Used to be, moms would tell their kids to shut the refrigerator door to save electricity. Well, the modern equivalent might as well be, “Shut down that PlayStation, Junior!”

Just in time for Earth Day (April 22) comes this report from the research gurus at Carnegie Mellon University: Apparently 68 percent of the energy consumed by game consoles in the U.S. in 2010 was spent while the devices were idle or sleeping. In other words, an awful lot of people play, then just walk away when they’re finished without powering off.

Okay, sure, 68 percent sounds huge, but not everyone has a gaming console. So it can’t really amount to that much, right? Wrong. The power squandered here equals about 10.8 TWh of energy, or roughly $1.24 billion worth of electricity. [Insert *gasp* here.] Seriously, this is not the kind of leveling up you want to do.

Well, at least Xbox 360 users stand in slightly better stead. These consoles have auto-standby that kicks in if the machine’s left idle for over an hour. The PlayStation 3, kinda-sorta does: Users can perform a software update to get a power-management feature, but it’s disabled by default. They have to manually activate it. Either way, it’s still drawing a load, so the best way to save energy is to unplug the device when you’re not using it. If not, then at least power it down when you’re done.

Do you leave your console on after a session, or do you shut it off each time? Hit our poll and let us know.

[via CNET]