[bhhaskin]

The largest power drain in an LCD/LED screen is the backlight and that has to be running regardless of which color is being displayed. This would only benefit OLED screen (which doesn't have a normal backlight) which are pretty much only used on high-end phones and TVs. Unlikely to make a significant impact in energy use, and furthermore any amount of energy savings would likely be lost in the extra amount of black ink needed to print out pages.