Project / Heavy Lift

University of Delaware researchers say U.S. offshore wind ports need to be bigger

Two University of Delaware researchers say that U.S. ports, designed to support offshore wind farm construction, are currently too small and will not support the growing number of wind farms and wind turbines that have blades over 300 feet long.

The April 2022 report ‘Marshaling ports required to meet US policy targets for offshore wind power’ was authored by two University of Delaware researchers, Sara Parkinson and Wilett Kempton.

Report Findings

“U.S. marshaling ports are currently insufficient to meet either state or federal power targets. We calculate state commitments from state contracts and policies: in sum, 40 GW by 2040. Federal targets from the Biden Administration are 30 GW by 2030 and 110 GW by 2050. Either target yields more demand for marshaling area than is currently available or planned. The shortage of marshaling area supply has incorrectly been attributed to lack of suitable U.S. locations. Instead, we attribute it to developers having built ports to support early, smaller projects … Additional land suitable for marshaling ports exists, but it requires commitment from port authorities and port investors to develop it for this purpose.”

The authors explained that a 1 Gigawatt (or 1,000 Megawatts) Offshore Wind Project will currently require 83 x 12 MW wind turbines.

“Modern projects are specifying turbines with capacities of 12–14 MW, with hub heights of 138 m and blades of 107 m each. The nacelles weigh 600 tonnes, and each blade is 55 tonnes, thus requiring the use of a heavy-lift ocean-going crane. Assuming a 1 GW (1 Gigawatt = 1,000 Megawatts) OSW (Offshore Wind) project uses 12 MW turbines, 83 turbines of such technical specifications would be deployed (1000 MW ÷ 12 MW = 83 turbines).”

The report says that “a 1 GW wind project is approximately the power capacity of a nuclear or large coal power plant. Given typical offshore wind speeds, varying over time, a well-designed offshore turbine will produce on average about half its maximum capacity.” For example, “an offshore turbine with 12 MW capacity would have an average output of 6 MW, enough to power 4,000 US households or charge 1,000 electric cars simultaneously.”

Thus a 1 GW project that would require 83 x 12 MW wind turbines will power 332,000 households or charge 83,000 electric cars.

The support for multiple 1 GW wind farms will require major increases in U.S. manufacturing and upgrades in the U.S. supply chain.

“As there is currently no robust supply chain in the US to support the nascent industry, OSW project developers are reckoning with how to work around the lack of US-based infrastructure. Importing all components from overseas runs into several problems:

  • Europe’s offshore wind manufacturing facilities will already be strained to meet its own offshore wind goals.
  • Developers have been hesitant to rely on early-stage Asian manufacturing in which they do not yet have confidence
  • As the components are very large, additional loading and unloading for trans-ocean shipping adds cost and logistics … The above logic as well as the Biden Administration’s employment priorities lead toward investing in and supporting US-based manufacturing of OSW components. Substantial investments in manufacturing will be required to meet state and federal targets.”

Port Types Needed to Support Offshore Wind Projects

Small oceanic ports for survey vessels: “These ports service the launching of survey vessels used for wildlife surveys, seafloor scans, and geotechnical boring. Ports and vessels already exist for these purposes and may already be sufficient for new OSW use. If not, these ports do not pose significant cost or acquisition and build challenges that would impede further construction.”

Manufacturing ports: “OSW components are made on land but are so large they are impractical to transport over land—e.g., modern blades are 107 m (351 ft), much longer than a semi-trailer maximum length of 16 m (52 ft), and longer than the maximum railroad flatcar length, 27 m (89 ft). Thus, OSW component factories are located within or directly adjacent to a port, so finished components can be moved to the quay via “self-propelled modular transporters” (SPMTs) and loaded directly on a transport ship for transfer to a marshaling port.”

Marshaling ports: “Just prior to loading out, all components are collected, stored, and made ready at a marshaling port. Here, components are loaded onto assembly vessels to build the wind project at sea. Our analysis, derived in conjunction with two wind turbine Original Equipment Manufacturers (OEMs), shows that a single 1 GW project with 12–14 MW turbines would occupy 22 ha (54 ac) of such a port for two years during the construction period.”

Operations and Maintenance (O&M) ports: “O&M ports have a smaller geographical reach than other OSW ports. They typically have 1 or 2 small craft serving one project with daily visits. However, with projects further from shore, the conventional model is shifting to using a larger O&M port (say 10 ac, as opposed to 5 ac) and a service operation vessel (SOV) moored on the project site for multiple days, housing a constant crew who service one or more wind projects.”

The study says a forward-looking marshaling port design should consider at least 15 MW turbines with 120 m blades and prepare for future 25 MW turbines with 156 m blades.

As a result, the two researchers say a port consisting of 54 acres may be a better fit: “We have analyzed requirements for modern OSW turbines (12 MW - 14MW), and today’s cost-effective project size (about 1 GW), thereby finding that each such project requires an area conservatively of at least 54 acres (22 ha) over two years. This is conservative in that even larger marshaling ports are preferred—like those in Europe—for the purposes of streamlined supply chains, reduced vessel time, less logistical complexity, and corresponding cost minimization.”

Right now, there is only one large OSW port in the United States at New Bedford, Massachusetts: “Unlike Europe, the US has just one operational marshaling port: the New Bedford Marine Commerce Terminal, in New Bedford, MA. This port is 29 ac (11.7 ha) and was originally designed for the Cape Wind project with turbines of 3.6 MW each. Now, New Bedford has been leased to help marshal the significantly larger 800 MW Vineyard Wind 1 project, with turbines of 13 MW each. Due to limited port area, parts will have to be marshaled among three regional ports to accommodate the project’s size and target power-on date. This increases the cost, logistical challenges, and time of the project’s installation, while also complicating port availability for other projects set to be deployed within the same region and time period. The need to use three ports for a single project already demonstrates a shortage of US marshaling ports of sufficient area for modern turbine and project sizes.”

In the case of deploying floating wind turbines there are additional structural requirements: “For example, floating developers have requested a load bearing assembly area in the water, just off the quay, with cranes on the quay lifting components to assemble in water. Alternatively, assembly could be done in dry dock, making a gantry crane possible, if the dry dock has sufficient width for the floating platform base.”


In a table, listing marshaling port requirements the researchers suggest that requirements could encompass a land area of between 100 to 200 acres (40-80 hectares) and the following additional requirements:

Channel depth

20-36 feet (6 to 11 m)

Vessel width

150 feet (46 m)

Maximum current along quay

5 knots (2.6 m/s)

Quay length

1,300 feet (400 m)

Lay down area loading

1,200 psf (pounds per square foot) (6 ton/m2)

Quay/Lift area loading

3,000-6,000 psf (15-30 ton/m2)

Overhead clearance

120 meters

Authors’ Conclusion

“Based on our assessment of port area, our calculations show that the supply of US marshaling port infrastructure will be insufficient for firm state demand by 2023 and far short of that needed for projected demand through 2050. We find that existing OSW demand, projected OSW growth, and the development of a sustainable domestic industry and supply chain will depend on early action of government, port authorities and/or port investors to plan and develop suitable marshaling ports.”

Stas Margaronis
Stas Margaronis


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