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January 2011 Issue
MARIN Tests Offshore Wind Turbines Against Breaking Waves
The Maritime Research Institute Netherlands (MARIN) recently completed a pilot series of tests with a special model of an offshore wind turbine with realistic flexibility, confirming that breaking waves can induce significant oscillations and accelerations in turbines.
"Breaking waves can occur quite often in the shallow-water areas of fixed wind turbines," said Dr. Bas Buchner, vice president of MARIN and leader of its Renewable Energy Team. "Considering the relatively flexible foundations and towers of offshore wind turbines, we realized that the impulsive loading of breaking waves might result in resonant vibrations of the structure. This can have significant effects on the loads in the tower and accelerations in the critical mechanical systems at nacelle level. But we did not want to state this as a problem without confirmation, so we developed these pilot model tests within our internal R&D."
For this purpose, a special model was developed by MARIN's specialists in the field of hydrodynamic loading and structural response. The model material and setup was chosen such that the model had the correct flexibility and natural periods, a technique recently developed to investigate the vibrations of ships in extreme waves.
The initial results of the tests confirm that the tower can vibrate due to the breaking waves.
The test results will now be further analyzed together with MARIN's partner, the Energy Research Centre of the Netherlands (ECN).
"Breaking wave loads can affect the extreme and fatigue loads on the foundation, tower, turbine blades, shaft, gearbox and generator, aspects that have not been studied in detail so far," said Aart van der Pal, manager of integral wind turbine design at ECN. "This will need to be taken into account in the design process."
Together with a number of other partners, MARIN and ECN are in the process of starting up a joint industry project with the acronym WiFi: Wave Impacts on Fixed Turbines. The objective of WiFi will be to develop a design methodology for offshore wind turbines that includes the effect of steep and breaking waves. For more information, visit www.marin.nl.
Severn Tidal Power Project Found Not Currently Feasible
The U.K. government recently published the findings of its Severn Tidal Power Feasibility Study, with the conclusion that it will not approve public funding of a tidal energy project in the Severn estuary at this time.
"The costs and risks for the taxpayer and energy consumer would be excessive compared to other low-carbon energy options," Chris Huhne, secretary of state for energy and climate change, said in a statement regarding the study. "The government believes that other options, such as the expansion of wind energy, carbon capture and storage, and nuclear power, represent a better deal for taxpayers and consumers at this time."
Huhne pointed out that while the Severn's enormous tidal range could provide up to five percent of the nation's current electricity generation, costs would be high. Furthermore, the Severn estuary and some of its tributaries are designated as internationally important nature conservation sites. For more information, visit www.decc.gov.uk.
World's Largest Floating Tidal Power Plant Opens for Trials
Hydra Tidal's (Harstad, Norway) floating tidal power plant Morild II had its official opening ceremony on November 23, marking the start of the planned two-year trial period for testing and verification of the plant and the company's tidal energy generation technology.
The plant has an installed capacity of 1.5 megawatts, and the turbine blades are made of laminated wood with a diameter of 23 meters. Eivind Nydal, chief executive officer of Hydra Tidal, said these factors qualify Morild II as the largest floating power plant of its kind in the world.
After a construction period of about two years, the plant was launched at sea in Harstad this fall and then towed to Gimsoystraumen in Lofoten, where it is now anchored and connected to the local power grid. The Morild II was expected to supply power to the grid by the end of 2010, Hydra Tidal said. For more information, visit www.hydratidal.com.
Lockheed Martin to Continue OTEC Plans in Hawaii
The U.S. Naval Facilities Engineering Command recently awarded Lockheed Martin (Bethesda, Maryland) a $4.4 million contract modification to advance the design for an ocean thermal energy conversion (OTEC) pilot plant off the coast of Hawaii, an addition to a contract issued in 2009.
Under the contract, a Lockheed Martin-led industry team will continue to develop critical system components and designs for a Hawaiian OTEC pilot plant.
"OTEC is an ideal energy generation technology for shoreline communities and military bases in tropical areas, some of which are largely dependent on imported fossil fuels for power and transportation," said Chris Myers, Lockheed Martin vice president for energy and government programs. "We are applying our decades of experience designing and deploying maritime systems for defense markets to ocean power, helping to produce clean energy."
Lockheed Martin's experience with OTEC technology dates back to the 1970s, when the company built Mini-OTEC, an early prototype that remains the world's only floating OTEC system to generate power in excess of what is required for self-sustainment. For more information, visit www.lockheedmartin.com.
GL Garrad Hassan Chosen for SMart Wind's Hornsea Zone
SMart Wind, the consortium led by Mainstream Renewable Power and Siemens Project Ventures, has appointed GL Garrad Hassan (Hamburg, Germany) to act as independent engineer for the first two 500-megawatt projects in the four-gigawatt "Hornsea" zone located off the coast of Yorkshire, England. Last month, the consortium announced that it had secured grid connection for the first two 500-megawatt projects, with first connection earmarked for 2014.
The offshore wind team at GL Garrad Hassan will provide technical assistance for the assessment of structures and analysis of the risk management and layout design processes.
The Hornsea project is scheduled to deliver full power capacity by 2020. For more information, visit www.smartwind.co.uk.
For more information, visit www.marineturbines.com.
2012: JAN | MARCH | MAY | JULY | SEPT | NOV
2011: JAN | MARCH | MAY | JULY | SEPT | NOV