Page 147 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

Wave Energy Chapter | 5 137

FIG. 5.16 Mean winter (December-January-February) wave power averaged over the NW
European shelf seas plotted against the DJF NAO. The dashed line is the least squares line of best fit
2
(r = 0.69). (Reproduced from S.P. Neill, M.R. Hashemi, Wave power variability over the northwest
European shelf seas, Appl. Energy 106 (2013) 31–46, with permission from Elsevier.)

cannot be used to infer winter wave conditions due to strong seasonal trends in
wave conditions. Although it is important to have local measurements of waves
to characterize the resource, in many circumstances it is more usual for limited
wave buoy observations to be used to validate a numerical model. The numerical
model can then be used to assess the wave resource over much longer timescales.

5.5.1 Theoretical, Technical, and Practical Resources
A wave resource assessment of the type presented in the previous section is
what is known as a ‘theoretical resource’ assessment. A theoretical resource
assessment estimates the annual average energy production for a specific wave
(or tidal) resource, and is generally based on numerical modelling, with limited
validation from historical data records. By contrast, the ‘technical’ resource
is defined as the portion of the theoretical resource that can be captured
using a specified technology. It therefore includes device characteristics (e.g.
efficiency) and constraints such as interdevice spacings. The calculation of the