Session: 09-09-03 Hybrid Energy: Concept and Analysis

Submission Number: 180644

Feasibility Study on the Incorporation of Wave Energy Into the OCG-Data 

The OCG-Data platform is an autonomous, self-powering, multi-instrumented platform designed to gather pre-deployment data for the development and permitting of offshore renewable energy projects. Compared with other metocean or biodiversity assessment buoys moored to the seabed, OCG-Data has a larger footprint. For example, Ocergy’s Blue Oracle has a 28 m diameter. These dimensions are clearly an asset for hosting instruments that are motion sensitive, like bird radars, or for installing a wide range of instruments and power production capabilities. A demonstration unit has been operating in the French Mediterranean Sea since 2023.

The OCG-Data is currently self-powered using solar panels, wind turbines, and lithium batteries for energy storage. The Mediterranean site has ample wind and solar resources to power onboard instrumentation, but when deploying OCG-Data platforms in a wider variety of locations globally, the wind and solar resources may not be as abundant, potentially jeopardizing the ability to meet the continuous power demand required to maintain high availability of the onboard instrumentation. Ocergy would like to continue diversifying the power sources by adding wave energy converter(s) (WECs) to address power intermittency on the OCG-Data and increase the continuous power draw for the onboard instrumentation. Much of the available space above water is already claimed, which limits the expansion of solar and wind power generation. Incorporation of WECs, which can be placed adjacent to and connected on the end(s) of the platform, maximizes use of the OCG-Data footprint, and weight concerns can be offset by the WEC buoyancy. Ocergy estimates that the existing power and storage system can provide 2 kW of continuous power. This feasibility study will evaluate if the addition of WECs to the OCG-Data can contribute an additional 2 kW of power, thus increasing the continuous power draw by 100%. 

The proposed WEC concept is a float with a submerged hemispherical or cylindrical volume attached to the outer columns of the platform via a linkage arm that, through a pitching motion induced by the relative motion of the float against the platform, drives a power take-off unit. WEC-Sim will be used to model the platform augmented with a set of four of these WECs in various configurations. WEC-Sim uses MATLAB/Simulink to model the six degree of freedom dynamics in the time domain and will be used to calculate the electrical power assuming a 50% conversion efficiency (from mechanical to electrical power). The study will also consider the mechanical loads (PTO torque and joint forces), impacts to the platform response, and relative motion between the WECs and platform. The multi-body model will be simulated in sea states provided by Ocergy to estimate annual energy production for continuous power estimates, and peak power for future generator ratings. If WECs can meet the goal of 2 kW continuous power, it will warrant further investigation by Ocergy into more detailed WEC design and models.

Presenting Author: Alexia Aubault Ocergy, Inc.

Presenting Author Biography: Alexia Aubault is the chief technology officer (CTO) for Ocergy, Inc. Alexia has worked in Offshore Wind for more than 10 years, with a focus on the emerging floating wind industry. A naval architect and offshore engineer, with an M.S. from U.C. Berkeley, Alexia has pursued work in offshore renewable energy before it became a thriving industry in the U.S., working on various projects, in design, execution and operations. Now, at OCERGY, the organization enables offshore renewables by promoting smart products to cut costs and help industrialization.

Authors:

Jeff Grasberger Sandia National Laboratories
Nathan Tom Ocergy, Inc.
Alexia Aubault Ocergy, Inc.