Low Impact

External Power Supplies, also known as Plug Packs or more colloquially, “Wall-Warts”, are everywhere nowadays - they’re typically those bulky black plugs (pictured) that power your small appliances. Things like your cordless phone, or maybe your ADSL modem, or (almost certainly!) to charge your mobile phone. I’m guessing that most of us could easily find 5 of these things sitting around our houses.

Their purpose is to convert the high voltage AC current into the low voltage DC current that our smaller devices often need. Unfortunately, nothing is perfect and these little plugs aren’t necessarily that efficient.

It varies from power supply to power supply, but these devices are often only around 50% efficient. So half the electricity gets lost. How? Well, try touching the surface of one them - chances are it’ll feel warm. Thats the wasted electricity, being converted into heat.

To make things worse, some of these power supplies even consume electricity when they’re just sitting there unused. Lots of people leave their mobile phone’s plug in the wall and just connect the phone when it needs charging. Well, chances are that while the plug is sitting in the wall, it could be using around 1-2 watts without doing anything. It doesn’t sound like much, but that adds up to 13 Kw/H over a year, or up to 13 Kg of CO2 to do nothing!

There are hopeful signs on the horizon though - Nokia discusses the comparative efficiency of their chargers on their website and have a roadmap to improve their efficiency further by 2010. And the Australian Greenhouse Office is calling for public comment by 30 April 2007 on a proposal to mandate the energy performance of these power supplies. There is an excellent Regulatory Impact Statement on this website that gives a lot of the background on these power supplies, and some of the efficiencies of different makes and models. Its worth a quick read.

But while we’re waiting for all the manufacturers to get on board, just be aware of the issues. Keep in the back of your mind that the small appliance on the bench may in fact be using twice the power you thought, and if you’re not using a particular power supply, switch it off at the wall.

Categories: efficiency, environment, green, reduce