June 16, 2010
How Many Energy-Efficient Light Bulbs Does It
Take to Close 705 Coal Plants?
Lester R. Brown
The lighting sector is on the edge of a spectacular revolution, a
shift from the century-old, inefficient incandescent light bulb to
far more efficient technologies. Perhaps the quickest, most
profitable way to reduce electricity use worldwide—thus cutting
carbon emissions—is simply to change light bulbs.
The first advance in this field came with compact fluorescent
lamps (CFLs). Replacing old-fashioned inefficient incandescent bulbs
that are still widely used today with new CFLs can reduce the
electricity used for lighting by three fourths. Over its lifetime,
each standard (13 watt) CFL will reduce electricity bills by roughly
$30. And though a CFL may cost twice as much as an incandescent, it
lasts 10 times as long. Each one reduces energy use compared with an
incandescent by the equivalent of 200 pounds of coal over its
lifetime. For perspective, the energy saved by replacing a 100-watt
incandescent bulb with an equivalent CFL over its lifetime is
sufficient to drive a Toyota Prius hybrid car from New York to San
Francisco.
CFL production in China, which accounts for 85 percent of the world
total, climbed from 750 million units in 2001 to 3 billion units in
2007. Sales in the United States climbed from 21 million CFLs in
2000 to 397 million in 2007. Of the estimated 4.7 billion light
sockets in the United States, close to 1 billion now have CFLs.
The world may be moving toward a political tipping point to replace
inefficient light bulbs across the board. In February 2007,
Australia announced it would phase out the sale of incandescents by
2010, replacing them with CFLs. Canada soon followed with a 2012
phaseout goal. In early 2009, the European Union (EU) approved a
phaseout of incandescent bulbs, one that will save the average EU
consumer 25–50 euros each year.
Brazil, hit by a nationwide electricity shortage in 2000–02,
responded with an ambitious program to replace incandescents with
CFLs. As a result, an estimated half of the light sockets there now
contain these efficient bulbs. In 2007, China—working with the
Global Environment Facility—announced a plan to replace all its
incandescents with more-efficient lighting within a decade.
Retailers are joining the switch too. Wal-Mart, the world’s largest
retailer, began an ambitious marketing campaign in 2007 to boost its
cumulative U.S. sales of compact fluorescents to over 260 million.
Currys, Britain’s largest electrical retail chain, went
further—discontinuing sales of incandescent light bulbs in 2007.
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CFLs contain a small amount of mercury (about one fifth the
quantity in a watch battery), but they can be safely
recycled at the end of their useful lives. Burning the coal
needed to power one incandescent light bulb releases much more
mercury into the atmosphere—and eventually the water and food
supply—than the amount contained in a CFL.
For office buildings, commercial outlets, and factories, where
linear (tubular) fluorescents are widely used, the key to cutting
electricity use is shifting to the most advanced models, which are
even more efficient than CFLs. The potential savings are large;
since linear fluorescents are long-lasting, many of those now in use
rely on an earlier, less energy-efficient technology.
The second major advance in lighting technology is the
light-emitting diode (LED), which uses up to 85 percent less
electricity than an incandescent bulb. Although LEDs are the
ultimate in lighting efficiency, they are still too costly for most
uses. They are rapidly taking over several niche markets, however,
such as traffic lights, where they now have 52 percent of the U.S.
market, and exit signs in buildings, where they hold 88 percent of
U.S. sales. New York City has replaced traditional bulbs with LEDs
in many of its traffic lights, cutting its annual bill for
maintenance and electricity by $6 million. In early 2009, Los
Angeles Mayor Antonio Villaraigosa said the city would replace its
140,000 street lights with LEDs, saving taxpayers $48 million over
the next seven years. The resulting reduction in carbon emissions
would be like taking 7,000 cars off the road.
Universities are also getting involved. In California, the
University of California-Davis has a Smart Lighting Initiative. One
of its first projects was to replace all the light bulbs in a campus
parking garage with LEDs, dramatically reducing electricity use.
This success has evolved into LED University, a project to
disseminate this technology. Early adopters include the University
of California-Santa Barbara, Tianjin Polytechnic University in
China, and the University of Arkansas.
LEDs offer another strong economic advantage. While CFLs last 10
times as long as incandescents, LEDs last 50 times as long. Indeed,
a typical LED installed at the time of a child’s birth will still be
working when the youngster graduates from college. The savings in
commercial situations from both lower electricity costs and the
virtual elimination of replacement maintenance often more than
offsets the higher initial cost.
In addition to switching bulbs, energy can be saved just by turning
lights off when they are not in use. There are numerous technologies
for doing this, including motion sensors that turn lights off in
unoccupied offices, living rooms, washrooms, hallways, and
stairwells. Sensors and dimmers can also be used to take advantage
of daylighting to reduce the intensity of interior lighting when
sunlight is bright. In cities, dimmers can be used to reduce
streetlight intensity. In fact, these smart lighting technologies
can cut the electricity use of LEDs to less than 10 percent that of
incandescents.
In summary, shifting to CFLs in homes, to the most advanced linear
fluorescents in office buildings, commercial outlets, and factories,
and to LEDs in traffic lights would cut the world share of
electricity used for lighting from 19 percent to 7 percent. This
would save enough electricity to close 705 of the world’s 2,670
coal-fired plants. (See
data.) If the high cost of LEDs drops faster than we have
assumed, making widespread use feasible, lighting efficiency gains
will come even faster than we have projected.
In a world facing almost daily new evidence of climate change and
its consequences, a quick and decisive victory is needed in the
battle to cut carbon emissions and stabilize climate. A rapid shift
to the most energy-efficient lighting technologies would provide
just such a victory—generating momentum for even greater advances in
climate stabilization.
Adapted from Chapter 4, “Stabilizing Climate: An Energy Efficiency
Revolution” in Lester R. Brown,
Plan B 4.0: Mobilizing to Save Civilization (New York:
W.W. Norton & Company, 2009), available on-line at
www.earthpolicy.org/index.php?/books/pb4