When the surf’s up on the New Jersey coast, U.S. Navy officials are stoked. The waves are helping the Navy harness the power of the ocean to generate electricity for a sea-based radar and communications system that supports maritime security operations.
The Navy and Ocean Power Technologies Inc. recently completed successful testing of an autonomous buoy, called the PowerBuoy, (similar to one tested off the coast of Oahu, Hawaii, pictured above). The PowerBuoy taps the almost constant wave action on the ocean’s surface to produce the electricity that runs an on-board radar and communications payload.
During a three-month pilot period beginning last August, the PowerBuoy was deployed about 25 miles off the New Jersey coast. It consistently surpassed the Navy’s specifications, which called for a payload power delivery on a continuing basis of 150 watts–enough juice to run the radar and communications system.
The actual results were considerably better than expected as the PowerBuoy supplied continuous power in excess of 400 watts over the three-months at sea.
It was a very great success for us–not just the power performance but its survivability in very extreme wave conditions.”
The PowerBuoy also met the Navy’s requirements for durability in severe weather and wave conditions. It even survived the pounding of 50-foot plus waves during Hurricane Irene last August without damage, said Charles Dunleavy, chief executive officer of Ocean Power Technologies, which has corporate offices in Pennington, N.J., and Warwick, United Kingdom.
“It was a very great success for us on a number of counts, not just the power performance but its survivability in very extreme wave conditions,” Dunleavy told AOL Government.
The PowerBuoy also was designed to furnish power when the waves are flat. Using a proprietary power-management and battery-storage system, the device can provide the requisite power load for up to 30 days without waves.
But it would be exceedingly unusual for the backup system to have to operate for that long. “You can have no-wave conditions but generally for much shorter periods than 30 days,” Dunleavy said.
“In the power-generation mode, [the system] can generate power in extremely low waves–about a foot, and that’s very trivial in terms of wave height.,” he said.
The PowerBuoy was developed under a 2010 contract from the Navy’s Littoral Expeditionary Autonomous PowerBuoy (LEAP) program for coastal security and maritime surveillance. “The idea is to detect all manner of incoming ships or hulls on the surface of the ocean, get that data by radar and then communicate that information to shore via satellite,” Dunleavy said.
Ocean Power Technologies collaborated on the project with the Institute of Marine and Coastal Studies at Rutgers University, which supplied the radar network, and Mikros Systems Corp, which delivered the communications technology.
Dunleavy said LEAP officials decided to deploy a wave-powered buoy to help meet the Navy’s renewable-energy goals but also to reduce the costs of power production and maintenance.
At present, buoy systems requiring remote power at sea are often powered by diesel generators, which need frequent maintenance and refueling. In contrast, the PowerBuoy system has been engineered to require no maintenance for three years.
After testing in the ocean, the Navy’s PowerBuoy was brought back to shore for comprehensive inspection. But it will re-deployed on a more permanent basis “within a few months,” Dunleavy said.