Deck 12: Wave Energy

Question 1

An ocean wave has a velocity of 20 m/s.

Answer 1

Question 2

Hawaii has about 1200 km of coast line and a population of about 1.4

Answer 2

(a) From Table 2.1 the per capita average power consumption in the United

Question 3

The LIMPET wave generating facility in Scotland has a width of 21 m.
Estimate its efficiency.

Answer 3

From the map, the average wave power in Scotland is 70 kW/m. If the LIMPET
device has a width of 21 m then the total average wave power will be

Question 4

The average wave power available in Hawaii (Figure 12.1) is 100 kW/m.
For waves with a period of 10 s, what is the average wave height?

Question 5

A tsunami in deep water has a period of (a) What is its velocity?
(b) What is its wavelength?
(c) If the tsunami has a height of 2.5 m, what is its power per km of wave front?

Question 6

An ocean wave has a period of 10 s and a height of 2 m in deep water.

Question 7

An ocean wave has a height of 2.5 m and a period of 10 s. What is the total
power available from 20 m of wave front for this wave?

Question 8

In deepwater, tsunamis have a relatively small height (typically 2 m) and a
very long period (typically 30 minutes). The amplitude becomes larger as they pile up
when they reach shallow water. For a tsunami in deep water, calculate the energy per meter
of wave front (in J/m). Compare this with the energy per meter of width of a 2-m wide,
1500-kg automobile traveling at 120 km/h. This comparison emphasizes the damage that
can be caused by a tsunami.

Question 9

A seiche is a standing wave that occurs due to resonant conditions on the
surface of lakes and enclosed ocean bays. It is the result of surface perturbations caused by
phenomena such as seismic activities or weather conditions. The period of a seiche is
approximated by the expression

Question 10

A small boat with two occupants and a 15 kW outboard motor (total mass =

Question 11

An ocean wave has a wavelength of 120 m and a period of 16 s.
(a) Calculate the wave's velocity.
(b) If the amplitude of the wave is 1.5 m, calculate the energy per km of wave front in one
period.

Question 12

An ocean wave has a velocity of 8.5 m/s. What are its period and
wavelength?

Question 13

If a tsunami in deep water has a period of 10 minutes, what would the

Question 14

Most of Greenland's electricity comes from hydroelectric facilities. These

Question 15

North Carolina has some of the highest average wave energies in the United
States along its roughly 500 km of coastline (Figure 12.1). Would it be reasonable for
North Carolina to utilize wave energy for all of its electricity? Assume that a total annual
per-capita electricity requirement of 15 MWhe and that 5% of the coastline is used for
wave electricity generation at an average efficiency of 20%.

Question 16

In a storm, waves may have a height of 12 m and a period of 15 s. Compare
the power per meter of wave front to the average values shown in Figure 12.1.

Question 17

A section of ocean shoreline has incident waves with a constant period of

Question 18

An ocean wave has a height of 5 m and a period of 12 s.
(a) Calculate the wavelength of this wave.
(b) Calculate the power per unit wave front for this wave.
(c) Calculate the energy per unit wave front for one period of this wave.

Question 19

(a) If all other factors are the same, which is the single most important
parameter in maximizing the energy per unit length of wave front for one period of the
wave: wavelength, wave height or wave velocity.?
(b) What is the effect of doubling each of these parameters on the wave energy per period?