Verdant Power’s three-turbine tidal energy array has generated 200MWh of tidal power to the United States electricity grid in its first six months of continuous operation, marking the country’s record for marine energy production. The company will now move forward with a retrieve-and-replace (R&R) operation for one of the turbines.
The turbines, mounted on Verdant Power’s proprietary TriFrame, performed at over 99% availability, and overall water-to-wire efficiencies reached to over 46%, according to the United States Department of Energy (U.S. DOE).
The array was installed in the East River in New York in October 2020 as part of the Roosevelt Island Tidal Energy (RITE) project.
This spring, Verdant Power will be performing a R&R operation during which one of the turbines will be replaced with a rotor housing three thermoplastic blades manufactured by DOE’s National Renewable Energy Laboratory (NREL).
While the aim of the project is to demonstrate a streamlined installation and maintenance approach and long-term system reliability, the R&R operation will offer numerous data points for Verdant Power and NREL, according to U.S. DOE.
The preparation, design, and execution of the R&R maintenance cycle will be evaluated for levelized cost of energy through on-water time and equipment required to service the TriFrame.
The Verdant Power team will examine the entire R&R process, from preparation to design and execution. By inspecting the TriFrame system, the team can make necessary modifications before redeploying it for the second six-month monitoring period, U.S. DOE informed.
The team will also download and analyze the data from the first period of deployment collected from October 2020 to spring 2021.
The lessons learned will inform future deployments for Verdant Power and others in the marine renewable energy industry, according to U.S. DOE.
NREL, meanwhile, will focus on the blades themselves. After retrieving the TriFrame mount, Verdant Power will replace one of the Gen5 epoxy blade turbines with another that uses NREL-manufactured thermoplastic blades.
NREL produced these thermoplastic-fiberglass composite blades to be identical to the epoxy blades already used on Verdant Power’s tidal turbine system, but the thermoplastic materials could prolong the life of the blades and have improved structural properties, according to U.S. DOE.
Over the next six-month deployment of the Verdant Power TriFrame mount, NREL’s data acquisition system will measure blade loads for the fourth turbine.
Following the deployment, the blades will return to NREL for structural validation and material characterization to help researchers better understand why certain materials perform better in seawater than others.
Thermoplastics at a smaller scale have been shown to have improved saturated or seawater condition properties compared to other traditional materials. NREL anticipates that the thermoplastic blades could be a game-changing material for marine applications at a meaningful scale, according to U.S. DOE.
The entire operation – from Verdant Power’s aim is to demonstrate a streamlined installation and maintenance approach, and system reliability, to NREL’s loads data analysis and materials research – has the potential to inform future materials and turbine deployment across the marine energy industry.