Tower manufacturer selects thick-steel bending machines

The wind towers and foundations for a Canadian wind farm will be produced using two DAVI 4 roll machines, which are capable of bending plates of high-tensile steel up to 150-mm thick and 3,000-mm wide. The machines are equipped with Davi’s patented High Productivity Package System. “By choosing Davi plate rolls,” says Orazio Davi, President of the company, “Samsung made sure they can meet their future production needs in offshore components, specifically foundations, whether they are monopiles or tripods, where much higher steel-plate thicknesses are required”. Towers are produced by a Samsung subsidiary company in Korea, which has a number of complete DaviWind Towers lines already installed all over the Far East.

Davi
davi.com

How are wind turbine towers changing?

Every horizontal-axis wind turbine needs a tower. Turbines erected in the 1970s and 1980s may have been perched on lattice towers, a design that can scale to 200 ft and more. However, for the protection of the maintenance technicians who must climb the towers, it makes more sense to build them from rolled steel. These protect the technician in long climbs, and better yet, provide a structure that allows installing a service lift. What’s more, the quest for stronger wind will put more recent turbines on taller towers, 100 m and more, and that will require rethinking the design.

Taller towers for wind turbines make sense in many ways. For instance, an 80-m tower can let 2 to 3-MW wind turbines produce more power than if installed at 60 m, and taller towers will let larger turbines enter the market. Taller towers also allow putting turbines in less turbulent winds, thereby decreasing their wear and fatigue.

As OEM designers configure taller conventional towers, their limitations become obvious.

Tower designers are increasingly interested in:

• Reducing their cost because the tower- cost portion of the overall wind turbine is increasing from 10% to 20% of system cost.

• Cutting tower transportation costs.

• The interaction between tower and turbine

• Focused on reducing weight

Several designs have been proposed. One uses prestressed, reinforced concrete in tubular form. Another developer has shown detailed plans for tapered modular towers. Its developer says the continuous taper or an increasing taper is the most efficient way to handle wind-turbine loads. One design, for example, uses field-assembled panels to eliminate transportation restrictions. Shipping tower panels instead of assembled towers allows lower loads and lower load heights, which lead to shorter less restrictive routes, and hence, lower transport costs.

Adding tower panels allows increasing tower diameters and heights. There are other bonuses here. Increased diameters allow for thinner tower wall thicknesses, which uses steel more efficiently and lowers weight and cost. Flanges at the tower top and base allow for a conventional interface with the turbine and foundation. Flanges use the same mounting criteria as conventional towers.

The larger bottom diameters than conventional foundations require less depth. This eliminates need for costly embedment rings often used in conventional foundations.

GE: a busy bee with turbines and towers

Looks like GE’s been busy lately, though for one of the world’s largest companies that in itself is nothing new.

What is: For one, the turbine manufacturer recently installed its 15,000th 1.5-MW model at Basin Electric Power Coop.’s Crow Lake wind farm in South Dakota. The turbine is one of 108 GE units commissioned at the site, and will be owned and operated by Mitchell Technical Institute (MTI),  providing a learning opportunity for students in MTI’s Wind Turbine Technology Program.

MTI was able to fund the project through a grant from the U.S. Economic Development Administration, as well as funding from the South Dakota Governor’s Office of Economic Development, Basin Electric Power Cooperative, General Electric and MTI. Construction at Crow Lake began in October of 2010. GE says the project spans three counties in South Dakota and is the largest wind project in the United States owned solely by a cooperative, with a capacity of 151.5 MW.

In other news, GE has also acquired technology from Wind Tower Systems that will allow taller towers, while lowering installation and transport costs.  The need for taller, cost-efficient towers is becoming an important factor in the wind industry as blade lengths increase. WTS has been working on the development of a space frame tower system for use at wind farm sites that require hub heights of 100 m or more. The manufacturer says the tower will handle static and dynamic loads generated by the turbines.

WTS also has focused on ways to transport and install these taller towers. They will use standard flatbed trucks and a hi Jack system to eliminate the need for heavy-lift cranes. These developments help cost effectively extend the tower height, which in turn enables the turbine to produce more energy. As Victor Abate, vice president of renewable energy for GE Power & Wind, explains, “Taller towers are an important complement to longer blades. Longer blades capture more energy and in turn improve return on investment for wind farm developers.” Plans are underway to install a prototype of the GE’s space frame tower system to test later this year, with commercial availability targeted for 2012

GE www.ge.com

Steel facility in Kansas to produce new wind tower

A wind tower manufacturing plant is planned for Ottawa, Kansas. Schuff Steel Company, a subsidiary of Schuff International, Inc.— a family of steel construction companies — is moving ahead with their plans. “We are currently building a first article prototype wind tower at our plant in Ottawa, Kansas and are pursuing opportunities for volume manufacturing of the tower,” says Dennis Randall, executive vice president of Schuff’s Midwest Division. According to Randall, “Volume manufacturing of this new type of wind tower would require construction of a new plant.” Construction documents are being prepared for construction of the 200,000-sq ft facility at Schuff’s current location on Davis Road. Schuff anticipates employment of 200 to 250 people for the facility once it is at full capacity.

The plant would produce a new type of tower for Wind Tower Systems LLC, but the new product must be accepted in the marketplace to justify the manufacturing plant, according what Randall told the Kansas City Business Journal. The new design is a structural tower wrapped with fabric rather than the conventional rolled-metal tower. Randall says the design is more economical to ship and to accommodate taller towers.

Demand for the new tower is expected to develop in early 2012, giving Schuff plenty of time to build the plant if it can secure sufficient orders. Early preparation of construction documents is expected to aid in this effort. Schuff had originally planned to build the plant in North Dakota, but changing market conditions and providing a location central to the wind belt were factors in the decision to relocate the planned facility.

Wind Tower Systems www.windtowersystems.com

Cylindrical Towers are the Secret to Capturing More Wind

A classical image of fluid flowing around a cylinder shows it speeding up at the sides and slowing or stagnating at the front and back. This let Majid Rashidi, Professor of Mechanical Engineering at Cleveland State University, realize that placing wind turbines in the naturally forming high-speed areas at the sides would let them generate more power than if the turbines were free standing. To test his hypothesis, Rashidi applied for a two-year grant from the Dept. of Energy and NREL, won it, and built a 25-ft diameter cylindrical tower on the roof of a CSU building. His idea mounts a pivoted truss across the top of a cylindrical tower to extend beyond its circumference. Arms extend down from the end of the truss to hold four 2-m diameter turbines (two on each side). The turbines are the off-the-shelf Swift design from Cascade Renewable Energy Solutions, Grand Rapids, Mich. Each is rated for about 2 kW at max wind speed.

Controls and monitors nearby show what each turbine is producing. During my visit, an almost calm morning, the control turbine some 150 ft away was barely turning in the light breeze while those by Rashidi’s cylinder were spinning much faster. And when the wind picked up, the turbines made no discernable noise, partially because the circular rim prevents vortex shedding at the blade tip, a noise source. The existing design uses a time averaged control to turn the device into the wind. But Rachidi plans on testing a passive less expensive directional fin, like a weather vane, for the same function.

The CSU professor says his design improves power capture by three to four fold. In addition, the design would be ideal for retrofitting existing round structures such as silos or water towers that adorn many rooftops in large cities. Rashidi says the school owns the technology and is still in the proof of concept stage. Commercialization would be a next step.

Two to build wind towers

To serve North American markets, Martifer Energy Systems and Hirschfeld Wind Energy Solutions say they will form a joint venture to manufacture wind towers and related components in the U.S. The joint venture, Martifer-Hirschfeld Energy Systems LLC, will be equally held by each party. The company will develop a factory in San Angelo, Texas, to build steel towers for wind turbines. The investment until now was developed solely by Portugal-based Martifer Energy Systems, and represents about $40 million which generated 225 jobs. The companies plan two stages, with the first representing an investment of about $30 million and completion expected for Q2 2010. The factory is expected to reach a capacity of 400 towers/yr by 2013.

This venture joins the expertise of Martifer Group for manufacturing wind-power components along with Hirschfeld’s local footprint and experience in infrastructure fabrication. Martifer Energy Systems produces towers, coverings, and gearboxes for wind turbines.  Through a joint venture with REpower Systems AG of Germany, Martifer designs and manufactures wind turbines, and it assembles REpower wind turbines in Portugal. The company also builds wind farms for third parties.

Where to place wind towers wins $10,000 prize

A clever idea from a French team of engineers and architects is to build vertical-axis wind turbines into existing towers that carry high-voltage power lines. The idea was good enough to win a $10,000 Metropolis Next Generation Design Prize.

Judges say Wind-it, winner of the Metropolis Next Generation Design Prize, solves the problem of linking energy generation and transmission by mounting vertical-axis wind turbines inside transmission towers.

The team, Julien Choppin, 31, and Nicola Delon, 31, are partners in Paris architectural firm. Also sharing the prize is Raphaël Ménard, director of a 20-person design firm.
The concept behind the winning design, called Wind-it, answers one challenge to developing wind power: where to site turbines. The idea uses existing infrastructure, the towers and pylons that carry more than 157,000 miles of high voltage lines in the U.S. The proposed turbines can be stacked within already sited towers. No design details are available as to weight, cost, or efficiency of the proposed turbines.