Do flat-screen TVs eat more energy?

[TheHowling]

Television screens are getting bigger... and so are electricity bills

By Sean Coughlan
BBC News Magazine

Flat-screen TVs - a Christmas "must-have" in many households - are among the latest gadgets to be black-listed by environmentalists for their heavy power consumption. But are they really the 4x4s of home entertainment?

They're big and bright and flying off the shelves in the seasonal spending spree. Flat-screen televisions are accounting for eight out of 10 TVs bought this Christmas - casting their bulky old predecessors into the shade.

But while the cash tills might be ringing, there have been warnings about the environmental impact of this big-screen switch-over.

According to the government-funded Energy Saving Trust, plasma televisions which are 50% bigger than their cathode-ray tube equivalents "consume about four times more energy".

Gas guzzlers

In terms of carbon emissions, the EST says old-style TVs produce 100kg of climate-warming CO2 per year - while larger, plasma screens (there are no small plasma TVs) will pump out 400kg.


Flat-screen televisions are a big seller this Christmas

Supporting these claims, the EST points to research from the government-funded Market Transformation Programme, which advises the government on sustainability policy.

This says that, on average, the power consumption of a cathode-ray screen is 3.4 watts per screen inch, while plasma uses 9.4 watts per screen inch - based on figures from 2005.

So does that make these sleek new TVs the gas-guzzling 4x4s of home entertainment?

Not exactly. Flat-screen TVs broadly come in two varieties - plasma (which go from about 42ins to an almost cinematic 100ins-plus, and LCD, which are smaller, but, crucially, getting bigger all the time).

Power hungry

Peter Raynes, professor of opto-electronic engineering at the University of Oxford, says modern LCD screens use a similar amount of power to bulky old cathode ray tube (CRT) televisions.


Old-style televisions are on the way out

Plasma televisions are currently less efficient and will use more power, he says.

But Professor Raynes cautions about the difficulty in objectively comparing like with like - because there are unlikely to be any CRT televisions on the High Street which are the same size as plasma.

Manufacturer Philips, which makes CRT, LCD and plasma televisions, even rejects the broad assumption that plasma screens are inherently more power hungry - a spokesperson saying there was no clear, standardised, consensus on energy use.

And with rapid advances in technology, power consumption for all screens is set to become more efficient - rendering any current forecasts redundant.

Consumer power

But is this really about technology or about consumers hankering after bigger and bigger TVs?


The stand-by button can undermine any attempt at energy efficiency

The specifications from Philips' range shows how much it's the upscaling in size that matters - and also how difficult it is to generalise about power consumption.

Philips has won a European green television of the year award with its 42ins LCD television - which has a power consumption of 210 watts. In comparison, a 42ins plasma screen uses 230 watts. Not much different? Well, there's another plasma screen, the same size, same manufacturer, which uses 365 watts.

Then look at Philips' old-style televisions, where a medium-size 28ins widescreen only uses 87 watts and a portable 39 watts. And an LCD portable uses 42 watts.

And the 50ins plasma screen? A bumper-size 400 watts.

So you can be eco-conscious, buy the "green telly of the year", and still end up using twice as much energy as the old box you've thrown out. Confusing?

John Twidell, adviser on energy to the Institute of Physics, says consumers need to be given much more straightforward information about power consumption.

'Eco-mode'

Another key issue for energy consumption, says Dr Twidell, is turning off machines at the mains - and avoiding leaving televisions on stand-by. There's no point worrying about economising, if a television on stand-by is chewing up the power all day and night, every day.

There are other issues surrounding television energy consumption - such as the brightness of screens.

The Market Transformation Programme warns that televisions are often set for display in shops, rather than the much lower levels of light needed for home use.

It suggests that creating an "eco-mode" for screen brightness could cut power consumption by 15%.

And disposing of the unwanted CRT televisions is going to be a challenge in itself - with an anticipated 70 million old-style sets to be dumped by the end of the decade.

Once you've sorted out the power, there's still an even bigger question. Where do you put a 50ins flat-screen television in your living room?

[Bimbo]

Buy a projector, massive screen, low power (as long as you watch in the dark).

[TheHowling]

Originally Posted by Bimbo

Buy a projector, massive screen, low power (as long as you watch in the dark).

lol

some projector bulbs cost over £300.00 each and only last 3-4000 Hours

now thats gives a new meaning to time is money

[Idle_hands]

http://www.youtube.com/watch?v=ln8LjI5VXsY
Don't forget to add this video to TF Tube and see others there.

Wouldn't even cost that much to make one, im suprised you can crank HD resolution out on them things.
I did have the tutorial step by step page but I cant find it.

[meow]

The efficiency of light emiting devices is pretty disapointing,
High power leds are advertised as being very efficient but in fact theyr far far short of being any where near 100%.

flourescent is probably the best generaly available light source, this is used in flourescent bulbs and tubes (obviously) but also in the ordinary CRT tube type display for pc or tv. the principle is that a phospourescent material flouresces when it is exposed to high energy.

black and white is remarkably efficient, however colour requires effectivly three black and white systems with 2/3 of each one being wasted as it has to be filtered out.

I dont see why this 2/3 wastage could be reduced with some nift electronics but I guess tubes have gone out of fashion.

an alternative is the projector tv wich uses three indicidual black and white type tubes (well red blue and green but they are mono colour) and projects them onto a reflective screen, this is potentially quite efficient for a large screen, and doesnt suffer the same problems as rear projection tvs or lcd projector types.

plasma types also uses flourescent technology (I think) but as the devices have to be miniturised down to the size of one pixel the efficiency seems to slip away wich is disapointing as its probably the most promising otherwise.

another type of display is vaccum flourescent wich is similar to plasma but is highly efficient, you probably have one in you microwave oven, they are limited to size however and the density of pixels isnt that high, but very interesting shapes can be made for each pixel. they also have a vaccum in them wich makes a very large flat screen mechanicaly chalenging.

LCD is potentially very efficient indeed, but the problem here is that it doesnt actualy emit any light, so the backlight has to be on all the time even if al the pixels are off, also the large panels and electronics do consume more power themselves than smal ones (per sq inch). of course you could just put it in front of a window.

The differnt types of backlight offer different efficiency with EL (electro luminescence) being the highest but with quite short lifetime followed by cold cathode and led.

The most efficient form of light emiting device in small size is the laser diode, it is quite remarkable how efficient they are, however they are expensive and have limited lifetime, and limited in range of colours, although 1 laser can be shone onto a laser crystal to make it emit any colour of light, this makes for an interesting invention invented some time ago in rusia wich is a very small CRT with a laser crystal at the end instead of a phopshor, this makes the light output incredibly bright and (3 of them different colours) can be used for a very efficient projection system.