Chapter 16 WATER, WIND, BIOMASS AND GEOTHERMAL ENERGY
Chapter 16 WATER, WIND, BIOMASS AND GEOTHERMAL ENERGY
Chapter 16 WATER, WIND, BIOMASS AND GEOTHERMAL ENERGY
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302 CHAPTER <strong>16</strong><br />
Illustration <strong>16</strong>-3. The average tidal range on the river Rance is 8.4 meters. It has been<br />
reported in the media that its tidal power plant provides about 3.1x10 9 kWh per year (in<br />
the form of energy of the falling water). (a) How much water is used to produce this<br />
quantity of energy? (b) If the plant produces 240 MW(e), calculate its efficiency.<br />
Solution.<br />
(a)<br />
m = E 1<br />
p<br />
g h = 3.1x109 kWh<br />
(10 m ( 3.6x106 J<br />
s 2)(8.4 m) 1 kWh ) (<br />
kg m2<br />
s 2<br />
1 J<br />
) = 1.3x10 14 kg (per year)<br />
(Compare this number with the number given for a hydroelectric power plant in<br />
Illustration <strong>16</strong>-4.)<br />
(b) Efficiency =<br />
Useful energy output<br />
Energy input<br />
=<br />
240 MW 1000 kW<br />
3.1x10 9 kWh (<br />
1 MW ) (8760 h<br />
1 year ) = 68%<br />
year<br />
FIGURE <strong>16</strong>-8. The water cycle. [From “Energy and Problems of a Technical Society,”<br />
J.J. Kraushaar and R.A. Ristinen. © 1988 by Wiley. Reproduced with permission.]