Saturday, April 19, 2008

LCD vs. CRT vs. Trees vs. Michael Bay?

Anyone browsing craigslist recently would have probably noticed something in the technology section. There are tons and tons of free CRT monitors unable to find a home.

I don't know what the environmental harm this mass exodus of the mighty CRTs from our businesses and homes will be, but it'll probably be bad. In fact, one could figure out the 'environmental-return-on-investment' or EROI, by calculating some index of environmental harm, and comparing it to the environmental benefits of the power saving of LCD's.

It's funny to think that something that solves one problem, power-hungry CRTs burning up energy, creates another, CRT landfill, and that at some point in the future enough time will have passed such that the second problem will be exhausted (the damage from CRTs) while the benefits of the first will have aggregated over time. I for one do **not** volunteer.

However, what we can do is measure the power differences! Is it science? Who cares, it's fun! So I whipped out my Kill-o-Watt and did some measurements.

It turns out that, the way you use **both** changes the power usage. Here's the raw data:

- CRT Monitor -
All White Screen: 90 watts
All Black Screen: 71 watts
Average: 80.5 watts

- LCD Monitor -
All White Screen: 28 watts
All Black Screen: 29 watts
Average: 28.5 watts

- Some interesting numbers -
The CRT uses 27% more power displaying an all white vs. all black screen
The LCD uses 4% less power displaying an all white vs. all black screen
The LCD uses 35% less power, on average, overall of a CRT

It turns out that, as no surprise, a CRT monitor displaying nothing but black uses less power then when the screen is all white. This is because the gun firing at the screen is doing mostly nothing when drawing black. When the screen is white, the gun is firing all the time, in order to light up the whole screen, and so you get 20 more watts of power drain.

This is pretty interesting, since we usually don't think about **how** we use something as affecting the environment, especially when it comes to technology. If you have a CRT monitor, and a really bright and mostly white screensaver and desktop wallpaper, you're using up as much power and money, and doing as much damage as possible.

However, I didn't think that LCDs would register a noticeable difference, never mind the opposite effect! But it makes sense. With an LCD screen, the bulb inside is running all the time, regardless of what we are doing. However, the screen itself acts like a series of small, electronic sunglasses, turning on completely to block out all the light and create a black pixel, and turning off completely letting the light through and creating a white pixel.

It may only be 1 watt of difference, but it's interesting just the same. That means, if your screensaver, desktop wallpaper, and daily activities are black or mostly dark, then your maximizing the power, money and adverse environmental effects of your monitor.

But clearly, the LCDs use so much less power, you're still better off going LCD, for your power, money and environmental karma.

But here's what I really want to know:

What did Google's all white homepage cost the environment in carbon emissions back when CRTs were the common monitor?

What does Windows XP's default mostly black screensaver cost the environment in carbon emissions now that LCDs are the common monitor?

How many trees cry every time a Michael Bay movie explosion whites out a screen on a home theater system?