Page 165 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

Other Forms of Ocean Energy Chapter | 6 153

FIG. 6.6 Global distribution of the technical salinity gradient resource. (Data from P. Stenzel,
Potentiale der Osmose zur Erzeugung und Speicherung von Elektrizität (Potential of Osmosis for
Production and Storage of Electricity), vol. 4, LIT Verlag, Münster, 2012.)

TABLE 6.2 Potential for Osmotic Power Production From a Selection of
Major World Rivers
3
Source of Fresh Water Mean Flow Rate (m /s) Power (GW)
Amazon, Brazil 2 × 10 5 20.8
La Plata-Paraná River, Argentina 8 × 10 4 8.32
Congo, Democratic Republic of Congo 5.7 × 10 4 5.93
Yangtze, China 2.2 × 10 4 2.29
Ganges, Bangladesh 2 × 10 4 2.08
Mississippi River, USA 1.8 × 10 4 1.87
Columbia River, USA 7.5 × 10 3 0.78
Notes: The power estimate is based on 10% of each river’s discharge, and a power output of
3
1MW/m per s.
Source: Based on data presented by Helfer and Lemckert [18].

Pressure Retarded Osmosis
In a PRO system, a membrane is used to separate sea water from fresh water.
Sea water is pumped into a pressure exchanger, where the osmotic pressure is
less than that of fresh water. The freshwater flows through a semipermeable