Environmental Engineering Reference
In-Depth Information
capacity available for emergency shortages in New England fell below
the 15 percent safety margin in 2009 and will be below this safety margin
in the Midwest and mid-Atlantic regions by 2012, requiring some com-
bination of new power plants, more transmission lines, and electricity
conservation by consumers and business.
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Compounding the problem
is the fact that almost half of existing power plants are fueled by coal,
and these plants are increasingly criticized because coal is the most pol-
luting of the fossil fuels whose use dominates our energy supply.
About 79 percent of the nation's electricity transmission lines are
above ground, and 21 percent are buried. Burying power lines eliminates
potential problems such as icing of power lines in northern climates and
lines being knocked down by falling tree limbs on windy days. But buried
power lines are more susceptible to damage from fl oods and mudslides
and cannot necessarily be repaired quickly. The limiting factor for
burying power lines is the cost, which can be more than ten dollars a
foot. Burying existing overhead power lines costs ten to fi fteen times
more than the cost of stringing them from poles. The national trend in
cities is to bury lines when the city's infrastructure is being upgraded.
Now that billions from President Obama's 2009 stimulus package will
be going into upgrading infrastructure, the electric grids may become
smarter and more commonly underground.
The NERC says that the electric transmission system is being used
closer to its limits more of the time than in the past, and the demand for
power in summer is expected to increase by 18 percent by 2017. The
power blackout in the Northeast in 2003 was a harbinger of what the
future holds if remedial measures are not taken soon. About 2,000 miles of
high-voltage lines were built in 2006, a 1 percent increase in existing lines.
America operates about 157,000 miles of high-voltage (more than
230 kilovolts) electric transmission lines.
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Since 1982, growth in peak
demand for electricity—driven by population growth, bigger houses,
bigger televisions, more air conditioners, and more computers—has
exceeded transmission growth by almost 25 percent every year. Yet
annual investment in new transmission facilities has decreased by about
30 percent.
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The resulting increased grid congestion increases transmis-
sion and distribution losses, which have doubled to 10 percent since
1970. To correct defi ciencies in the existing system and enable the
smart power system of the future will require an additional $8 billion
to $10 billion annually. That additional investment will lead to an
average increase of 3 to 5 percent in consumers' electric bills. The
investment will pay for itself many times over by increasing the nation's
