With two laptop-loving children and a Jack Russell terrier hemmed in by an electric fence, Peter Troast figured his household used a lot of power. Just how much did not really hit him until the night the family turned off the overhead lights at their home in Maine and began hunting gadgets that glowed in the dark.

“It was amazing to see all these lights blinking,” Mr. Troast said.

As goes the Troast household, so goes the planet.

Electricity use from power-hungry gadgets is rising fast all over the world. The fancy new flat-panel televisions everyone has been buying in recent years have turned out to be bigger power hogs than some refrigerators.

The proliferation of personal computers, iPods, cellphones, game consoles and all the rest amounts to the fastest-growing source of power demand in the world. Americans now have about 25 consumer electronic products in every household, compared with just three in 1980.