Your Company


With 105.6 MW of generating capacity, MidAmerican Energy Co.’s Vienna wind farm, located in Iowa’s Marshall and Tama Counties, is relatively small compared with the utility company’s 12 other Iowa-based wind projects.

However, although it may be dwarfed by the 443.9 MW Rolling Hills or 286.4 MW Pomeroy wind farms, the Vienna project is an important contributor among MidAmerican’s wind empire.

Des Moines-based MidAmerican Energy provides service to customers in a 10,600-square-mile area in Iowa, Illinois, South Dakota and Nebraska and is the No. 1 owner of wind-powered electric generation among rate-regulated utilities. MidAmerican Energy, a subsidiary of MidAmerican Energy Holdings Co., had slightly more than 8 GW of owned and contracted generating capacity by the end of 2012, with approximately 30% coming from wind generation.

Completed in November 2012, the Vienna wind farm is powered by 45 Siemens wind turbines with a rated capacity of 2.346 MW – slightly more than Siemens’ workhorse 2.3 MW turbine. Siemens increased the rated capacity of the turbine based on a MidAmerican request, and the details behind the upgrade are confidential; however, MidAmerican says the request required Siemens to make “software and other modifications.”

With capacity factors ranging “north of 38 percent,” the Vienna wind farm packs quite a punch. According to MidAmerican, the project ranks near the top of its Iowa wind farms when it comes to capacity factor and fourth in energy produced per turbine.

“[Vienna] is one of the smaller parks in our portfolio, but it has the newest technology, which contributes to its higher output,” explains Adam Wright, MidAmerican’s vice president of wind generation and development.



The wind farm was originally developed by West Des Moines, Iowa-based RPM Access, which later sold it to MidAmerican in 2011. Minneapolis-based M.A. Mortenson was the engineering, procurement and construction contractor for the site and was instrumental in helping complete the project in time to qualify for the Dec. 31, 2012, production tax credit (PTC) deadline.

Thanks to a well-planned campaign, the Vienna wind farm was completed around Thanksgiving –about seven weeks ahead of schedule, Wright says.

While “nothing insurmountable” occurred during construction, he notes that the project was plagued by both extremely high temperatures and high-wind conditions. In fact, Wright says that the blustery conditions during construction were some of the strongest in recent memory.

“At the time of construction, there was a drought,” he recalls. “It was hot and windy. Normally, you don’t get both conditions at a site.”

As a work-around, project leaders determined it best to perform construction and turbine-erection activities in the cooler evening and overnight hours.


“The project experienced a challenging wind routine that moved critical activities [such as turbine erection] to a night shift,” explains Tom Kristensen, construction executive at Mortenson. “That year faced the PTC deadline, so construction had to take advantage of any window, regardless of the time.”

Also, understanding the full weight of the deadline, Wright and the entire Vienna project team were in constant communication. “[Coordination] is a critical part of the process. You want to make sure you have enough resources,” Wright says. “We worked hard to get out in front of issues.”

He credits turbine supplier Siemens, whose blades and nacelles were manufactured at facilities in Fort Madison, about 200 miles from the project site, for assistance in turbine commissioning.

No stranger to MidAmerican, Siemens supplied SWT-2.3-108 turbines for the utility’s 200.1 MW Eclipse project and 101.2 MW Morning Light wind farm. Additionally, Siemens is providing a five-year service, maintenance and warranty agreement.

Recently, MidAmerican received the go-ahead from the Iowa Utilities Board on plans to build an additional 1,050 MW of installed capacity. If the full 1,050 MW are constructed, MidAmerican Energy will own and operate approximately 3.3 GW of wind generation capacity in Iowa by the end of 2015.

While it is unclear whether Siemens and MidAmerican will again partner on its latest Iowa expansion, one thing is certain: MidAmerican sees several advantages in wind ownership.

“Wind facility ownership can provide the potential for customer benefits associated with economies of scale, the ability to optimize site selection flexibility and ownership, the leveraging of vendor contracts through the competitive bid process, as well as the development of long-term operational expertise,” says Wright.

Another advantage, according to Wright, is controlling the maintenance schedule.

Because it has 13 wind farms in its portfolio, MidAmerican can coordinate schedules to limit the amount of downtime, as well as amortize the costs across its entire fleet.

“Project ownership allows for effective maintenance planning and cost control for the life of a project, which can provide improved availability while controlling costs,” Wright explains. w

Project Profile: Vienna

Don’t Be Deceived By Size: Vienna Project Packs A Punch

By Mark Del Franco

Though relatively small by MidAmerican’s standards, the 105.6 MW Vienna project is an important contributor for the rate-regulated utility.





NAW_body hyperlink NAW_body_i NAW_body_bi NAW_body_b_i NAW_body_b








NAW_SH norule