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The search for renewable energy sources has led to new developments. One such development is the PowerBuoy by Ocean Power Technologies. This paper provides a description of the PowerBuoy technology, detailing how it functions and its advantages over diesel generator power sources at sea. The PowerBuoy provides energy through harnessing wave energy and converting it to electric energy that is usable both at sea as well as on the mainland through connecting to the power grid.
PowerBuoy is an Ocean Power Technologies device that harvests wave energy. By constantly recharging through the harnessing of wave energy, the powerBuoy provides an uninterrupted power supply. The device, which is used in the ocean, floats in the ocean over a depth of 20 meters to 1,000 meters. The PowerBuoy can supply power to payloads and equipment on the seabed. It also provides real time communication and data transfer to remote facilities on the shore. While the device generates energy through wave activity, it can also operate during periods of extended calm (Ocean Power Technologies, 2017). That is possible because it stores sufficient electric energy to keep it going through such periods. The PowerBuoy converts wave energy to electric power by a direct drive generator. The generator charges an on-board battery pack continuously to provide storage for energy (Patel, 2016). The battery then delivers the power to applications.
Ocean Power Technologies’ PowerBuoy minimizes operational costs. It has a simple deployment and recovery, which leverages vessels in offshore marine operations. The deployment of the PowerBuoy can be on the deck of a vessel or it can be towed to site. It has 3-year maintenance intervals, thereby reducing maintenance costs (Ocean Power Technologies, 2017). The device has a control management system that is self-monitoring. It collects, processes and transmits data, making it possible to have proactive maintenance strategies. That increases operational effectiveness.
The PowerBuoy uses a hydroelectric turbine to generate power. As the waves rise and fall offshore, they make the device move up and down freely. The mechanical stroking due to the up and down movement of the PowerBuoy revolves an electrical generator. The generator produces power that can either be stored on the device or transmitted ashore through power cables that are under water (Ocean Power Technologies, 2017). The power transmission cables can connect the PowerBuoy to the electrical grid while sometimes the PowerBuoy operates autonomously in deep water. The device is capable of weathering extreme wave conditions. As it collects data, it is able to detect large oncoming waves. The sensors on the PowerBuoy help monitor the various subsystems and ocean environment around it. When there is a large wave oncoming, the PowerBuoy is able to lock up and stop producing power until the waves go back to normal. The device is then able to unlock and commence power production and submission to the shore.
Previously, maritime surveillance and monitoring systems relied on diesel generators to provide power at sea. They also required frequent maintenance as well as fuel replenishment. That made it costly to maintain such systems. However, with the development of the autonomous PowerBuoy, some of the maintenance costs of these systems have gone down. The PowerBuoy produces renewable energy, hence there is no need for replenishing fuel for the systems. The device also requires less maintenance and therefore reduces the maintenance costs. Since the device also collects and transmits real-time data, it makes it easy to monitor and assess the device to determine when maintenance is necessary. The designing and manufacture of the autonomous PowerBuoy was a project under the U.S. Navy’s Littoral Expeditionary Autonomous PowerBuoy program (Quick, 2011). The goal was to aid maritime surveillance as well as coastal security. The device generates power for systems that detect and track vessels, thus aiding in surveillance. While Ocean Power Technologies deployed the autonomous PowerBuoy in 2011, it completed the grid connection of the PowerBuoy in 2010. The equipment on the PowerBuoy enable the National Oceanographic Atmospheric Administration to obtain ocean current mapping data. It also provides data that is useful in Coast Guard search and rescue missions.
The PB3 PowerBuoy is moored to a single point. It measures 8 feet across, 10 feet wide and 15 feet long. It is capable of producing up to 300 W of continuous power and up to 7.2 kW at peak. The peak usually lasts one hour each day. The device has a modular battery with a capacity of 44 kWh, which is scalable to 150 kWh (Patel, 2016). The device charges its battery as it harvests wave energy and converts it to electric power through the direct-drive generator. The device has a metal plate that provides a weight that works with the up and down motion of the waves to move the hydraulic piston in the PowerBuoy, thereby producing electric energy. The meatal plate at the bottom of the PowerBuoy is ten feet wide and 18 feet long. As the waves move up and down, the PowerBuoy moves with it. However, the metal plate remains stationary due to its weight as well as its position deep in the water where the waves are not effective (Monterey Bay Aquarium Research Institute, 2012). The push and pull on the hydraulic piston due to the motion of the PowerBuoy as it moves with the waves turns a hydraulic motor, which turns the electric generator to generate electric energy. Ocean Power technologies continues to research and design enhanced models of the PowerBuoy. The aim is to have model capable of producing up to 15 kW of power during peak (Patel, 2016). The company also continues to tweak its energy storage systems to increase efficiency and storage capacity.
For many years, there have been efforts to replace fuel energy in many areas. Prior to the PowerBuoy, most maritime surveillance and monitoring systems relied on diesel fuel to run generators that provided energy. That was costly, as it required frequent replenishing of the fuel. It also required frequent maintenance. The advent of the PowerBuoy provides a long-lasting solution to the energy requirements of maritime systems. It provides renewable energy and at a lower cost. The device has a three-year maintenance period and constantly collects and transmits data to enable monitoring. The device can generate enough power for use on-board as well as for transmission to the power grid. Its sensors allow it to work even in extreme wave conditions as it locks and unlocks depending on the strength of the waves. As improvements continue, commercialization of wave energy is likely to expand, as the PowerBuoy is likely to feed the power grid with more energy in the future.
- Monterey Bay Aquarium Research Institute, (2012). Floating “Power Buoy” Creates Electricity from Ocean Waves. SciTechDaily, May 14, 2012.
- Ocean Power Technologies, (2017). PB3. Ocean Power technologies.
- Patel, S., (2016). Ocean Power Technologies Deploys Commercial PowerBuoy with Energy Storage. Power Magazine, January 9, 2016.
- Quick, D., (2011). Autonomous Wave Energy PowerBuoy Device Commences Sea Trial. New Atlas, August 23, 2011.