Business of Plugging In 2010 conference, Detroit -- Some executives always hit the talking points, while others clearly relish their topic and aren't afraid to add some opinion to their presentations.

Tony Earley, CEO of DTE Corp., the parent company of Detroit Edison, is the rare public utility executive who's interesting to listen to. And today, he revealed a little nugget we hadn't known.

Detroit Edison is offering a special, experimental rate for electric-vehicle charging at home: $40 a month for all the juice your EV can use.

In other words, it's like saying you can use all the gasoline you want and pay only $40. Not bad, huh?

Earley acknowledged that the rate is subsidized. And he stressed that it's an experiment to learn whether consumers prefer flat-rate pricing for electric car charging.

The more common alternative is time-of-use rates, which make overnight charging by far the cheapest for electric-car owners, since utilities have the most excess charging capacity when most people are asleep.

Earley later threw in another nugget: Looking at the costs of installing public charging stations, he said, "the economics will never be justified" by the potential revenues a utility could recover from the station.

That led to a broader discussion about what other entities--McDonald's, Starbucks, and any number of big-box retailers--might want to install electric-car charging stations as a lure to get consumers to spend money.