Later this year, the Block Island Wind Farm on Rhode Island will be completed—the first offshore wind farm in the United States.
Bentley takes pride in playing a vital role in the engineering design of this wind farm. Its Offshore Structural Analysis and Design Software, or SACS, was used in designing the substructures of the wind turbines. In other words, Bentley helped to create the literal foundation of this celebrated engineering project.
The Substructures That Will Support the Offshore Wind Farm
The substructures are vastly different from typical offshore energy operations. Instead of the regular monopole concrete foundations, they are supported from a type of steel lattice that is slightly twisted.
The substructures are based off of the Inward Batter Guide Structure (IBGS) design, also called the “Twisted Jacket.” Created by Keystone, the type of substructure was first installed in the Gulf of Mexico in March 2005 as part of the Louisiana-based West Delta oil rigs. That summer, Hurricane Katrina devastated the region, but Keystone’s IBGS was left unscathed.
Ten years later, Keystone is bringing its substructure design for its oil and gas offshore operations to the new offshore wind energy facility—this time with a design that is new and improved with SACS software.
How Offshore Engineering Software Was Used
By integrating SACS software with DNV GL’s Bladed, a wind turbine simulation tool, Keystone helped to optimize the design of its substructures through a rigorous set of virtual tests.
The design team conducted 2,334 simulations, 30 million time steps and 25 load cases for waves up to 19 meters high and winds from eight directions at speeds ranging from 2 meters per second to 58 meters per second. The different load cases that were taken into account include operating, storm, startup, shutdown, fault, maintenance and installation.
Using SACS, Keystone performed more than 3,000 time domain simulations for each design iteration and conducted more than 150 simulations in parallel. This reduced cycle time by 50 percent compared to typical European offshore wind projects.
The energy needed for these simulations required five 24-core computers running 24 hours a day for 10 days. SACS allowed Keystone to streamline the design and analysis of the simulations and manage terabytes of project data accurately to minimize the possibility of errors.
With extensive simulation tests, the process helped to optimize the design of the total structure to ensure that it operates safely under a wide range of weather conditions.If the results from the virtual tests hold true, the new structures supporting the Block Island wind farm should be able to withstand 100-year tropical storms (or a storm in which the intensity is so great, it only occurs on an average of every 100 years).
This is not only sustainable, but it will also produce savings in the long run. An avoidance band in the operating speed of the turbine could mean a 50 percent loss of energy production over the lifetime of the turbine.
The foundation is also sustainable to manufacture, as it requires less steel than comparable substructures. It can also operate in a much wider range of weather conditions than offshore structures found far off the northeast coast of the United States.
To learn more about what innovative design is being incorporated into the Block Island wind farm. Visit the websites of Bentley and Keystone.