An Evaluation of the U.S. Department of Energy's Marine and Hydrokinetic Resource Assessments (2013) / Chapter Skim
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4 Ocean Current Resource Assessment
4 Ocean Current Resource Assessment
Pages 48-55
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From page 48... ...
Nonetheless, turbines in strong currents might be able to provide significant amounts of power in some locations. A single submerged turbine placed in an ocean current with a swept area A in water with density r and a current of speed v can produce power up to the Lanchester-Betz limit of 0.3rAv3.1 For example, if A is 1,000 m2 and v is 2 m/s, the power calculated is 2.4 MW.
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From page 49... ...
Gunawan, Oak Ridge National Laboratory, "Assessment of energy production potential from ocean currents along the United States coastline," Presentation to the committee on September 27, 2011.
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From page 50... ...
, and NCOM (Navy Coastal Ocean Model) .7 HYCOM-GLOBAL is a real-time 1/12-degree global nowcast/ forecast ocean circulation model maintained by the Naval Research Laboratory8 and sponsored by the National Ocean Partnership Program, while HYCOM-GOM is a regional model with grid resolution of 1/25 degree nested within the HYCOM-GLOBAL model.
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From page 51... ...
. The GIS database was developed using ArcView GIS software that allows for downloading model results for further analysis, such as GIS layers of the monthly and yearly means, standard deviations9 and power densities, probability distributions for current speed and direction, and the effective power using a specified number of turbines, efficiencies, and dimensions.
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From page 52... ...
This assumption fails when Pk becomes large as the turbine size and density increase, causing Pk to overestimate the technical resource. Validation The validation for the ocean current resource assessment was conducted for the Florida Strait region with a very limited data set for HF radar (184 days)
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From page 53... ...
The technical resource will be less than the theoretical resource, possibly considerably less, because of factors that include wake losses and drag on supporting structures. Furthermore, this estimate does not allow for a reduction of the incident flow due to the impact of a large turbine farm on the larger-scale regional flow.
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From page 54... ...
The ocean current assessment group should properly account for back effects by simulating total extractable energy using three- imensional numerical models that include representation of d turbine arrays. The committee also believes that the assessment group needs to further explore and discuss the effects of meandering and seasonal variability of the Florida Current on the extractable power estimate, as the current shows strong meandering and seasonal variability at various frequencies (Johns and Schott, 1987; Lee et al., 1995)
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From page 55... ...
Given that observation in the region of the Florida Current is very limited, a comprehensive field observation with focus on the Florida Current is necessary in the future. Additionally, the ocean current validation was conducted with a very limited data set and could be substantially strengthened by including more existing data for comparison with model results.
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