ESL’s Ocean Energy Power Systems Provide Alternatives to Batteries, Solar Power

Electro Standards Laboratories (ESL), Cranston, RI, has extended the science in Ocean Wave Energy Harvesting Systems. The company is addressing the need for extended operation of autonomous sensor buoys and other remote ocean platforms.

Many existing remote ocean-based platforms are powered by batteries or by batteries in combination with solar power. Power harvesting from ambient ocean wave energy is a natural and viable option to augment or replace any of these electrical-power-providing systems deployed in the ocean environment.

Electro Standards Laboratories in collaboration with the University of Rhode Island (URI) has produced two concept designs to address these needs, a Direct Drive System and a Resonant Drive System. This technology employs small electric generators that are either directly driven or resonantly driven via a surface buoy’s wave-induced heave motion. Both configurations provide reliable operation without the need for additional gearing and have the ability to harness electrical power in the 1 to 10 Watt range in small sea states.

The Direct Drive System provides power from the differential motion between the buoy float and a submerged resistant plate. The buoy response in the Direct Drive System is designed to match a wide range of expected ocean wave spectra based on the deployment location. Direct Drive of the system with wave motion results in broad band response with high efficiency. Other benefits of this system include low acoustic noise and stealthy operation.

The Resonant Drive System amplifies the generator’s armature motion at the peak period of the sea state. The buoy response in the Resonant Drive System is designed to match the expected ocean wave spectrum based on the deployment location. The benefits of the resonant system include enhanced functionality, higher performance and continuous operation. The buoy is completely sealed with no external moving parts.

Scale model testing has been performed in the URI Department of Ocean Engineering wave tank as well as at the mouth of Rhode Island’s Narragansett Bay. Electro Standards’ model simulations have shown good agreement with the scale model tests. This small buoy sensor system generates and accumulates energy that can be used to indefinitely power remote buoys equipped with sensor arrays as well as electronics for processing and communications. This power source can be used to minimize the size of batteries, or to eliminate the need for batteries if supercapacitors are used. The buoy system design is customized and scalable (1-250 W) and can be suited to moored or drifting applications.

As a result of the success of their Ocean Wave Energy Harvesting programs, the company is seeking organizations with applications for this technology, or with an interest in furthering this scientific study, or who are interested in commercializing this technology. Targeted applications for this technology include: recharging stations for unmanned underwater vehicles, replacement or augmentation for solar power, elimination of batteries, sonar listening stations, weather monitoring buoys, wave monitoring buoys, tsunami warning stations, and port monitoring buoys. Dr. Raymond Sepe, Jr., is the program’s lead scientist.

Press release, March 26, 2014; Image: ESL