From Nov 09 CNET
No discussion of TV power use would be complete without a bit of perspective. For households that pay somewhere near the average retail cost for energy--11.36 cents per kilowatt per hour in 2008--and that watch near the average amount per TV--about 5.2 hours per day--the cost to watch a 50-inch 1080p plasma TV is about $63 per year in the calibrated light output mode (see How We Test). A typical 52-inch LCD TV costs about $27 per year for the same light output, and of course, smaller TVs use less energy. Sure, both electricity costs and average daily TV use are increasing steadily every year; however, those amounts still don't take a major chunk out of most household budgets. According to the Department of Energy, for example, the average refrigerator uses nearly $90 worth of energy per year.
It's worth noting that plasma TV has many picture quality advantages over LCD TVs, so people who really prize video quality may be willing to sacrifice some efficiency to get those advantages. On the other hand, today's high-quality LCDs can balance extreme efficiency with great picture quality. As with all technologies, improvements in HDTV performance are being made with every generation of products, and we expect power consumption to continue to fall in newer models.
From Practical Home Theater Guide
Power Requirements
Up to a year ago, this was one of those few issues in this plasma vs LCD TV analysis where LCD TV sets enjoyed a clear-cut advantage. However, the latest energy efficient plasma display panels from LG, Panasonic, and Samsung have significantly reduced the LCD power advantage. These new plasma panels consume some 40% less power than previous generations for the same brightness levels.
LCDs still have an advantage in this area; this arises out of the way LCDs use a backlight source to produce images. Backlighting of a display panel to produce an image requires less power than to light the individual cells in a plasma display.
Another major difference between plasma and LCD technology is that plasma displays require more power both with increase in pixel count - i.e. 1080p plasma displays use more power to operate than equivalent screen size 720p plasma sets, and also to display brighter objects. On the other hand, LCD panels generally require more power when handling large areas of dark subjects over a bright background. This in view that for an LCD display to present a dark subject, more pixels will have to be activated to block more of the light produced by the backlight source from reaching the display surface.
Actual power requirements in LCDs depend mainly on the technology used for the backlight. LCD panels using standard CCFL-based backlight systems require typically 30% less power than 1080p plasma displays of the same screen size; they also require some 20% less power than equivalent size 720p plasma displays. This difference in power requirements between the two display technologies becomes more pronounced as one moves towards the larger end of the scale, i.e. 55-inch and above. LCDs using LED backlights are even more energy efficient - with edge-lit LED TVs using less power than corresponding LED TVs using local dimming technology.
