|
The instructor who would spend the next eight hours teaching
us about wind energy had each of us make a fist and imagine
a lump of coal about that size. Now consider 1,000 of those
lumps, he said, and you have about 1,000 pounds of coal—the
amount necessary to produce 1,000 kilowatt hours (kwh) of electricity
and the average amount of energy consumed by a 2,000 square-foot
residential Wisconsin home each month. (One kilowatt hour equals
the amount of electrical energy consumed when 1,000 watts are
used for one hour.) Each pound of coal burned, he added, releases
two pounds of carbon dioxide—a major greenhouse gas—into
the atmosphere.
For more than 20 years, Mick Sagrillo has worked as a wind
energy advocate, educator, and entrepreneur. In 1983, he founded
Michigan Wind & Sun, LTD, a company that makes wind generator
components and towers, refurbishes and repairs wind equipment,
and installs wind energy systems. He’s widely published
on the subject of wind technology and is a founding member
of the Midwest Renewable Energy Association.
In late February, Sagrillo came to Organic University, the
prequel to the Upper Midwest Organic Farming Conference in
La Crosse, Wisconsin, to show us how and why this clean and
renewable energy source makes sense on the farm.
Coal-generated electricity accounts for about 40 percent
all manmade carbon dioxide emissions released into the atmosphere.
And, although it represents less than 5 percent of the global
population, the United States is responsible for about 30
percent of all planetary greenhouse gas emissions. Consider
a country such as Denmark or Germany, where up to 70 percent
of electricity is wind generated, Sagrillo told us. Though
those countries are about half the size of Wisconsin, he said,
“There are 53 [electricity generating] windmills in
Wisconsin; there are more than 2,000 in Denmark. We’ve
got a long way to go in this country.”
Greenhouse gas emissions aren’t the only problem, Sagrillo
said; 50 percent of the mercury now polluting our lakes and
rendering fish toxic to eat rains down upon us from coal being
burned to make electricity.
Dollars and Sense
“Efficiency is not squandering resources,” Sagrillo
said as he explained the economic advantages of investing
up-front in energy saving devices such as compact fluorescent
light bulbs, good insulation and double-pane window. “Each
dollar spent on efficiency will save you $3 to $5 dollars
in system costs.”
So now that you’ve got your home super-insulated and
all your household and farm appliances are geared toward maximum
efficiency, it’s time to harness the power of the wind.
Basically, lift created by the movement of air turns a windmill’s
rotor blades—typically there are three of them—which
drive a generator, which produces electricity. “The
bigger the rotor, the more wind you can collect,” Sagrillo
explained. (And the more time-consuming and expensive to maintain,
he added.)
Sagrillo defined three basic categories of residential/farm
wind machinery. What he termed the “cabin” size,
a 1-kilowatt (kW) system with rotor blades about make this
8 to 11feet in diameter and the capacity to generate 30 to
100 kilowatt hours of electricity per month; “These
are relatively small machines…about 45 pounds,”
Sagrillo said. “You can literally throw them on your
back, climb up the tower and stick it up there.” The
“home” size, a 3kW to 6kW system with a rotor
blade diameter of 12 to 18 feet generating anywhere from 250-800
kwh of electricity monthly. And the “small farm”
size—10kW to 65kW systems with rotors spanning 22 feet
or more in diameter, and with the capacity to generate upwards
of 2,500 kwh of electricity per month.
According to a cost-estimate spreadsheet Sagrillo passed
out to the class, up-front costs for these larger systems—including
the tower and all installation costs—can range anywhere
from around $10,000 for a system that can generate around
100 kwh monthly, to just over $50,000 for a system capable
of generating 2,500 kwh monthly. (Key variables such as tower
height and average wind speed—which will be covered
in Part II of this series—will factor heavily in actual
performance.
The good news about these mid-sized systems is that there
is a growing supply of fully refurbished units to meet a growing
demand. “We’re just now seeing a redirection of
these types of turbines in places like California,”
Sagrillo said. “In California, [the utility companies]
are taking out the smaller turbines and putting in the behemoths…and
they’re finding a niche for this 20 year old equipment.”
That niche includes farmers and others.
“A school district in Spirit Lake, Iowa put up a 65kW
turbine and expected payback in seven or eight years,”
Sagrillo told us. “They paid for it in two years.”
These recycled units are being remanufactured and put back
on the streets with essentially the same warranty as new equipment,
Sagrillo said, adding that “there are reputable remanufactures
and disreputable ones—what we call Rustoleum rebuilds.”
Sagrillo counseled anyone considering a second-hand unit to
do their homework before making a purchase.
“A 65kW system, installed, will cost in the neighborhood
of $85,000 to $90,000; a machine like this will do 65,000
to 85,000 kwh a year, depending on where you’re at.”
Economies of
scale (and cooperation)
“As you go up in size, the cost of the electricity
that you generate goes down,” Sagrillo informs us.
Of course, the bigger the unit, the more complex; hence,
the increased maintenance investment. “Smaller units,
up to about 10kW, are direct drive,” Sagrillo said.
“Over 10kW, they are pretty much all gear driven.”
The next step up from a 65kW system is a doozie; about 10
times the size, at 660kW. Now we are talking 75-foot blades
on a 206-foot tower. And even this Brontosaurus of the windmill
world is becoming somewhat of a dinosaur for utility companies
because it is too small. The price tag on one of these units
installed as new equipment? Around $1.2 million.
Though a relatively new concept in North America, Sagrillo
said, cooperative purchase of such large-scale wind machinery
is commonplace elsewhere. “This is old hat in Denmark…less
than 10 percent [of the country’s 2,000 windmills] are
owned by utilities—they’re owned by the people.”
Sagrillo told us about a project near Toronto Ontario, Canada,
where a non-profit choreographed the purchase of one of these
huge machines and sold shares to local residents. “Over
the 20-year life of the turbine, [investors] get a check on
a regular basis; they’re getting back between 7- and
8-percent return on investment.”
The beauty of cooperative investment in wind energy, Sagrillo
said, is that you don’t necessarily have to have a windy
site to participate. “But we don’t do things like
co-ops very well in this country; the business model in this
country is everybody for themselves and everybody else be
damned. It’s not the best business model.”
Getting technical
Wind machines fall into two basic categories, Sagrillo said.
“Drag devices work by the wind literally blowing something
out of the way,” he said, giving the examples of those
quaint-looking water pumpers that are ubiquitous across the
rural landscape. The drag concept has been around for nearly
3,000 years and is not the most efficient use of wind power,
Sagrillo said. “These do an extremely good job of pumping
water; they do a lousy job of generating electricity.”
Lift devices work very much like, and resemble, airplane
wings, Sagrillo said. “Lift literally causes these blades
to be pulled forward similarly to the way that an airplane
is moved through the atmosphere. We’re basically taking
big chunks of moving air and we’re converting it to
rotational momentum to turn an electrical generator.”
Another way to visualize this concept, Sagrillo said, is
to imagine dense, high-pressure air molecules under the wing
or in front of the rotor blade displacing low-pressure, more
scattered molecules above the wing or behind the rotor blade,
thus creating lift.
Electricity is produced when coils of wire inside the generator
create a pulse as they move through a magnetic field, Sagrillo
said. The faster the turbines turn, he said, the faster the
pulse and the more electricity produced. Gear-driven turbines
enhance this efficiency, he said, because the generator spins
six to 18 times for every single revolution of the blades.
Smaller, direct-driven wind-energy systems typically have
a tail to keep them oriented toward the wind. These uncomplicated
systems are ideal for homeowners, Sagrillo said, because they
are easy to maintain and homeowners have a reputation for
letting things go. “They’re relatively simple
machines,” he said.
“A gearbox is a level of complexity that you add to
a turbine that a lot of people can’t deal with,”
Sagrillo said. But equipment maintenance is a reality of farming,
he said. “Every time you add a moving part, two things
happen. There’s a reduction in efficiency as energy
is dissipated in heat. And there’s considerable more
maintenance. The maintenance issue is why windfarm equipment
and industrial equipment is so different.”
Then there is dealing with the factor of too much wind.
“The blades on a direct-drive turbine are literally
bolted into place; the problem is that, at some point, the
wind is going to get too strong for this machine and we’ve
got to get rid of it,” Sagrillo said. “One of
the ways we can do this is by pitching the blades.”
Pitching the blades— turning them out of the wind’s
way—is accomplished through a few different methods,
Sagrillo said. In the most basic design, a tension spring
connecting the shaft of the blade to a central spider gives
way under a certain amount of force. “It’s simple,
reliable, and cost-effective.” More complex systems
utilize hydraulics and computers. This sophisticated design
is more typical of large-scale windfarm machinery, he said.
Rather than having a tail to guide them, these mammoth machines—which
are typically sited upwind—take their cues from a computer
linked to a 3-cup anemometer (to measure wind speed) and a
wind vane (to measure wind direction). “A motor moves
the blades around until they are facing back into the wind.”
 |
| Coming
up next: Two blades or three? Siting your windmill.
Selecting a tower.
|
|
“You can also pitch the entire rotor upwards or sideways,”
Sagrillo said, explaining that this is accomplished with the
aid of an offset pivot. (This is how smaller residential wind
equipment typically is protected from high winds.)
With all these incredible advances in clean energy technology,
why so many environment-choking coal-burning plants online
and planned for the future?
“Elecricity is the most frequently-bought product in
the United States; there’s nothing we consume more and
with more regularity than electricity.” That unfortunately,
Sagrillo said, means huge subsidies, gigantic campaign contributions,
and preserving the big-business status quo.
Dan Sullivan is senior editor at The New Farm. Mick Sagrillo
is owner of Sagrillo Power and light, a Wisconsin-based consulting
firm specializing in home-sized wind-turbine technology and
educational workshops.
|
