Have You Thought About FLOSSing?

Imagine if harnessing renewable energy from the marine environment could one day be as easy as flossing teeth. Is that possible? Maybe!

Many ocean current marine energy systems currently in development are limited to certain applications due to water depths and low flow current speeds. In North Carolina, potential sites for ocean current marine energy device installations typically average flow speeds under 1.5 meters per second (m/s) and can be as low as 0.2 m/s. Fortunately, a team of researchers from North Carolina State University, funded by the North Carolina Renewable Ocean Energy Program, is working to engineer a device suitable for NC’s offshore environment.

Members of the Engineering Mechanics and Space Systems Laboratory, led by Dr. Andre Mazzoleni (pictured speaking left or above), draw inspiration from the simple act of flossing teeth for their latest project. The Flow-powered Low cut in speed Oscillating Subsea System, or FLOSS, is a novel system that utilizes changing drag bodies connected by a cable to rotate a central transmission wheel that interacts with a generator.  When the FLOSS is deployed in moving water, small modifications to the shape of the drag bodies cause the cable to lengthen on one side and thus retract on the other. As the cable slides through the central point of the device, a generator is engaged and produces electrical energy.

So far, small prototypes of the FLOSS have been tested (as pictured below), and previous experiments have shown that this kind of system can operate successfully in low flow speeds of 0.25 m/s, even in shallow, surface-level currents. With the most recent funding from NCROEP, the group is focused on how the device can be used for “trickle-charge” applications, in which a storage battery is given a slow, gradual power supply to maintain long-term battery health and voltage while also preventing the battery from over-charging or extensively discharging.

Additionally, the researchers hope to optimize drag body shapes and tether lengths, continue their evaluation of system efficiency, and further assess the FLOSS’s ability to generate power in low-flow conditions. To meet these goals, the group will:

1. Develop a model that considers hydrodynamics as well as the behavior of the drag bodies, tether, and generator. The model will help refine the system and assess operational and environmental risks, further informing future prototypes and increasing energy capture.
2. Conduct experiments to test drag body designs, generator loading, and tether response. These experiments will also aid in optimizing the system, as well as provide validation for the model referenced above.
3. Evaluate the feasibility of future use and deployment, including considerations for regions of deployment, the necessary resources and expertise needed for successful installation and maintenance of the system, and preliminary estimates for the system’s associated costs. These findings will be compiled into a final report for NCROEP.

“Most recently, we have conducted multiple tests at the NC State free surface water tunnel, including performing a parametric study of various drag body shapes and sizes in low flow to determine the effect of drag body size and shape on the power that can be generated,” shares graduate student Saurabh Agrawal.

The group is also currently working on the design of an open-water, proof-of-concept prototype which will enable them to test a FLOSS system in the Croatan Sound.

The FLOSS is advantageous because, compared to other marine renewable energy devices, it may lower up-front and maintenance costs; produce energy at lower flow speeds; reduce environmental disturbance to the underwater soundscape by minimizing noise usually produced by cavitation and wake; and simplify deployment and maintenance needs. Each of these benefits will help advance NC’s future energy portfolio and enhance economic viability for marine renewable energy extraction in NC.

It is for many of these reasons that Agrawal has liked working on the project. “I have most enjoyed the journey of conceiving and then developing the idea- evolving the FLOSS concept toward a real-world application for powering the blue economy. Given the novel nature of the concept, working to validate the theory and develop new designs has been especially exciting. I am most excited by the potential it holds as an environmentally friendly energy system,” he summarizes.

To learn even more and see the FLOSS in action, watch the video below!

The preceding story first appeared in the Winter 2026 edition of CoastLines, published in January.