The problem is that the design of the standard incandescent bulb is hopelessly inefficient.
Electricity heats up the atoms in the filament, exciting electrons that release light. In the end, only 10 percent of the electricity that runs through the bulb actually generates light, with the rest used to heat the filament to more than 4,000 degrees.
In 2007, President George W. Bush signed the Energy Independence and Security Act, which annually increases efficiency requirements for light bulbs. By 2020, screw-in light bulbs will have to be 60 to 70 percent more efficient than today’s incandescent bulbs.
While the law doesn’t explicitly ban incandescent bulbs, they effectively have one foot in the grave. Manufacturers phased out old-style 100-watt incandescent bulbs as of Jan. 1; in many places only a few remain on retailers’ shelves. New types of incandescent bulbs comply with this year’s modest efficiency requirements, but it’s not clear that the design can ever meet the 2020 standards.
As we move away from standard incandescents, however, it’s not entirely clear what we’re moving toward. Several designs — including compact fluorescents (CFLs) and light-emitting diodes (LEDs) — meet the federal standards. So which of these is best for the environment?
The government has given you a little help in the form of a label. As of this year, bulb packages list lumens (how much light the bulb produces), watts (the power required to produce it), expected life span and a brief description of the light (from “warm” to “cool,” whatever that means).
If you were interested only in your personal energy bill, these labels do the job. But there’s much more to assessing a product’s environmental impact than counting up the kilowatt-hours it consumes while in use. It takes resources to mine the raw materials, assemble the product, transport it and dispose of it.
This was, in fact, the primary argument against compact fluorescent bulbs a few years ago. CFLs are the coiled tubular bulbs that you probably picture when you think of efficient bulbs. An electric current excites mercury and argon vapor inside the tubes, prompting the atoms to release ultraviolet light.
Critics of CFLs argued for years that, while the newfangled bulbs consumed less energy during use, their manufacture was so complex and exacting that they had a greater environmental impact over their lifetime than incandescent bulbs. (Virtually all new products marketed as environmentally friendly face this charge at some point, justifiably so in some cases more than others. Consider, for example, the preposterous Internet-sustained assertion that Hummers are actually better for the environment than hybrid-electric cars due to the energy required to manufacture hybrid batteries.)