July 24, 2007
Kamloops Daily News


Once we've turned the lights off and replaced old bulbs with
efficient new ones, then what?

Conservation can only achieve so much. Once all the
efficiencies have been applied, no further savings can be
reached.

There is a way to deliver more power to homes and businesses
without building any more plants or reducing energy
consumption.

I know it probably sounds too good to be true, something
like the promise of a natural gas salesman to save you money
by locking you into a long-term contract at inflated rates.
But this really works.

Conservation alone can't make up for the expected shortfall.
That's why the B.C. government hopes that private developers
will come with 2,500 gigawatt-hours of electrical energy in
the next three years.

I estimate that we can save that much power by making the
power lines more efficient. It involves a change in the way
power is carried.

This plan uses direct current instead alternating current.
Such a system has been in operation since 1992 between
Quebec and New England. It's especially efficient for long
power lines such as we have in B.C.

And the longer the lines, the greater the potential savings.
BC Hydro has 74,000 kilometers of transmission and
distribution lines. A lot of power is lost just hooking up
consumers to distant generators.

Conventional wisdom has sided with AC for the last century.
DC didn't have a chance in the "War of Currents" in the
1880s. George Westinghouse and the brilliant inventor
Nikola Tesla were on the side of AC. Thomas Edison and his
General Electric Company argued for DC and lost.

So why is DC more efficient now? Technology has made it
possible to transmit DC at high voltage, something that was
previously possible with AC only.

A century ago, transformers were the technology that won the
debate because they made it possible to send AC power at
high voltage. Inverters are the modern DC equivalent.

High voltage is the key because of the dual nature of power
which can be manifested as high voltage and low current or
the other way around. The high voltage/low current solution
is better because smaller conductors can be used.

Edison's loss was the consumer's gain. Power companies
switched to AC because of the ability of transformers to
step up AC voltage for transmission and then step it down
for distribution.

The AC transmission system has served us well for a century
but AC is starting to show its age. As the system grew, so
did problems with stability.

When girds are taxed to the limit, small outages can ripple
through the system as they did in 2003 when millions were
left without power in eastern Canada and the U.S.

Although both AC and DC can be converted to high voltage, AC
has some additional losses due to the nature of the current.

AC alternates in both magnitude and polarity. The problem
with changing magnitude is that the power lines have to
withstand the peak voltage even though the useable voltage
is less. These peak voltages cause losses that a constant
DC voltage doesn't.

Since the polarity changes, the current must charge and
discharge the line with each alternation. This current
contributes to additional loss.

DC systems are more efficient and more stable. Unlike AC
generators which must be precisely synchronized so that all
alternators are in lockstep, DC generators simply have to
match the line voltage before being connected to the grid.

Also, new technology allows for DC voltages to be converted
back into AC for greater flexibility. It's the same
technology that allows you to plug an inverter into your car
and get AC. This allows for DC transmission lines and AC
distribution systems can coexist as they do in the Quebec to
New England line. Because local distribution systems remain
unchanged, the DC line is transparent to the consumer.

Converting to DC is not cheap but neither is building new
generators. The advantage is that DC delivers more power
without burning fossil fuels in generators.

In addition, the investment in DC results in public
ownership unlike the government's proposal for private
generators. Construction of DC transmission lines results
in public ownership through the B.C. Transmission
Corporation. The B.C. government prefers that we pay for
private generators that we will never own.

Future generations will wonder why we didn't convert to DC
sooner.
 

David Charbonneau is the owner of Trio Technical.
He can be reached at dcharbonneau13@shaw.ca

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