Robert J. Cavagnaro

The project goal is to develop a floating solar photovoltaics (FPV) tracking & position system that: (1) increases annual energy production of FPV projects by >10%, (2) lowers levelized cost of energy (LCOE) for FPV by >10%, and (3) leverages U.S. contract supply chain & manufacturing. The outcome of the project will be a certified tracking product that has undergone extensive field testing and is ready for commercial sales. The primary objectives for each budget period are: • BP1: Define product requirements, develop initial controls architecture and design other sub-components, complete small-scale pilot testing, install a larger-scale pilot, secure sites for commercial pilots, and develop the beta-version of a user portal. • BP2: complete control system and sub-component design, successful demonstration and testing at a commercial pilot, certification & bankability, finalize user portal, and complete various commercialization activities related to supply chain, customer acquisition, and sales. PNNL will provide support during both project phases for prototype development and testing of the controls architecture, software, and hardware components of the tracking and positioning system. PNNL will provide support during both project phases for prototype development and testing of the controls architecture, software, and hardware components of the tracking and positioning system. This effort represents PNNL’s first opportunity to support the floating solar photovoltaics (FPV) industry with capabilities, facilities, and personnel developed to contribute to the marine energy (e.g., wave and tidal energy) sector. This portfolio expansion leverages internal and DOE EERE investments and the growing visibility of PNNL-Sequim’s Marine and Coastal Research Laboratory (MCRL) and our marine research capabilities, in general. The development of effective and low-cost FPV platforms is a potential way to increase the nation’s set of tools for providing emission-free electricity without utilizing valuable terrestrial resources. Successful commercialization of such a project may lead to economic benefits through job creation, supply chain creation, and access to a cheaper source of electricity.

Utility-class autonomous surface vehicles (ASVs) are small watercraft that can be equipped with environmental sensors used to collect data in coastal and marine locations. Their operation is constrained by energy storage limits, but with adequate resources, marine energy presents an opportunity to provide power in remote locations. To demonstrate the feasibility of using tidal energy to support ASV operations, we created a MATLAB-Simulink modeling tool. The model simulates an ASV performing surveys and charging at a nearby tidal turbine. Model components include the tidal turbine, generator, battery storage dynamics, ASV kinetics, and ASV control schemes. We refined the tool using experimentally collected data in the tidal-resource-rich Sequim Bay, which has been proposed for tidal energy testing, to empirically identify vehicle hydrodynamic drag and inertial coefficients. We then used the model to simulate a resource characterization survey in Sequim Bay under varying environmental conditions and survey parameters. Results indicated that a tidal turbine can support continuous ASV operation in low tidal or low target survey speed scenarios, and we suggest improvements to the model.

Wave energy is a vast and largely untapped resource with the potential to contribute significantly to global energy production. A new wave energy technology has been developed by an Australian company, Wave Swell Energy Ltd., consisting of a unique unidirectional axial turbine version of the well-established oscillating water column (OWC) concept. A full-scale prototype of the technology, the UniWave200, was deployed for grid-connected testing near the coastline of King Island, Tasmania, from 2021 to 2022. Data collected during the pilot project were analyzed by the US Department of Energy's Pacific Northwest National Laboratory (PNNL). The results of this analysis indicate the full-process wave-to-grid energy conversion efficiency, based on the combined capture width ratio (CWR) and power take-off (PTO) efficiency, to be on the order of 45$\%$ for significant wave heights above 1 m.

Oceanographic measurement buoys are power constrained by the capacity of their batteries and the available solar power. Many buoys are in locations with abundant wave energy, but wave energy converters are not being used to power them. One reason wave energy converters may not have not been developed for wave measurement buoys is that many buoys measure waves by precisely following the wave motion. Wave energy converters may inhibit this wave-following ability by altering a buoy's response to incoming waves. In this report, we present the results of field tests that measured the extent to which buoy motion was changed by modifications to the buoy for wave energy harvesting. The motion of the buoy was significantly modified by the addition of the hardware components necessary for harvesting wave energy. The ratio of the mass of the wave energy converter to the mass of the buoy was high for the system tested, which strongly affected buoy motion. A lower value for this ratio would decrease the effect of the wave energy converter on the motion of the buoy, thereby decreasing the impact on the buoy's ability to measure waves but also decreasing the power production capabilities. Therefore, the use of wave energy converters to power wave measurement buoys may be feasible for large buoys that measure low-frequency waves and have low power requirements.

Energy systems generating power from ocean waves, currents, tides, and thermal and salinity gradients are being developed to power oceanographic |

A better understanding of carbon cycling dynamics in coastal ecosystems is critical to quantify “blue carbon” storage. However, obtaining the necessary measurements is complicated due to the dynamic conditions that characterize these ecosystems, and requires both spatially and temporally resolved measurements of carbon dioxide concentrations and complementary water quality parameters. In this study, we evaluate the use of a utility-class autonomous surface vehicle as a platform for measuring carbon dioxide dynamics in a shallow, intertidal, blue carbon ecosystem. We integrated a carbon dioxide sensor, a water quality sonde, and hydroacoustic sensors with an autonomous surface vehicle and performed measurements in and around a meadow of Zostera marina eelgrass. Results demonstrate the utility of this system to provide insight into complex carbon cycling dynamics in and around a shallow, intertidal blue carbon habitat.

Unknowns around the environmental effects of marine renewable energy have slowed the deployment of this emerging technology worldwide. Established testing methods are necessary to safely permit and develop marine energy devices. Magnetic fields are one potential cause of environmental effects and are created when electricity is generated and transmitted to shore. Further, the existing variation of the background magnetic field at sites that may be developed for marine energy is largely unknown, making it difficult to assess how much additional stress or impact the anthropogenic magnetic field may have. This study investigates two instruments for their ability to characterize the background magnetic fields at a potential marine energy site in Sequim Bay, WA. Based on this evaluation, this study recommends an Overhauser magnetomer for assessing the background magnetic field and demonstrates the use of this sensor at a potential marine energy site.