Wind for Power Has Big Hurdle: It
Doesn't Blow on Demand
Dec 28, 2006, International Herald Tribune
Wind, almost everybody's best hope for big supplies
of clean, affordable electricity, is turning out to
Engineeers have cut the price of electricity from
wind by about 8-percent in the last 20 years, setting
up this renewable technology for a major share of
the electricity market.
But for all its promise, wind also generates a big
problem: because it is unpredictable and often fails
to blow when electricity is most needed, wind is not
reliable enough to assure supplies for an electric
grid that must be prepared to deliver power to everybody
who wants it - even when it is in greatest demand.
In Texas, as in many other parts of the United States,
power companies are scrambling to build generating
stations to meet ever- higher peak demands, generally
driven by air conditioning for new homes and businesses.
But power plants that run on coal or gas have "to
be built along with every megawatt of wind capacity,"
said William Bojorquez, director of system planning
at the Electric Reliability Council of Texas. The
reason is that in Texas, and most of the United States,
the hottest days are usually the least windy. As a
result, wind turns out to be a good way to save fuel,
but not a good way to avoid building plants that burn
coal. A wind machine is a bit like a bicycle a commuter
keeps in the garage for sunny days. It saves gasoline,
but the commuter has to own a car anyway.
Xcel Energy which serves eight states from North
Dakota to Texas and says that it is the largest U.S.
retailer of wind energy, is eager to have more. Wind
is "abundant and popular," said Dick Kelly,
the chairman, president and chief executive, speaking
at a recent conference on renewable energy.
But Frank Prager, managing directyor of environmental
policy at Xcel, said that the higher the reliance
on wind, the more an electricity transmission grid
would need to keep conventional generators on standby
- generally low-efficiency plants that run on natural
gas and can be started and stopped quickly.
He said that in one of the states the company serves,
Colorado, planners calculate that if wind machines
reach 20 percent of total generating capacity, the
cost of standby generators would reach $8 per megawatt-hour
of wind. That is on top of a generating cost of $50
to $60 per megawatt-hour, after including a federal
tax credit of $18 per megawatt-hour.
By contrast, electricity from a new coal plant now
costs $33 to $41 per megawatt-hour, according to experts.
That price, however, would rise if the carbon dioxide
produced in buring coal were taxed, a distinct possibility
over the life of a new coal plant. Without major advances
in the ways of storing large quanitities of electricity
or big changes in the way regional power grids are
organized, wind may run up against its practical limits
sooner than expected.