Environmental Engineering Reference
In-Depth Information
The Department of Energy has estimated that if every household in
the United States switched one of Edison's bulbs to a CFL, the country
would save enough energy to light 2.5 million homes and reduce green-
house gas emissions equal to 800,000 cars (0.3 percent of all the motor
vehicles on American roads). Another way to envision the saving from
CFLs is that replacing just one incandescent bulb with a CFL reduces
the need for 500 pounds of coal.
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Americans bought 21 million CFLs
in 2000, 100 million in 2005, and 400 million in 2007.
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There are 112
million households in the United States, so each household replaced more
than three incandescent bulbs on average. The U.S. Congress has set new
effi ciency standards that will make today's incandescent bulbs obsolete
by 2014.
CFL bulbs contain a small amount of mercury, much of which is
released if the bulb breaks. Open windows to dissipate the mercury
vapor. Then, wearing gloves, use sticky tape to pick up the small pieces
and powdery residue from the bulb's interior. Place the tape and pieces
of the bulb in a plastic bag. After vacuuming the area, place the vacuum
bag inside doubly sealed plastic bags before discarding. Unbroken bulbs
that have exceeded their lifespan should be recycled, not thrown into a
landfi ll where they may be broken.
The next advance in lighting will be light-emitting diodes (LEDs), light
generators that are twice as effi cient as CFLs and last twenty years.
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A
fl uorescent light bulb might last 3,000 hours while an LED fi xture lasts
more than 100,000 hours. The current downside to LEDs is their cost,
about $100, as opposed to $7 for a regular bulb, so it would take fi ve
to ten years to recoup the money in energy savings at today's electricity
prices. But the cost is decreasing rapidly, so the sticker shock will quickly
become less intimidating. Studies suggest that a complete conversion to
LEDs could decrease carbon dioxide emissions from electric power use
for lighting by up to 50 percent in twenty years. Some cities and expen-
sive hotels in the United States, as well as cities in China and Italy, and
Buckingham Palace in England have installed LEDs as replacements for
burned-out bulbs. Note that these municipalities and the palace do not
have the price constraints that individuals do. Cities can raise taxes,
hotels can increase their room prices, and the queen's budget is a bit
larger than yours or mine.
Dwelling Modifi cations
Many modifi cations to houses or apartments
will conserve energy and reduce both the use of fossil fuels and electric
bills. Perhaps the least costly is to place weatherstripping along the
