Wind turbines and their blades look large from a distance, but up close they’re downright massive. That makes the blades difficult to transport on curved roads and railways designed to support the transport of much smaller items. The challenges are increasing as longer, more efficient blades gain popularity.
Segmented blades — those that come in more than one piece — improve product transportation, but they carry some cost concerns. The National Renewable Energy Laboratory in Colorado determined that manufacturing blades that can bend via “controlled flexing” will allow railroads to ship longer blades.
Currently, 75 meters (about 250 feet) is the blade length limit for rail transport, but NREL says controlled flexing could extend the limit to 100 meters (330 feet) or beyond. This could help expand the portions of the country in which land-based wind turbines are a viable power source.
“This research can aid in massive deployment of wind energy in different regions of the country — even parts of the country that typically haven’t seen as much deployment,” Nick Johnson, a mechanical engineer at NREL’s National Wind Technology Center, said in a news release.
The scientists released a study that examines five next-generation designs for a 5-megawatt turbine installed on a 140-meter (460-foot) tower. They concluded that traditional blades already carry some flexibility, with bendability up to 10% of the blade length from tip to turbine attachment. Increasing that to 20% allows for rail transport.
The study mentions some areas that need work before blades with more bend are commercially viable. For example, they concluded that downwind turbines with flexible rotor blades run the risk of the blades striking the tower, and manufacturing the blades with certain carbon fibers that allow flexibility and better aerodynamic performance is more expensive.
Johnson said this concept’s “impact could be significant” for the wind power industry. With continued work on the details, he estimates that the industry could adopt the flexible blades in about five years.