Environmental Engineering Reference
In-Depth Information
Average montly capacity factor for wave power
50%
45%
40%
35%
30%
25%
20%
15%
10%
Monthly average wave power
Average annual wave power
Monthly average wind power
5%
0%
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Month
Figure 2.22
Average monthly wave power in the UK. Average monthly wind power capacity factor
[15] is shown for reference purposes. (Reproduced from Sinden, G.E., 2007, DPhil Thesis with permis-
sion of Environmental Change Institute, Oxford University Centre for the Environment)
The wave resource, not unlike the wind resource on which it depends, also varies on a
day - to - day and season - by - season basis; in general wave conditions are more energetic in the
winter than in the summer. For example, about half of the annual wave power at all UK sites
occurs during the winter months of December, January and February, as shown in Figure
2.22. This exceptional match between availability and demand for the UK would also hold
for many countries with coastal areas facing the Atlantic or Pacifi c in the northern hemi-
sphere. Figure 2.22 also depicts the seasonal variability of wind to illustrate, by comparison,
the pronounced variability of wave power.
Wave power levels [16] are predictable to varying degrees over different timescales. At
short forecast periods (a few hours), information on the wave conditions offshore, coupled
with the power available from wave devices in the previous hour, can be used to estimate
future output. For longer forecast periods, wave models provide estimates of wave power up
to 5 days ahead.
2.8 Biomass
2.8.1 The Resource
Biomass differs considerably from the other renewable sources in that it takes the form of a
fuel that can be stored and used for electricity generation when required, in the same way as
fossil fuels. However, unlike fossil fuels, biomass is often limited by the energy density of
