Modular and Scalable Small-Scale Mass-on-Spring Wave Energy Convertor (MOSWEC) PowerBuoy System for Reliable Powering of Autonomous Ocean Monitoring Systems

Ocean Power Technologies (OPT) has identified a large market for offshore marine renewable systems that can provide power to topside sensors and/or seafloor equipment for various ocean observing and subsea power applications. Existing wave energy converter (WEC) systems have various shortcomings that present barriers to entry for many offshore power markets, such as cost, reliability, and scalability to support the wide range of power demands across different applications. OPT has developed a concept for a Mass-on-Spring Wave Energy Converter (MOSWEC) which overcomes the shortcomings of existing WECs. The MOSWEC “power module” utilizes a mass-spring oscillator (MSO) housed in an airtight compartment near the bottom of the buoy which can be incorporated into a stand-alone PowerBuoy® by adding a flotation collar around the top, coupled to other MOSWEC power modules to form a larger PowerBuoy®, or scaled up for larger power. All moving parts are isolated from external elements. A buoy using the MOSWEC approach can be much shorter than many other WEC buoys, resulting in lower structural loads, simpler moorings and umbilicals, and simpler launch and recovery operations. The design is inherently modular and scalable, allowing it to address varying power demands across different applications. In the Phase I study, OPT completed conceptual design of the MOSWEC system and analyzed various design configurations to verify estimated power levels of different modular and scaled approaches. A base building block with a 3-tonne reaction mass was developed that is estimated to achieve an average peak power of 2 kW, with different configurations providing power levels up to nearly 30 kW. In addition, two main applications were evaluated for technical and commercial feasibility – integration of a subsea AUV docking station and a topside sensor payload for maritime domain awareness. While both applications were confirmed to be technically feasible, the topside monitoring payload for maritime domain awareness was found to have more near term commercial viability. Development of the MOSWEC technology is anticipated to accelerate market adoption of WECs in several applications, reducing the need for crewed vessel patrols and displacing carbon-emitting sources for subsea power applications. For Phase II, OPT proposes to complete detail design, build, and ocean testing of the initial prototype with a 3-tonne reaction mass, referred to as the “M3” MOSWEC. The M3 prototype will be deployed with a topside payload consisting of radar, camera, and AIS to serve as an offshore vessel monitoring system that has applications in defense and security, monitoring of illegal fishing and marine protected areas, enforcement of safety exclusion zones for offshore construction, and tracking vessels traffic in ports or shipping routes.