General Electric is promoting a feel-good collection of videos these days.

Called “Focus Forward,” it promises “short films, big ideas.” Each of these mini-docs triumphantly chronicles an innovative idea, like Daniel Nocera’s. This Harvard chemist has pioneered the artificial leaf, an invention that generates energy more or less the way a tree does. Light strikes a container of water and out bubbles hydrogen, an energy source.

The three-minute film about his idea blazes with shafts of light spangling off leaves, and its soundtrack clocks more crescendos per minute than a high-school cello recital. There are many low-angle shots of a towering Mr. Nocera telling us that his device will one day be in people’s homes, pumping out energy.

“Close your eyes,” the colossus says, and “think about your house being its own power station.”

Here’s the thing: Such artificial-leaf optimism could also be found a year ago in a Los Angeles Times article that held the artificial leaf “could create enough clean fuel to power a home for a day in developing countries.” And the year before that, in The New Yorker, where Mr. Nocera said the artificial leaf would “turn a home into ‘a self-sufficient power station.’ ” Or go back one more year, to the pages of The New York Times, where Mr. Nocera said, “Our goal is to make each home its own power station.”

So, all right already. Where’s my power station?

Prowl the edges of contemporary invention, and you experience a lot of this frustration. A scientist announces a breakthrough in, say, battery technology or algae biofuel, and the talk ramps up quickly to full-throttle utopian, tapping into a frontier dream that’s so alluring to Americans: energy from light, self-sustaining, untethered from the grid.