Harvesting The Wind

Sept. 28, 2010

Airtricity North America, Inc. is in the midst of a wind farm expansion in West Texas, helping the Lone Star state lead the nation in harnessing clean, native wind energy. With over 1,000 megawatts being installed, 2007 is set to be a record year.

Airtricity North America, Inc. is in the midst of a wind farm expansion in West Texas, helping the Lone Star state lead the nation in harnessing clean, native wind energy. With over 1,000 megawatts being installed, 2007 is set to be a record year.

Airtricity, a relatively young company organized in 1997, is headquartered in Chicago with offices in Austin and Toronto. Having developed wind farms in Ireland and Scotland, the firm initiated its wind power development activities in the U.S. in 2003 and Canada in 2006. This is their first expansion into Texas, which is on its own power grid apart from the rest of the U.S.

Site Choice

Much research and planning goes into locating a proper wind farm site. Patrick Woodson, spokesman for Airtricity, explained the process. A developer looks for an area that experiences steady year-round winds yet also has access to existing transmission lines. Engineers study high elevation wind maps, meso maps, and information from NOAA (National Oceanic and Atmospheric Administration) to learn about an area's wind patterns. They research existing transmission lines that will allow access to the power grid. The necessary land is leased from land owners, paying royalties very similarly to the contracts for oil or gas leases. Airtricity then advertises its projects for competitive bid.

Turbine Construction

Signal Wind Energy, LLC, of Chattanooga, Tenn., a subsidiary of EMJ Corp., completed construction of Forest Creek Wind Farm for Airtricity in Sterling County southeast of Big Spring this past March. This 124-megawatt facility will generate enough electricity to power more than 35,000 homes while avoiding the emission of 225,000 tons of greenhouse gases. TXU Wholesale, a subsidiary of TXU Corp., purchases the electricity generated by this wind farm.

Signal Wind is a general contractor providing Balance of Plant (BOP) services to the wind energy industry. Their contracts normally include building the basic infrastructure such as the haul roads to the job site, upfront design and engineering for each turbine, installation of substations, an electrical collection system to bring the power to one point and the interconnection to the power grid, according to Ben Fischer, president of Signal Wind Energy.

Dressel Enterprises, Inc. was subcontracted to construct the steel-reinforced, cast-in-place concrete foundations. Detailed geologic analysis of the site's soil conditions allows the engineers to determine the proper depth. Great care must be taken to guarantee that tower foundations are level for smooth blade rotation.

"The foundations utilize a rock anchor system consisting of 20 2-1/2-inch-diameter anchor rods passing through a concrete cap and embedded 40 feet into the underlying rock," Airtricity Project Manager Jim Collins describes the process. "The reinforced concrete foundation cap is 24 feet in diameter."

"The turbines for the Forest Creek wind farm were supplied by Seimens' Bonus Energy facility in Denmark," said Patrick Woodson, spokesman for Airtricity in Austin. "When possible, we purchase the steel towers from local manufacturers such as Trinity Structural Towers in Fort Worth, Beaird Industries in Shreveport, or Bergen Southwest Steel in El Paso. That saves on shipping costs."

"Each tubular steel tower is delivered in three sections, varying in length from 18.5 meters to 36 meters," Collins explained. "Siemens Wind Power, of Denmark, the turbine supplier, performed the erection of the turbines. "The turbine towers are placed on shims to assure a level base and bolted to the cap using 160 post-tensioned anchor bolts. The main assembly crane was a Terex-Demag CC2801 with a total lift capacity of 600 tons. The crane was rigged with a jib boom to set the 88-ton nacelle atop the 80-meter tower in winds up to 12 meters/second. A secondary crawler crane with 250-ton capacity was used to accept delivery of the equipment and set the base tower section on the foundation. Auxiliary hydraulic cranes were used as tail cranes and moved miscellaneous equipment."

Siemens used both single blade installation and hub installation, where the blades are attached to the hub and lifted as a unit. The nacelle is the housing that contains the meteorological equipment that points the turbine in the proper direction, the rotors and generators that create the power. The blades are 45 meters long and weigh 12 tons each.

All the tower and turbine components were received at the ports of Houston and Corpus Christi and trucked to the site, according to Collins.

Growing Wind Farms

Airtricity has begun three additional wind farms in the same area, all under construction by D.H. Blattner & Sons, a 100-year-old heavy civil contractor based in Avon, Minn. All three projects are scheduled to be completed by the end of 2007.

The largest of these, the Roscoe Wind Farm, is located west of Sweetwater in an area primarily used for cotton farming. The project area lies at the convergence of Mitchell, Nolan and Scurry counties and will cover nearly 30,000 acres when it is completed by the end of 2007. The 209-megawatt Roscoe Wind Farm will annually produce enough energy to power 60,000 homes and save approximately 375,000 tons per year in greenhouse gas emissions. The wind power will be furnished to TXU Wholesale under a five-year sales contract.

"In 2006, Texas became the nation's leader in installed wind capacity," Woodson said. "There are several wind farms under construction in the 120- to 200-megawatt range. This size is large by national standards, but about average for Texas. Texas accounts for about one-third of the wind power growth nationally this year."

Wind Farm Counties Capacity Turbine Mfg./Location
Roscoe Mitchell, Nolan, Scurry 209 MW Mitsubishi/Mexico, Japan
Sand Bluff Glasscock, Sterling 90 MW Gamesa/Spain
Champion Mitchell, Nolan 126 MW Siemens/Denmark

Panhandle Loop

This past February, a consortium backed by Airtricity announced its plans of a ground-breaking electricity transmission 'loop' in the Texas Panhandle Plains region. As the name implies, the Panhandle Loop is a 'looped' transmission system, with three interconnected transmission lines extending from three separate loops on the grid.

"This project would open an area served by a different power grid, a CREZ (Competitive Renewable Energy Zone), and bring it into the ERCOT (Electric Reliability Council of Texas), the system that operates in most of the state," Woodson explained.

The Panhandle Loop will be a revolutionary 800-mile transmission project bringing 4,200 megawatts of wind energy to the Texas Panhandle — enough to supply over 1 million homes with green, renewable energy. The loop will result in the investment of over $10 billion in new generating capacity, including 2,000 megawatts of gas-fired power and 1,800 megawatts of coal-fired power.

The Panhandle Loop is supported by a group of five unique and diverse companies in the energy and chemical industries: Airtricity, Inc.; Babcock & Brown Renewable Holdings Inc.; Celanese, Ltd.; Occidental Energy Ventures Corp.; and Sharyland Utilities, L.P. The proposal has been filed with the Public Utility Commission of Texas (PUCT).