Taming the wind
for Michigan 2
Exelon Wind's first development
project, the Michigan Wind 2 farm, faced some high winds and rainy
weather during construction, but contractors and workers were still
able to complete the project by the end of 2011.
In an ironic twist, developers of the 90 megawatt Michigan Wind 2
project in the thumb region of the Midwest state had to contend with
too much wind during part of the project's construction.
The challenge arose during the fall of 2011 when the project developer,
Iowa-based Exelon Wind Corp., and its contractors were trying to erect
50 turbines near Minden City, Michigan.
"We had some struggles with excess moisture, but the bigger effects
were the wind days," said Doug Duimering, Exelon Wind regional manager
of business development. "So we had a lot of days when we were sitting
and waiting for lower wind days."
Nevertheless, Exelon Wind and its contractors met their goal of having
the wind farm completed and online by the end of 2011.
It's that strong wind that attracted Exelon Wind and its predecessor
company (John Deere Renewables) to the thumb region of Michigan in the
"There are some regions that stand out when you look at a wind resource
map, and the thumb region stands out as an excellent wind zone,"
The Michigan Public Service Commission has designated the thumb region
as "the area of this state likely to be most productive of wind
energy." The region is also predominantly agricultural, and a
transmission line runs through the thumb, all of which enhance its
attractiveness for wind development, Duimering said.
With the completion of Michigan Wind 2, Exelon Wind now has a total of
212 MW of wind-generated power in its Michigan portfolio. Including
Michigan, Exelon has 753 MW in its wind-generated portfolio spanning
eight states. Michigan Wind 2 also marks the first time that Exelon
Wind has developed a wind farm. (Exelon Wind is a division of Exelon
Corp. of Chicago.)
Michigan 2 is actually the second phase of the 69 MW Michigan Wind 1.
When Exelon Wind purchased John Deere Renewables LLC in September 2010,
it acquired both of the projects, as well as the 53 MW Harvest Wind I.
At the time, Harvest Wind I was under construction, and Michigan Wind 2
was in the very early stages of development. The Michigan Wind 1
project consists of 46 turbines in Huron County, northwest of the
Michigan Wind 2 project.
"Since we purchased Michigan Wind 2, we significantly expanded the
Michigan Wind 2 footprint and completed development work," Duimering
said. "We had an interconnection agreement for 90 MW, but we needed to
expand the footprint to support 90 MW."
As part of that initial development work, Exelon conducted
environmental studies on the impacts wind turbines would have on
migratory bats and birds, Duimering said. They showed the project would
not have a significant impact on the winged wildlife.
The studies also concluded that the turbines would not pose a risk to
populations of endangered species. In addition, noise studies showed
the low-frequency sounds produced by the turbines were similar to those
found in the area before wind farms were built, he said.
The turbines also were situated in ways to minimize sounds that might
be heard by nearby residents.
As part of its initial site work, Exelon Wind conducted an
investigation of the turbine options and determined that the V100-1.8
MW turbine from Danish manufacturer Vestas was the best fit, Duimering
said. The contract included delivery and commissioning, along with a
10-year service agreement.
"It has a relatively large rotor for its rated capacity," he said.
"From a productivity point of view, it produces a lot of megawatt hours
from this wind resource."
When completed, each turbine stands 145 meters—476 feet—to
the maximum tip height of the 100-meter blades.
Some of the land around the site was in pasture, but most was in
agricultural row crops. Other than building the construction and
maintenance roads to the turbine site, there was very little additional
site preparation, Duimering said.
The roads were built without gravel so most could be reclaimed back to
farmland after construction was complete.
Access roads were built for construction and reduced to 15-foot roads
at the end of the project, to provide future access for turbine
"Many of the farmers appreciate the site roads because it gives them
more off-site access to their farms than they had before," Duimering
The soil types in the area lend themselves to fairly standard turbine
Using standard equipment, workers excavated eight to ten feet deep for
the foundations. A cement foundation with a 65-foot diameter was then
poured for each of the 50 turbines.
Most of the turbine blades and parts, including the four-part towers,
were shipped via rail from Vestas' Colorado manufacturing facility to a
lay-yard near the center of the footprint.
They were then offloaded onto trucks for final transport.
"It had minimal impact on most of the regional transportation systems,"
Duimering says. "The main thing we trucked was the base of the tower.
There are four turbine segments, and the base was too big to put on a
rail car—not too heavy but too wide."
To accommodate the trucks, some of the local road intersections had to
be modified to allow the long trucks to navigate around the corners.
Once all of the components are delivered, installation goes pretty
quickly if the weather obliges, Duimering said.
"The main thing is getting the crane to the turbine site," he said.
"Once the crane is set up and you have suitable weather, you can stack
out the top segments of the tower and put on the blades and cell in one
to two days."
The Boldt Company of Appleton, Wisconsin, acted as the general
Construction started in late summer, and an unusually rainy fall posed
challenges to the installation. But it was the strong winds associated
with the storms—the more than unusually heavy rain—that
delayed installation at times.
Nevertheless, the workers completed the wind farm by Exelon Wind's goal
of December 31, 2011.
Wind in the Michigan thumb region is somewhat seasonal, Duimering said.
They can expect strong winds in the fall and winter, and therefore
greater generation, and weaker winds in the spring and summer.
S&C Electric Company of Chicago
engineered, designed, and constructed the Michigan Wind 2 Project.
S&C furnished and installed the 34.5-kV collector system for the
turbines, including the switching equipment and junction boxes, along
with 24 miles of cable. That aspect of the project was particularly
Although Exelon Wind's construction practice is to install cable in the
winter when it is less disruptive to farm production, most of the cable
needed to be installed in the spring, requiring special negotiation
with the farming community, said Dan Girard, S&C's director of
renewable energy and energy storage business development.
S&C also provided the 100-MVA interconnection substation that
delivers the energy collected from the wind plant, converting it from
34.5 kV to 120 kV. In addition, S&C
installed 12 miles of transmission line to tie the interconnection
substation to the existing Michigan Wind 1 Project 120-kV transmission
This too was tricky, Girard said.To minimize conflicts with the
community, the line needed to be situated in hedge rows and in areas
not already being farmed.
Recognizing that the intermittent nature of the wind can create voltage
stability problems on the transmission system to which a wind plant is
connected, early in the project, S&C conducted a study to determine
the need for VAR compensation at the Michigan Wind 2 Project. S&C
manufactures a fast-compensating reactive power source called the
PureWave DSTATCOM Distributed Static Compensator, which has been
applied at wind plants around the world to reduce voltage variations
and allow the plants to meet strict regulatory requirements.
"The study showed that a PureWave DSTATCOM isn't required for the
Michigan Wind 2 Project," Girard said. "The need for a compensation
system depends on a number of factors, including the location at which
the plant connects to the transmission system, and how it is connected."
Although it turned out that a VAR compensation system was not needed
for the Michigan Wind 2 Project, that isn't always the case, said Jim
Sember, S&C's vice president of power quality products. "As wind
farms are getting larger and there are more of them on the grid, we
expect systems like ours will be increasingly needed," he said. "About
25 to 30 percent of wind farms don't require a VAR compensating system.
Michigan Wind 2 is one such wind plan."
Under a Power Purchase Agreement, Consumers Energy of Jackson,
Michigan, has agreed to purchase the output from Michigan Wind 2 for 20
Exelon Wind is currently in the middle of constructing the Harvest Wind
II project, the second phase of the Harvest Wind I project.
The wind farm, consisting of 33 Vestas V-100 turbines near Pigeon,
Michigan, is expected to be completed this fall, Duimering said.
Exelon plans to expand its wind-generation portfolio through a
combination of in-house development and acquisitions of projects
developed by others that will be decided on a case-by-case basis, he