Wave Energy Harnessing Device appears promising
Brent Caruso
Issue date: 5/1/09 Section: Campus News
Here at Stevens a new type of renewable energy is in the works. Michael Raftery has been leading the research and development of what he calls the Wave Energy Harnessing Device (WEHD). This system of submerged platforms and buoys will utilize a wave's motion to create electricity. Waves created will cause the buoys, which rest on the surface of the water, to rise and fall. The motion of the buoys is transferred to winches attached to submerged platforms and through a complex system converts this wave motion into electricity. Raftery felt a need for a submerged platform as he explained, "The submerged platform keeps the expensive energy harnessing parts safe from large waves."
The WEHD has been in the works since 2004, and Raftery created a few working scale models recently to test his theory. The last prototype was created in November 2007 and Raftery has spent the past fifteen months working on his new design. Raftery expects to have a 1:10 scale model ready for testing in 2010. "If the test meets our design goals, we plan to build and test a 1:2 scale model by 2012," Raftery explained in an e-mail correspondence.
Wave energy conversion has been attempted before, but Raftery has taken a different approach. His last prototype had problems with variable waves and energy conversion. Raftery and his team have modified their system to allow for variable springs. By changing the springs in their system, they can more efficiently harness the wave energy to maximize the wave motion the system can capture.
Another innovation the team has implemented is wave tuning or "shoaling." Shoaling is a fluid dynamic phenomenon where surface waves on a layer of water of decreasing depth will change their wave height. This is mainly because wave-energy transport velocity will change with water depth. By implementing this design change, Raftery and his team are able to increase the energy density being fed into their system.
Raftery and his team also experienced problems with power output. The last model created could not run the generator attached to the system at maximum capacity because of the low wave frequency. To deal with this issue in the new design, a system known as continuous load control is being implemented. This system will store the energy in a proprietary system before it is converted. This will help eliminate drops in power output between waves to allow a more stable flow of energy.
Raftery and his team currently have patents pending for the variable spring, shoaling modification and the decoupled energy extraction processes that are being implemented in the WEHD. According to Raftery, these methods of energy conversion have never been attempted, according to the existing U.S. and international patents.
If successful, this system could be effective at utilizing energy in moderate wave regions such as the Atlantic ocean from Maine to Florida over the Continental Shelf. In a world that has started taking a more proactive approach to reducing "carbon footprints" and being more environmentally friendly, this alternative energy source could become a new and useful form of renewable energy.
The WEHD has been in the works since 2004, and Raftery created a few working scale models recently to test his theory. The last prototype was created in November 2007 and Raftery has spent the past fifteen months working on his new design. Raftery expects to have a 1:10 scale model ready for testing in 2010. "If the test meets our design goals, we plan to build and test a 1:2 scale model by 2012," Raftery explained in an e-mail correspondence.
Wave energy conversion has been attempted before, but Raftery has taken a different approach. His last prototype had problems with variable waves and energy conversion. Raftery and his team have modified their system to allow for variable springs. By changing the springs in their system, they can more efficiently harness the wave energy to maximize the wave motion the system can capture.
Another innovation the team has implemented is wave tuning or "shoaling." Shoaling is a fluid dynamic phenomenon where surface waves on a layer of water of decreasing depth will change their wave height. This is mainly because wave-energy transport velocity will change with water depth. By implementing this design change, Raftery and his team are able to increase the energy density being fed into their system.
Raftery and his team also experienced problems with power output. The last model created could not run the generator attached to the system at maximum capacity because of the low wave frequency. To deal with this issue in the new design, a system known as continuous load control is being implemented. This system will store the energy in a proprietary system before it is converted. This will help eliminate drops in power output between waves to allow a more stable flow of energy.
Raftery and his team currently have patents pending for the variable spring, shoaling modification and the decoupled energy extraction processes that are being implemented in the WEHD. According to Raftery, these methods of energy conversion have never been attempted, according to the existing U.S. and international patents.
If successful, this system could be effective at utilizing energy in moderate wave regions such as the Atlantic ocean from Maine to Florida over the Continental Shelf. In a world that has started taking a more proactive approach to reducing "carbon footprints" and being more environmentally friendly, this alternative energy source could become a new and useful form of renewable energy.