University of Maine researchers are completing the design and engineering work for a full-scale floating hull for the proposed 12-MW Aqua Ventus I offshore wind farm.
This milestone follows, in 2014, the successful deployment of the Volturnus 1:8-scale model, the first grid-connected floating offshore wind turbine in the nation.
A $3.7-million award from the Dept. of Energy, announced last November, will help underwrite completion of design and, within the next year, permitting and obtaining power purchase agreements to allow for construction of the two-turbine project, says Habib Dagher, director of the Advanced Structures and Composites Center (ASCC) at the University of Maine in Orono.
This award puts the project on a level playing field to compete with three other offshore wind developers in New Jersey, Virginia and Oregon for an additional $40 million, to be awarded by DOE next spring.
Jake Ward, the university’s vice president for innovation and economic development, says the university is developing a “statement of project objectives” (SOPO), including a final cost estimate, to obtain final DOE approval for the award.
If the project secures the DOE award next spring, construction is expected to begin in 2017, with connection to the grid the following year, Dagher predicts.
The researchers claim the Volturnus hull design is the lowest-cost offshore floating wind-turbine design in the nation. The team has completed 11 cost estimates from nine contractors for building the hull in the U.S. Offers have come from the East Coast, the West Coast and the Gulf of Mexico, Dagher says.
Nine domestic and two international contractors provided the estimates, and the team plans to add one or two international cost estimates. “The numbers came in favorably,” Dagher says. “We’re very pleased it turned out the way we anticipated.”
The team also has built a quarter-scale version of the hull and lab-tested components for fatigue, system and joint durability, and corrosion. “It was all done to look at the durability of the system in an ocean environment,” Dagher says. “We proved that we can achieve a 100-year life with the hull.”
Last year, the team successfully completed the deployment of the 1:8-scale Volturnus, bringing back the unit to the lab for inspection. “We took it apart and, during inspection, found no fatigue, no fractures and no damage in the concrete,” Dagher says. “The design works, and now we have full confidence in our engineering models.”
Currently, the lightweight concrete trimaran-hull design is 90% complete and cost estimating is “wrapping up,” Dagher says.
After deciding where to build the wind farm, where to fabricate the components, how to launch the operation and the number of subcontract bids to issue, the team then will focus on installation, operation and maintenance. Cable transmission work for the offshore and land segments will begin this year, with bids going out beginning in June. The contractors include two Maine-based firms: SGC Engineering, Westbrook, for the electrical engineering design and Cianbro, Pittsfield, for construction. Omaha-based HDR is aboard to manage permitting.
Other work includes closing on debt and equity financing. “Over the next year, it has to be certified by a third party, including debt and equity partners,” Dagher says.
Dagher says Maine and the world have shown significant interest in the Volturnus. “We are in discussion with groups in the U.S. and abroad. [There is interest] in using the design abroad,” he says.
During deployment of the Volturnus, which is equipped with 60 sensors, the team observed 37 storms, ranging from a 50-year to a 500-year storm, with the equivalent of 70-ft-high waves. “This provides a unique data set that doesn’t exist anywhere else in the world. [It] show what happens to hulls in a 500-year storm,” Dagher says.