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Engineers use computers to track what’s going
on with the region in this control room for grid operator PJM in Valley Forge,
Pa.
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High-voltage electric lines are part of the
giant network that makes up the electric grid.
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Round-the-clock work
keeps the giant network going so the lights stay on
By Kathiann
Kowalski
Flip a switch at
home, and a light or gadget comes on. In most cases, the electricity to power
that device came from a huge system called the electric grid. Here’s how it
works.
Maybe you’ve built an
electric circuit with a battery and a light bulb. Current flows from the
battery through wire to the light bulb. From there it flows through more wire
and back to the battery.
You also can set up
the wires to connect multiple light bulbs so some can be on even if others are
off. The electric grid uses a similar idea, but it’s more complex. A lot more.
Electricity gets made
at lots of places: Power plants that burn oil, gas or coal. Nuclear plants.
Solar panel arrays. Wind farms. Dams or falls over which water cascades. And
more.
In most places, the
grid connects hundreds or more of these places to a vast network of wires and
equipment.
Electric current can
travel along many paths within the network. Power also can flow either way
along wires. Equipment tells the current where to go.
Two-way wires also
allow the use of alternating current, or AC. Electric grids in most countries
use AC current.
AC means the current
switches direction many times per second. With AC, equipment called
transformers can change the voltage, or force of the current.
High voltage is more
efficient for sending electricity over long distances through wires. Other
transformers then step the voltage down to lower, safer levels before the
current travels on to homes and businesses.
A balancing act
The electric grid is
so big and complex that it needs whole buildings full of people and machines to
control it. Those groups are called grid operators.
A grid operator is a
bit like a high-tech traffic cop. It makes sure power goes from electricity
producers (known as generators) to where people will need it.
The United States’
lower 48 states have 66 of these traffic cops. They work in three major
regions. The largest span parts of more than a dozen states! Local electric
companies do a similar job in their areas.
There’s
a catch. “We need to keep things perfectly balanced,” explains
electrical engineer Chris Pilong.
He works at PJM
Interconnection in Audubon, Penn. PJM runs the grid for all or parts of 13
states, plus the District of Columbia.
By balanced, Pilong
means that the amount of electricity supplied at any time must match the amount
used.
Too much power could
overheat wires or damage equipment. Too little power can lead to problems such
as blackouts and brownouts.
Blackouts are losses
of all power to some region. Brownouts are partial drops in the system’s
ability to supply power.
Computers help
engineers get the match right.
Meters, gauges and
sensors constantly monitor how much electricity people are using. Computer
programs also use data about electricity use during periods in the past when
the hour, day and weather were similar.
All that information
helps the grid’s traffic cops figure out how much electricity needs to go on
the grid to meet people’s needs.
Grid operators make
those forecasts from minute to minute, hour to hour and day to day.
Grid operators then
tell producers how much more power — or less — to supply. Some big customers
also agree to cut back their energy use when needed.
The system isn’t
perfect and things do go wrong. Indeed, grid operators expect problems will
develop now and again.
“It’s
a normal occurrence,”
says Ken Seiler, who heads up system planning at PJM. “But it’s more the
exception than the rule.”
If one power plant
suddenly stops putting its power onto the grid, others are usually on standby.
They’re ready to supply electricity as soon as the grid operator gives the
go-ahead.
Most power outages
actually take place at the local level. Squirrels chew through wires. A storm
brings down power lines.
Equipment somewhere
overheats and catches on fire. But extra trouble can pop up when extreme
weather or other emergencies happen.
Hurricanes, floods,
tornadoes and other events can all bring down parts of the system. Droughts and
heat waves can spike the use of air conditioners — big energy hogs!
Different kinds of
extreme weather will become more frequent as climate change intensifies.
The risk of physical
or cyber-attacks presents additional threats. Even space weather can make
problems flare up on the grid.
Beyond all this, many
parts of the power-grid system are more than 50 years old. They can just break
down.
Looking ahead
Scientists and
engineers are working to prevent problems. But when problems do occur, they
want to get the lights back on as soon as possible.
Engineers also are
working to adapt the grid to a changing electricity supply.
Natural-gas prices
have fallen because of a recent boom in gas production in the United States and
other countries.
As a result, older
coal and nuclear plants have trouble competing with the low-cost power
generated in plants that run on natural gas.
Meanwhile, more wind
power, solar energy and other renewable resources are joining the mix. Prices
for these clean-energy alternatives have fallen a lot in recent years.
Battery storage also
will let renewable energy play a bigger role. Batteries can store extra
electricity from solar panels or wind farms.
Then the energy can
be used regardless of the time of day or the weather at the moment.
At the same time, the
grid will rely even more on computers so that many systems can “talk” to each
other.
More advanced
equipment will go onto the system too. Some “smart switches” will get the
lights back on more quickly when there’s a problem.
Others can more
nimbly steer electricity onto the grid from renewable energy sources.
Meanwhile, sensors and other devices will pinpoint problems, boost efficiency
and more.
Many customers want
more data as well. Some want to see their energy use detailed in 15-minute
chunks. That can help them focus their energy-saving efforts.
Many people also want
to pay more or less based on the time of day that they actually use
electricity.
“Smart grid”
initiatives aim to deal with all those issues.
Research continues at
universities and other research centers. Ideally, all of this work can make the
grid more reliable and resilient.
Kathiann
Kowalski
loves talking with scientists and engineers about their work and why it
matters. And she loves getting into the field — whether that’s at a lab, in a
research forest, at a drilling site or on a research boat. She has written more
than 700 articles, plus 25 books for young people. “There’s always something
new happening — and something new to learn,” she says.
Kathi
graduated from Hofstra University in New York and got her law degree from
Harvard Law School in Massachusetts. She previously practiced environmental law
with a large firm. Kathi enjoys hiking, sewing, reading and travel.
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