Wal-Mart Stores Inc. (WMT) is again making a charge into becoming an even greener eco-company than it already is. The world's largest retailer has stipulated that it wants to cut greenhouse gas emissions from its global supply chain by 2015. The example Walmart gave to illustrate the point: its reduction efforts would be like taking more than 3.8 million cars off the road for an entire year.

Wal-Mart Stores (NYSE: WMT) has made a pretty big PR push recently for all its "green" initiatives. From demanding smaller packaging containers to pushing eco-friendly light bulbs, the world's largest retailer wants to make sure that not only will it be a greener company, but that its customers will be greener too. Plus, it takes away from all the negative publicity Wal-Mart receives on so many fronts.

The company, regardless of motive, is doing things that really will be better for the sustainability of its locations, and also save the company money. One of the newer strategies features Wal-Mart's Canada division dimming store lighting by over 30% this summer. The retailer has a goal of reducing its carbon footprint by over 19,000 tons in 2007 -- this will help it get there.

Wal-Mart's Canada store count is 240, and the "dimming lights" project is expected to save an estimated 4,500 tons of carbon emissions over the course of the summer due to electricity savings that lead to less air pollution. It's interesting that Wal-Mart is not spinning this as a cost-savings measure but as a "saving-the-environment" measure -- and it's precisely what the retailer needs to do. Telling the world, consistently, that it's doing its part to reduce carbon emissions is a great leg on the good publicity show, which the retailer desperately needs.