Dell has released some pretty jaw-dropping data this week about the energy-efficiency improvements that it has made to its product line over the past two years. Interestingly, the company also has expanded its efforts to offer recycling services for people looking to get rid of its old equipment.

Even though these two moves aren’t explicitly related, the proximity of these events has me wondering about the trade-off we are making when we swap old energy-sucking equipment for something new. The trade-off being, of course, that we have to dispose of that old technology somehow. Is it better to save energy or to send some nasty substance off to a landfill? Yes, I know that the U.S. public is a lot better informed these days about electronic waste, but I still feel as if it is a relevant question.

In any event, here is what Dell has to say for itself.

The energy efficiency of the Dell OptiPlex desktops improved by 50 percent from 2005 to 2008. Two specific configurations, the Dell OptiPlex 980 and the OptiPlex 780 have seen 48 percent reduction in the past two years, as well, when considered side-by-side with their similarly configured ancestors, the OptiPlex 960 and OptiPlex 760. Dell figures that since 2005, the energy savings associated with all of its OptiPlex sales during that time frame could be $5.2 billion, or 50 million tons of carbon dioxide emissions.

Dell has transitioned completely to LED displays for its entire laptop line. That’s good because they are mercury-free (fewer e-waste problems) and they use less energy compared with cold cathode fluorescent lamps (CCFLs). The company estimates that a 15-inch LED display, as an example, uses 43 percent less power at maximum brightness. That translates into potential savings of $20 million in energy for Dell customers using these LED displays over 2010 and 2011, according to some math that Dell has figured out.

Which leads us to the next part of the equation, what happens to the old stuff?

Dell has actually had technology recycling programs in place for quite some time, and it was the first computer manufacturer to adopt a policy that bans the export of non-working electronics. (That is important because these parts often enter an unauthorized electronic waste stream.) Dell reported this week that its Dell Reconnect initiative, as an example, has taken in about 170 million pounds of potential e-wasted since 2004, while creating about 250 jobs. The program, which is part of a partnership with Goodwill Industries International, now reaches more than 2,200 locations across North America. The latest locations (100 in all) are in Delaware, Massachusetts, Nebraska, Ohio, Pennsylvania and Rhode Island.

Clearly, these collection sites are targeted mainly at consumers and small businesses. Many larger companies are just starting to get on the ball with really formal hardware lifecycle management policies that consider the e-waste implications of old technology, not just the data destruction implications. I’m hoping that as the big tech firms keep improving their energy-efficiency they will likewise improve their procedures and partnerships for taking the cast-off equipment out of the electronic waste stream.