Is there a greener way to surf the Web?

You bet, according to Robert Hansen, CEO of SecTheory: Just tweak your Web browser so it doesn't run a lot of flashy Web graphics.

In an admittedly unscientific study, Hansen took a look at the 100 most popular sites on the Web to see which ones burned the most power on his laptop. The winner? MySpace.com, followed closely by Gamespot.com.

The sites that consumed the most power tended to use JavaScript or Adobe Flash animation, often cycling through a series of graphics over and over again. "Those technologies just were hogging all the resources on the computer," he said. "Flash banners actually seem to be the worst," he added.

The computer's CPU needs more power in order to draw the moving images created by the Web site, Hansen explained.

Even sites that appear static can sometimes quietly draw more power than expected. Apple.com's Hot Infrastructure Headlines banner, for example, uses up CPU power every time a new headline is generated, Hansen said.

Though it's not one of the top 100 most popular sites, and therefore not part of his study, the biggest power hog that Hansen came across was Mattel's Barbie Everythinggirl.com site, which easily used up a whopping 100 percent of the CPU resources on his 1.5GHz Windows XP machine with 1G byte of memory. "Barbie was absolutely pegging the CPU," he said.

Just how much power do these sites require? Hansen said that when he used Firefox's NoScript and Adblock Plus plugins to disable the moving graphics on the worst of the sites, the power consumption of his computer dropped by about 10 watts.

That's a fraction of the power used by your average lightbulb, but it's still more than green computing consultant Tom Block expected. "Ten watts seems like a lot when all we're doing is pulling a Web page," said Block, who is president of Block Data Systems.

Hansen said Web developers can be more environmentally responsible by reducing the amount of animation on their sites, but he admitted there may be a downside: less traffic, because Web surfers respond to flashy graphics.

Hansen isn't the first to look at what Web sites can do to reduce power consumption on their visitors' computers. Last year the Web site Blackle.com launched, saying that people could save energy by switching their home page from Google.com to a page with a black background such as Blackle.com. The idea was that a black Web page required less energy to illuminate than a white one.