These days there are a lot of sources of energy for our lighting; coal, natural gas, wind, solar, and more. The good news is lighting is getting more efficient and consuming less energy; the bad news is more lighting is being added every day. The move from incandescent light bulbs to compact florescent light bulbs
is helping reduce energy use and greenhouse gas emissions, and LED lights will accelerate those savings in the not-too-distant future.
In 2005 Walmart started using LED freezer case lights. They found the LEDs use about 70 percent less energy, create much less heat (important in a freezer case) and last about as long as the cases do – saving money on both energy and maintenance costs. LED freezer lighting is now standard in all Walmart stores across the globe.
Freezer lighting is a niche application, but Walmart's next focus for LEDs is much more relevant to people in general – LED parking lot lights. If you live in the US, chances are you've seen parking lot lights, or even just street lights. Walmart first used LEDs in their parking lots in 2008 as a test. There they found the same benefits as with LED freezer lights – big energy and maintenance savings – in addition to some new benefits. The directional quality of LED light bulbs
means it's easier for a large scale installation to avoid light pollution by directing the light only to the parking lot ground.
They've converted 22 sites in Puerto Rico already, and are in the process of converting 350 stores in Central America. The biggest challenge is the initial investment, but with a massive company like Walmart it is more manageable. They have the capital to be able to wait years to recoup the costs of an LED retrofit. Years from now they will have made back all the money they spent while continuing to save huge amounts of money.