Deck 14: Ocean Thermal Energy Conversion and Ocean Salinity Gradient Energy

Question 1

Compare the osmotic power available from freshwater flowing at a rate of

Answer 1

For a total osmotic power of 1

Question 2

An offshore OTEC facility operates with a warm reservoir temperature of

Answer 2

efficiency is

Question 3

(a) Calculate the energy available when a 106 kg parcel of water is cooled

Answer 3

Using the values

Question 4

Calculate the average thermal power that is available during that time.

Question 5

A 20 MWe OTEC facility operates at a thermal efficiency of 2.4%. The

Question 6

It has been speculated that an OTEC facility could use wave energy to offset
its low efficiency by providing electrical energy for operating the plant. Where would the
most advantageous location(s) be for such a facility? If the facility could intercept 200 m
of wave front for your chosen location and had a total output of 100 MWe, what fraction of
this total output would be from waves? Assume the efficiency of wave-generated
electricity to be 35%.

Question 7

The Amazon River has a flow rate of

Question 8

Consider the possible design of an OTEC facility that has an electrical

Question 9

An OTEC facility has a total flow rate of water from the deep ocean is at 5°C. During the year the surface water temperature varies
from 19°C to 22°C. Plot the output as a function of warm water temperature over this
range.

Question 10

Question 11

The salinity (mostly NaCl) in some parts of the Great Salt Lake (Utah) is

Question 12

(a) Calculate the gravitational potential energy associated with

Question 13

If the temperature drops across the evaporator and condenser of an OTEC
system are equal, prove that the relative temperature drops as given in equation (14.4) will
maximize the power output.

Question 14

Estimate the salinity of the Dead Sea from the information in this chapter.

Question 15

Consider the experiment of Jean-Antoine Nollet as described in the text,
which illustrates the osmotic pressure between water and wine. Assume wine is 12% (by
volume) of ethanol in water, and estimate, as in Example 14.4, the height of a column of
water that the osmotic pressure between water and wine can support. Note that the van 't
Hoff factor depends on the nature of the solvent and that a value of i ≈ 1.0 is appropriate
for ethanol in water.

Question 16

In the Arctic, winter air temperatures can average around

Question 17

Make a plot of the height of a column of water (in meters) that the osmotic

Question 18

The Mississippi River, the largest of all rivers in the United States, has a

Question 19

An ideal OTEC system has a flow