Why Adaptation Is the New Reality for Offshore Wind Energy Logistics

Everything about the wind energy business is getting bigger. For example, current turbines averaging 4.1 MW with a hub height of 90 meters will soon be replaced by 11-MW giants with hubs 125 meters off sea level and blades spanning 190 meters. Their blade tips will cut the air at well over twice the height of the London Eye.

Offshore turbines will be particularly affected. Aleksi Minchev, marine and port operations specialist with WWL ALS (International) Ltd., predicts that offshore will be the growing market for the renewable sector.

“Onshore wind farms will obviously still be in the market, but more focus will be on the offshore as advancements in technology now means that there are capabilities to handle bigger turbines with more capacity, so reducing the number of turbines needed to be erected on the land,” Minchev said.

As offshore wind turbine components have increased in size and weight, it is becoming almost impossible to transport the blades, towers and nacelles by road or rail. “This is encouraging wind turbine manufacturers to shift their production facilities to the ports” he said.

Outmoding Conventional Transport Models

To service the rise in size and weight of wind turbine components, a suite of dedicated facilities for handling and transporting them have grown up, including new or converted roll-on/roll-off vessels, longer blade trailers, self-propelled modular trailers (SPMT) and blade adapters.

Purpose-built new roll-on/roll-off vessels handling bigger turbine components make regular weekly deliveries to Siemens in Hull, and according to Minchev, such vessels will transport offshore wind turbine components between Siemens Wind Power’s facilities in Hull, Cuxhaven, port Esbjerg and other installations. These vessels have specially developed bows and extendable ramps controlled by hydraulic systems and are able to carry up to 12 wind turbine rotor blades. The advantage, as Minchev points out is that “loading and discharging such vessels are more cost-effective by roll-on/roll-off vessels than the conventional lifting method.”

Related: Scotland Breaks Offshore Wind Records with Powerful Turbines and Innovative Foundations

Heavy capacity hydraulic modular trailers, or SPMTs, with many axels are being increasingly used to drive components such as nacelles weighing over 350 tons onto and off roll-on/roll-off vessels. SPMTs are more cost-effective in mobilizing loads than conventional cranes. SPMTs can be combined with barges to use the inland waterways. Barges are also used not only for wind turbines but other heavy cargoes such as transformers and generators.

In sum, the main purpose of these vessels and wheeled equipment is to reduce the number of crane operations needed to place components under the installation crane hook.

Offshore, the use of larger turbines has been facilitated by the development of floating offshore wind turbines, which as their name suggests float rather than being fixed to the seabed, by the conventional monopole rigid structures mounted on the seabed. Another innovation is the offshore jack-up vessel equipped with big capacity cranes to lift heavy nacelles.

Highways and Byways Bring Special Adaptations

According to Minchev, a key innovation for the wind energy logistics sector has been the blade adapter. This specialized piece of kit allows a truck loaded with a wind blade to negotiate tight road bends by raising the tip end of the blade vertically. The blade adapter allows blades between 57 and 65 meters to be carried by road to onshore wind farms.

Moving such large wind components can prove a challenge not only for logistics operators but also for highway authorities. For instance, the U.S. Department of Energy reports that a 1,000-mile truck trip can cost more than $20,000. This is a small sum to pay compared to the $3.3 million price of an average wind turbine. However, with three blades per turbine and the 100 turbines that might make up a wind farm then the cost of transport alone amounts to a hefty sum.

In response to the potential impact that transporting such big and heavy loads can have on transport infrastructure, Holger Gerhardt, project manager at Siemens expects more regulations, especially “greater restrictions on the actual routes taken as well as on the diameters and loadings of such equipment that can be moved to protect public infrastructure from damage.” Gerhardt notes that there are solutions to most logistical challenges if money is available for them. The trouble is, using cranes to lift equipment over obstacles before reloading equipment onto trucks can only be justified if the project can pay back the expense. Gerhardt said that “as a component provider we need to make sure we produce components we can transport.”

One thing is clear; we could see the size of components limited by regulations, which will force wind energy manufacturers to break up their components into smaller modularized sections, so as to overcome the logistics and regulatory challenges of transporting such technology.

Lead image credit: CC0 Creative Commons | Pixabay

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Nicholas Newman is an international energy journalist based in Oxford, England. He specializes in the topics of oil and gas exploration and production together with power generation, including renewables and nuclear.

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