey.” [click to continue…]