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U.S. and Canada grids strained by high power demand

August 4, 2005

By Scott DiSavino

NEW YORK (Reuters) – Demand for electricity to power air
conditioners neared a record in New York on Thursday, but fell
short in other regional grids despite high heat and humidity.

The New York ISO, which operates the state grid for more
than 19 million New Yorkers, briefly climbed above its usage
record with demand at more than 32,100 megawatts by 3 p.m. EDT
(1900 GMT) on Thursday, but it did not count as an official
record because it was not sustained for at least an hour.

A spokeswoman at the New York ISO, Carol Murphy, said power
demand officially peaked at 32,026 MW between 2 p.m. and 3
p.m., just shy of the record 32,075 MW set on July 26.

“Some weather came through and clipped the peaks,” Murphy
said.

PJM, which operates the biggest U.S. power grid for more
than 51 million people in parts of 13 Mid-Atlantic and Midwest
states, had forecast record-breaking demand on Thursday, but a
spokesman said storms that developed in the East cooled things
off.

“It turns out we peaked for the day at 133,205 megawatts,”
said PJM spokesman Ray Dotter, noting demand fell well short of
the grid’s all-time high of 135,000 MW hit on July 26.

PJM and some utility members asked Mid-Atlantic region
consumers to conserve electricity on Thursday to avoid
straining the system.

The Midwest ISO, which operates the power grid for more
than 36 million people in 15 states and the Canadian province
of Manitoba, set a new usage record on Wednesday when demand
reached 131,434 megawatts, topping Tuesday’s record of 131,188
MW.

The Midwest ISO did not expect to break the record again on
Thursday since the weather has cooled over the western part of
its huge territory.

One MW powers about 800 homes, according to the North
American average.

High temperatures from Toronto to New York City again
climbed into 90s Fahrenheit on Thursday, with the humidity
making it feel like more than 100 degrees.

ONTARIO SYSTEM STRAINED

The Ontario power system has been under more strain this
week than the U.S. grids.

On both Wednesday and Thursday, the Independent Electricity
System Operator, which operates the province’s grid used by
more than 11 million people, activated a 5 percent voltage
reduction, which reduces the flow of power on the lines.

But by 5 p.m. EDT, a spokeswoman for the IESO, Lisa
Pearson, said that the voltage reduction had been lifted and
voltage levels had returned to normal.

She said loads were starting to lighten, and demand
Thursday did not come near breaking a record.

In addition to high demand this week, the province had
outages affecting about 3,000 MW of generating capacity.
Limitations on transmission lines connecting Ontario to
neighbors in the United States and Canada hampered imports.

Although the current heat wave will start to break in the
Midwest late Thursday, bringing needed relief to Ontario, PJM
and the New York ISO must keep watching power flows as the
Atlantic Coast will not start to cool until Friday night.




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