Is there considerable energy saving using a black background on my website?

Solution 1:

No, it doesn't save power. http://googleblog.blogspot.com/2007/08/is-black-new-green.html

You can save power by turning down the brightness of your screen, or (obviously) by turning it off when you're not using it.

Solution 2:

You would expect a black background to save power on a purely emissive display such as actual LED (as opposed to LED-backlit LCD), OLED or plasma. CRT I'm not sure about because I don't know exactly how it dims the electron beam.

However, the most common type of computer monitor these days is LCD, which as others have pointed out, actually uses energy changing the LCD to absorbing mode to make pixels black.

Solution 3:

Yes, it can save power on the AMOLED screens used on Google's Nexus One, the HTC Incredible, and other mobile phones. Linky

Solution 4:

There is some power savings with a large CRT. I had a 19" CRT (now sitting in the bottom of a closet due to being replaced by a 22" widescreen LCD) hooked up to a UPS, and with the computer in an idle state showing a mostly black screen would have 2 of the 5 load indicator LEDs lit, but a partially white screen would bump it up to 3.

Now, could this be called "considerable"? Not likely. But it is more than none.