A Buoy-Based WEC Device to Provide Low Power to Sensors

Remote ocean instrumentation and monitoring techniques often rely on floating buoys with a variety of sensors to acquire time series measurements such as ambient noise, acoustic tracking or communications. The operating lifetime of small remote buoys is limited by onboard battery power. Remote acoustic sensors with hydrophone arrays, onboard RF transmitters, GPS receivers and other support electronics can draw up to 100–200W of continuous power in operation, limiting battery life in many cases to 12 to 24 hours between recharge. Recharging is inconvenient, and often impractical to the point that many compact sonobuoys are designed to scuttle themselves after about a day. The associated cost, as well as the environmental impact of sending large amounts of battery and electronic hardware to the bottom of the ocean, is a strong driver for developing renewable ocean power sources for semi-permanent unattended buoy deployments. In support of this vision, a simple, low-cost buoy size platform capable of generating power by scavenging energy from ocean wave motion is developed and demonstrated. The phase 1 prototype is designed to deliver a minimum of 50W of average power from the wave motion characteristics. The motions and the resulting tension in the mooring line are calculated through a linear potential-based computer program. The heaving-body WEC (Wave Energy Converter) design and the modeling are discussed. The design data and the calculations are presented as part of proof of concept of the power generation mechanism and the buoy.