Wind Energy Issues [RE-wrenches]

[Dana Orzel]

This was sent by a client. It is interesting collection of information.

 

Dana Orzel

Great Solar Works, Inc.

"Responsible Systems For Responsible People"

dana at solarwork.com

970.626.5253 - H/O

970.209.4076 - C

970.626.4140 - F

 

December 28, 2006
The Energy Challenge
It's Free, Plentiful and Fickle 
By MATTHEW L. WALD
Wind, almost everybody's best hope for big supplies of clean, affordable
electricity, is turning out to have complications.
Engineers have cut the price of electricity derived from wind by about 80
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 country, power companies are
scrambling to build generating stations to meet growing peak demands,
generally driven by air-conditioning for new homes and businesses. But power
plants that run on coal or gas must "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 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 that 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
it is the nation's largest retailer of wind energy, is eager to have more.
Wind is "abundant and popular," said Richard C. Kelly, the chairman,
president and chief executive, speaking at a recent conference on renewable
energy. 
But Frank P. Prager, managing director of environmental policy at the
company, 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 will reach $8 a megawatt-hour of
wind. That is on top of a generating cost of $50 or $60 a megawatt-hour,
after including a federal tax credit of $18 a megawatt-hour.
By contrast, electricity from a new coal plant currently costs in the range
of $33 to $41 a megawatt-hour, according to experts. That price, however,
would rise if the carbon dioxide produced in burning coal were taxed, a
distinct possibility over the life of a new coal plant. (A megawatt-hour is
the amount of power that a large hospital or a Super Wal-Mart would use in
an hour.)
Without major advances in ways to store large quantities of electricity or
big changes in the way regional power grids are organized, wind may run up
against its practical limits sooner than expected.
At a recent discussion of clean energy technologies held at General
Electric's research center in Niskayuna, N.Y, Dan W. Reicher, a former
assistant secretary of energy for conservation and renewable energy,
predicted that renewables, led by wind, could reach 20 percent of demand in
the next decade or two. President Bush has also said that wind could supply
20 percent of the nation's electricity. 
But Mr. Reicher drew a quick response from James E. Rogers, chief executive
of Cinergy, one of the nation's largest utilities, and chairman of the
Edison Electric Institute, the industry's trade association. "I love his
optimism," Mr. Rogers said. "But unfortunately, I have to deliver
electricity every day." 
Mr. Rogers said that wind and another big renewable source that is available
only when nature cooperates, solar power, will be necessary because the
government would eventually regulate carbon emissions from coal-fired power
plants. He later said that his reply to Mr. Reicher had been a "cheap shot,"
but he and others are still wondering how much wind the nation can absorb. 
General Electric, a major maker of wind machines, says that along with
lowering the price for a megawatt-hour, engineers have made other
improvements in wind machines. With better electronic controls, many of them
now help stabilize voltage on the grid, and have been cured of their
tendency to shut off when detecting a voltage fluctuation, a problem that
can escalate into a blackout. 
Juan de Bedout, manager of the electric power and propulsion systems lab at
G.E., said this was more important now because wind machines had grown from
a few hundred kilowatts to 1.5 gigawatts, and his company was exploring
machines four times bigger than that. "That's ginormous," he said.
In many places, wind tends to blow best on winter nights, when demand is
low. When it is available, power from wind always displaces the most
expensive power plant in use at that moment. If wind blew in summer, it
would displace expensive natural gas. But in periods of low demand, it is
displacing cheap coal.
And in places where suppliers enter bids each day to supply power on the
next day, on an hour-by-hour basis, wind is at a disadvantage. Wider use of
wind requires the invention of a new kind of weather forecasting, according
to the Electric Power Research Institute, a nonprofit consortium based in
Palo Alto, Calif., sponsored by the utility industry and its suppliers.
Rather than forecasting from temperature or rainfall, what is needed is a
focus on almost minute-by-minute predictions of wind in small areas where
the turbines are.
The economics of wind would change radically if the carbon dioxide emitted
by coal were assigned a cash value, but in the United States it has none.
Coal plants produce about a ton of carbon dioxide each megawatt hour, on
average, so a price of $10 a ton would have a major impact on utility
economics. 
Another possibility is energy storage, although this presents other
difficulties. 
In May, Xcel and the Energy Department announced a research program to use
surplus, off-peak electricity from wind to split water molecules into
hydrogen and oxygen. The hydrogen could be burned or run through a fuel cell
to make electricity when it was needed most. Xcel plans to invest $1.25
million, and the government $750,000. But storage imposes a high cost: about
half the energy put into the system is lost. 
The Electric Power Research Institute said that existing hydroelectric dams
could be used as storage; they can increase and decrease their generation
quickly, and each watt generated in a wind machine means water need not be
run through the dam's turbines; it can be kept in storage, ready for use
later, when it is most needed.
The institute listed another possibility, still in the exploratory stage:
using surplus electricity made from wind to pump air, under pressure, into
underground caverns. At peak hours, the compressed air could be withdrawn
and injected into generators fired by natural gas. Natural-gas turbines
usually compress their own air; compression from wind would cut gas
consumption by 40 percent, the institute said. 
That would help with an important goal, reducing consumption of natural gas,
which is increasingly scarce and costly in North America. But not everyone
is so sanguine that wind will do that.
Paul Wilkinson, vice president for policy analysis at the American Gas
Association, the trade group for the utilities that deliver natural gas,
said that wind, while helpful in making more gas available for home heating
and industrial use, would still need a gas generator to back it up. And the
units used as backup are generally chosen for low purchase price, not
efficient use of fuel. 
At the American Wind Energy Association, Robert E. Gramlich, the policy
director, said that one solution would be to organize control of the
electric grid into bigger geographic areas, so that a drop-off in wind in
one place would be balanced by an increase somewhere else, reducing the need
for conventional backup. That is among several changes the wind industry
would like in the electric system; another is easier construction of new
power lines, because many of the best wind sites are in prairies or mountain
ranges far from where the electricity is needed. 
A problem for new power lines is that they would be fully loaded for only
some of the year, since the amount of energy that the average wind turbine
produces over 12 months is equal to just 30 to 40 percent of the amount that
would result from year-round operation at capacity. That number runs closer
to 90 percent at a nuclear or coal plant. 
Thus a 1,000-megawatt nuclear plant will produce nearly three times as much
electricity as 1,000 megawatts of wind turbines. But operating costs at the
wind farm are lower, and the fuel is, of course, free.


 


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