DoE Research Promises Taller Wind Towers

Spiral Welding Presents New Breakbulk Opportunities

New research into on-site welding techniques for wind farms promises to drive turbine heights to record levels, changing current limits on breakbulk transport.
Equipment developer Keystone Tower Systems demonstrated its new on-site spiral welding process, which offers the potential to create towers of up to 180 meters in height.

"Blades are using less efficient airfoils due to geometric constraints ... towers are highly under-optimized due to the 5.2-meter bridge limit,” said Owen Roberts, from the U.S. National Renewable Energy Laboratory, or NREL in comments to New Energy Update.

The firm estimates a reduction in cost of energy by as much as 90 percent, based on a height of 160 meter and a tower cost of US$200 per kilowatt.

DoE Grant
Research into the spiral welding process was funded by a US$5 million grant from the U.S. Department of Energy and offers the potential to simplify breakbulk transport of outsized blades by creating a modular approach, with towers largely assembled on-site.

“Keystone mills can be operated at the wind project, enabling towers that are far larger than today’s transport constrained towers,” a spokesperson for Keystone said.

The steady increase in turbine size, driven by efficiency gains, has placed additional pressure on breakbulk operators, with U.S. tax regulation changes adding further in the fourth quarter, according to consultancy Wood Mackenzie.

7-meter Diameter
Current transport requirements restrict tower diameters to roughly 4 meters, equivalent to one-piece tower designs of about 80 meters.

Keystone’s new technique promises to allow for towers in excess of 7 meters in diameter at competitive costs. This in turn is expected to raise the working average wind speed by to 1.5 metres per second, according to data from NREL.

Based in Westminster, Colorado, Keystone is working with leading wind turbine manufacturers to integrate large diameter, field-welded towers into their turbine offerings