There it is, midway between the wall outlet and my laptop: the power brick. Two inches wide, five inches long and an inch tall, it’s the AC power adapter, putting my household power supply in a form my computer can use.

The U.S. Department of Energy says there are some 300 million of these “external power supplies” shipped in the U.S. every year, which is what makes new efficiency standards for them so important: The DOE says toughening up standards that were last updated in 2007 will “help cut carbon pollution by nearly 47 million metric tons – equivalent to the annual electricity use of 6.5 million homes – and save families and businesses nearly $4 billion on their energy bills.”

energy efficiency power adapter
image via Amazon

In a blog post, the National Resources Defense Council’s Pierre Delforge explained that the new standards will help by taking aim at a couple of ways that external power supplies (ESPs) consumer energy. He writes:

  • In “No Load” when the EPS is plugged in but the device is disconnected, for example when you disconnect your phone from its adapter but leave the adapter plugged into the wall.  In this mode, the EPS draws a small amount of current over a long period of time (often 24/7), which adds up.
  • In active mode, where the power conversion process wastes anywhere between 10 to 50 percent of the power drawn by the device while in active use. There were 345 million new EPSs sold in the US in 2009, and there are probably well over 1 billion in use today throughout the country! While most consume a modest amount of energy individually, they add up and in aggregate are responsible for several power plants worth of electricity consumption.

It’s not only external power supplies that have been the focus of DOE’s attention. Last week, the department announced new efficiency standards for metal halide lamp fixtures, which you see lighting big spaces – athletic fields, parking lots, big-box stores, that kind of thing. Savings from the consumer savings from the new standards are pegged at “more than $1.1 billion on their energy bills” over the next 30 years.

Now, all this said, there are some who warn that energy efficiency‘s benefits can be overstated. Among other things, they cite the cost of implementing new standards and the “rebound effect,” wherein improved efficiency — and thus cheaper operating cost — induces greater use, canceling out at least some of the gains. The Breakthrough Institute makes the case for caution on energy efficiency assumptions here; meanwhile, the NRDC makes the case for a full-fledged commitment to energy efficiency here.

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