An Evaluation of the U.S. Department of Energy's Marine and Hydrokinetic Resource Assessments (2013) / Chapter Skim
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3 Wave Resource Assessment
3 Wave Resource Assessment
Pages 38-47
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From page 38... ...
Because wave energy travels in a particular direction, care must be taken when interpreting maps that show wave power density as a function of location but do not indicate predominant wave directions. It also must be recognized that if the energy is removed by a wave energy device from the wave field at one location, less energy will necessarily be available in the shadow of the extraction device.
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From page 39... ...
, shadowing effects due to actual devices are a topic of active research. The planning of any large-scale deployment of wave energy devices would require sophisticated, site-specific field and modeling analysis of the wave field and the devices' interactions with the wave field.
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From page 40... ...
Compared to the more rigorous approach taken to compute the theoretical resource, the technical resource estimate relies on considerably looser assumptions. In the report, many of the factors are bundled into a single "packing density" of power per kilometer of installed system and some simple assumptions about the range of conditions in which the installed system can operate.
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From page 41... ...
. The committee commented on the work of the assessment group on the basis of these materials and has identified concerns related to the suitability of the hindcast data set in shallow waters, the technique used to generate the aggregate theoretical resource, the lack of directional information, and the technology assumptions utilized for assessment of the total technical resource.
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From page 42... ...
Scalar Power Density A further concern related to the theoretical resource assessment is the use of the unit-circle approach. This approach has the potential to doublecount a portion of the wave energy if the direction of the wave energy flux is not perpendicular to the line of interest or if there is significant wave reflection from the shore.
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From page 43... ...
Recoverable power integrates the fundamental technical constraints based on wave frequency and wave height thresholds, as well as indirectly on the temporal variability, before loss in the mechanical and electrical power transformation. Hypothetical or selected devices are considered operational in given wave periods and significant wave height ranges, specific to the device's characteristics.
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From page 44... ...
. To estimate the fraction of recoverable power at a given point, the assessment group compared the power carried by the incident wave field to the estimated recoverable power assuming a priori a deployment of multiple devices, defined by their combination of rated power and density.
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From page 45... ...
Validation The committee agreed that the assessed estimates of monthly or annual mean wave power were the primary metrics for validation. I naccuracies in these estimates could result from two primary sources of error: (1)
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From page 46... ...
The theoretical wave resource assessment estimates are reasonable, especially for mapping wave power density, although the accepted unitcircle approach overestimates the aggregate total theoretical resource.
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From page 47... ...
. The technical resource assessment is based on loose assumptions about how much average power is available from each kilometer of installed wave-energy conversion facility, indicating that nearly all of the available wave energy in some sites could be converted to electrical energy if enough wave-energy converters are installed.
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