Over the last few years, a 1.5-MW wind turbine has been a prevalent size on U.S. roads and wind farms. It is about the largest and heaviest that transports easily on most U.S. roads. But turbine design is trending to larger units, hence, 2.5 and 3 MW units will soon be more frequently encountered. These will be challenges for transport and construction companies because each state has different rules, and approved routes change as frequently as does the wind. This is potentially bad news for wind farm developers that expect to stay on construction schedules.
Larger equipment presents a transportation challenges because of the weight and size limits imposed by most state departments of transportation (DOTs). “It seems that logistics can sometimes be left last in the design processes,” says Alan Redding, director of sales and marketing with transport firm ATS Wind Energy Services, St. Cloud, Minn. “If there is a message for turbine manufacturers, it’s that they should start thinking about modular turbines that can be shipped below the upper limits imposed by most state DOTs. Otherwise, they could face a boat-in-the-basement problem, one in which the size cannot fit through restrictions set by state DOTs.”
Tower sections provide an example because they are tremen-dously heavy. Typical lengths run from 60 to 70 ft and more with 15-ft diameters, and weights of 100,000 to 150,000 lb. “This is a huge part. We transport tower loads on special equipment called a Schnable trailer, one with many axles. We need an approved route before getting a permit, and approved routes can change from day to day. That is frustrating for our customers and us because it can be difficult to react to these changes. We are very proactive and try to foresee the potential restrictions or choke points so we can implement alternative routes and measure as soon as possible. We are always working with federal, state, and local governmental agencies to find the best solutions to the route adjustments. These routing adjustments are just a reality and parties involved work constructively to find solutions,” adds Redding. A few turbine OEMs are already designing in modules to alleviate shipping problems, he adds, but some modular designs are more efficient than others.
“Many turbine OEMs trying to enter the U.S. market don’t understand the DOT and its requirements that we operate under. Thus, a firm building a reliable turbine may be working in a vacuum. Some of these designs, when broken into sections for transport, don’t make a lot of logistical sense. I know there are many factors in play. But project schedulers –could expect delays for anything over a 2.3-MW machine that is moved intact, unless the OEM has a special design in which it worked closely with a company like ours to fit it nicely within the confines of a trailer,” says Redding.
There are a lot of transport regulation similarities, but there are also a lot of differences from state to state regarding how much weight is allowed per axle or grouping of axles. “It’s somewhat fragmented. We’ve been in this business over 50 years, and it’s sometimes difficult for groups trying to understand how we price jobs because what one state has for permitting and structure, another may not. One state may have wind targets to hit so they want to streamline approvals as far as permits and escorts go, while another state may not. The bottom line: regulations are complicated and involved,” he adds.
Jobs are simplified with intrastate loads, one that begins and ends in the same state. “Going from east to west Texas is pretty easy. But when traversing multiple states, say from Texas up to Minnesota, the states in between know the project is not theirs, but they get the impact of the heavy equipment, so they can be less accommodating.” Redding says he has been working on national transport standards for years through an industry group, Specialized Carriers and Riggers Assn. (scranet.org).
The idea to drive home is that OEMs must bring logistics into their design discussions when they come to the large weights and sizes common in the wind industry. Turbine designers must be involved with how to get equipment from point A to B. There are OEMs that have done this extremely well, and those that have been less successful. The hazard is that those that have done it poorly might be uncompetitive. At the end of the day, OEMs must have lowered their land-cost options. Not allowing for that puts the OEM at a disadvantage. WPE
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