Computer Electricity Use

Peg heard a story on the radio about an elementary student who found that his family could save $1 per day by turning off the family’s computer at night. Not only did he get an A in this science project, but the school system realized that they could save a lot of money by turning off their 500 computers after school. This sounds a little fishy. Our LWVO survey finds that just abut all schools turn off things not in use. Also $1 per day electricity savings seem huge; this is the cost of about 10 kWh. If the turn-off is for 10 hours, their system uses about 1kW.

I decided to check. Here are the data from The Texas Office of Risk Management:

Computer -------------- ----------------------- 250 watts
Monitor ----------------- -----------------------150 watts
Speakers --------------------------------------- 15 watts
Electric stapler ---------------------------------- 25 watts
Scanner ---------------------------------------- 150 watts
HP Laser Jet 4 Printer (Idle) ------------------- 250 watts
(Printing) ---------------1,175 watts

Total 840 watts when idle
1,765 watts when printing

It appears that the student’s estimate may not be far off. However, $1/day = $30/month is almost our entire electric bill.

We don’t have an electric stapler and our scanner is off when not in use. Furthermore, we have an ink-jet printer, which takes mush less energy than a laser. I figure that our system uses maybe 400-450 watts for 16 hours per day or around 200 kWh per month. which is maybe half of our electric bill. Still a lot!!

Gasoline Usage

It was recently reported that Americans drove six billion fewer miles over a six-month period. There are 245 million motor vehicles in the US, of which 155 million are cars. If we consider both cars and trucks, the average mileage is about 17 mpg. So the average vehicle drove about 24 miles less over the six-month period and saved a little under 1-1/2 gal of gas.

Other statistics:

Americans used about 136 billion gallons of gas last year or about 550 gal/vehicle.
They also used about 7 billion gallons of ethanol.

The Big Energy Wasters

I'm very taken by a graph entitled 'U.S. Energy Energy Flow Trends - 2002' produced by Lawrence Livermore. It shows that about 85% of energy losses are due to electrical-generation/transmission and transportation.

Since electrical transmission is a small part of the loss, it's clear that the best thing we can do is to make power plants more efficient. And, if Wikipedia is to be believed, the technology is available to increase plant efficiency. If we only look at greenhouse gasses, we need more nuclear - no improvement in efficiency, but a big drop in emissions.

For transport, Congress passed a law increasing mileage on cars and Light-trucks/Vans/SUVs. According to the Energy Information Administration, car mileage has been trending upwardsfor about 30 years, while vans, etc. have plateaued since 1990. But big trucks have made no gains in mileage for 40 years. I find this hard to believe, so will check further.

Elevators

A little bit of encouragement that I gave to my colleagues:

You stand by the elevator and read the poster “Walk up one and walk down two for your health”. You will also save lots of electricity - elevators are energy hogs. Each one uses a much power as hundreds of light bulbs. So walk up one and walk down two and save energy.