This week, Home Depot fired a new marketing salvo in what is expected to be a broader national effort to get home customers to adopt LED lighting.

The Home Depot

The retail giant began selling some light bulbs in its highly energy-efficient lineup at a surprisingly affordable price of just under $20 online. Bricks-and-mortar stores will follow in September.

While $20 hardly sounds like a deal at first blush, such bulbs are expected to last as long as 30 years. Not long ago, such bulbs were not expected by most experts to cost less than $30 until 2012.

That’s the year, of course, when a federal law takes effect requiring that all bulbs sold in the United States be 30 percent more efficient than current incandescent bulbs. Even with improvements, incandescent bulbs are not expected to meet those standards, so many manufacturers are working on pushing their LED bulbs.

Unlike compact florescent bulbs, which have been unpopular with consumers because of the pallid light they cast, some newer LED bulbs are closer to the warmth and brightness of the regular incandescent. Home Depot says it is actively encouraging consumers to compare.

Home Depot is working with a Florida manufacturer, the Lighting Science Group, that also does contract work with National Aeronautics and Space Administration. Other manufacturers like the light bulb colossus General Electric have their own entrants in the affordable LED market.

A company spokeswoman said that the bulbs, which are sold under the EcoSmart label, are already so popular with consumers that they are having trouble keeping them in stock.