Page 273 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

Optimization Chapter | 9 261

substructure/foundation systems, and smoothing the power output when com-
bining multiple renewable resources [33]. Although one colocated combination
was briefly discussed in Section 9.3.3 (tidal range power plants and tidal stream
arrays), in this section we focus on the colocation of wind and wave arrays.

9.4.1 Combined Wind-Wave Projects

One obvious example where multiple renewable energy resources could be
combined at a single location is wave and offshore wind. The offshore wind
and wave industries face the same hostile marine environment, and face similar
administrative and technological barriers [33]. From a resource perspective,
although wind fields lead to the generation of wind waves, often there will be a
phase difference or a lag between wind power and wave power, for example,
consider the spread of data in Fig. 9.18 calculated for WaveHub, UK. In
particular, swell waves are independent of the local wind climate, and so in many
ways the wind and wave resource are complementary (although optimization
would be required to select the best sites for colocation).
Stoutenburg et al. [35] examined the temporal correlation (Pearson’s)
between wind power and wave power at the same and different wave buoys off
the coast of California (Fig. 9.19). Lower values (i.e. weakly correlated sites)
indicate increased diversity, and so good potential for colocation of wave and

FIG. 9.18 Percentage joint probability of (normalized) wave and wind power at WaveHub, UK.
Wind speed is from the ECMWF ERA-Interim reanalysis dataset, and wave data is from a modified
version of the wave model presented by Neill and Hashemi [34] forced with ERA-Interim data.
Time series analysed is 10 years.