Advancement of a Tidal Energy Converter Mount Through Integrated Design Process and Risk Management
Authors: Colby Jonathan Austin , Corren Dean Russell , P.E. Mary Ann Adonizio , Hernandez Aaron Antonio 
Published: April 2019

The International Energy Agency Ocean Energy Systems (IEA-OES) has identified a target installed capacity worldwide of 300 GW by 2050 [1]. Verdant Power is advancing the Marine Renewable Energy (MRE) industry towards commercial tidal energy and MW-scale array projects through the development of a scalable mount that integrates life-cycle operation and maintenance (O&M) with an environmentally compatible and scalable turbine. The Verdant Power Kinetic Hydropower System (KHPS) is a 5th generation water-to-wire MRE system that utilizes horizontal-axis turbines installed in fast-moving tidal and river currents to generate renewable energy. The Verdant Power TriFrame™ (TF) mount is a triangular frame mount that supports three KHPS turbines. Verdant will demonstrate this system at the 5m-rotor diameter scale at its Federal Energy Regulatory Commission (FERC)-licensed Roosevelt Island Tidal Energy (RITE) Project in New York City's East River, a highly accessible and well-characterized tidal site.

The technical development of the TF mount is based on an iterated and integrated design and risk management process, all geared to the evolving suite of International Electrotechnical Commission (IEC) marine energy standards and which includes third-party verification of key performance measures. This paper presents an overview of the integrated design process related to innovative mounting systems for tidal energy converters (TECs) that shows potential to reduce capital and operating costs through improved performance, reliability, and maintainability.

With support from the US Department of Energy (DOE) and the New York State Energy Research and Development Authority (NYSERDA), Verdant is conducting an Integrated Design Process (IDP) to develop, build, install, and operate a TF mounting structure supporting three Verdant Power Generation 5 (Gen5) KHPS turbines at the RITE Project. This full-scale, open-water project also includes a demonstration of a periodic O&M cycle. Along with technical performance monitoring, capital and operational cost data will also be compiled. The IDP integrates the capital mount design with the procedures and costs of the associated on-water work (OWW) operations (deployment, installation, retrieval, replacement). The IDP utilizes a risk analysis and management framework for the key components and requires close coordination with partner structural engineers, marine contractors, as well as the system supply chain for fabrication, assembly, and deployment facilities. Numerical modeling tools, component testing, and a failure modes and effects analysis (FMEA) are utilized, following the guidance outlined in International Standards and the National Renewable Energy Laboratory (NREL) Risk Management Framework. The entire process is iterated, with updated feedback from all participants, resulting in an optimized design that addresses project metrics and risk mitigation.

Using IDP, a TEC mounting system design has been achieved that minimizes the time and cost on-water while ensuring structural, environmental, and operational performance. The application of consensus-based International Standards and a clear risk management framework is highlighted throughout the design process and is critical to ensuring system performance and increasing stakeholder confidence across the industry.

Beyond Verdant's RITE project, as the marine energy industry advances, most near-term deployments will likely be at sites driven by supportive national and regional energy and funding policies. The utilization of an IDP, in a standards-based environment, offers a means to develop cost-effective full-scale solutions to capture the opportunities for MRE and specifically, TECs to produce competitive renewable energy.