Page 269 - Handbook of Energy Engineering Calculations

SECTION 6

HYDROELECTRIC ENERGY POWER PLANTS

Hydroelectric Power-Plant Parameters

SMALL-SCALE “CLEAN ENERgY” HYDRO SITE ANALYSIS

Economic Evaluation of Small-Scale Hydro Sites

Analysis of a Large-Scale Hydroelectric Energy Plant

HYDROELECTRIC POWER-PLANT PARAMETERS

Hydroelectric plants emit zero, or very small, amounts of greenhouse gases.

Thus, hydro plants are an attractive source of power in today’s global-
warming conscious world. But, according to some experts, every major
potential hydro site has been developed; i.e., a hydro plant has been built on
the site. The result? Small hydro sites have become very popular, worldwide.

Hydro power is inherently efficient. Efficiencies of 80 percent plus are
commonly reported by many hydro plants—both large and small. Thus, a
3
cubic foot per second of water at 62.5 lb/ft falling 8.8 ft is equivalent to 12
hp, and falling 11.8 ft is equivalent to 1 kW.
In selling power from hydro plants, the horsepower-year and kilowatt-year
are sometimes used. At 100 percent load factor, 1 hp-year = 0.746 kW-year =
8760 hp-h = 6540 kWh. The power output of any hydro plant is limited by
the installed equipment, the available water supply, the head available, and

the storage quantity if the plant has pumped-storage facilities. *
Pumped storage is the most widely used energy storage system in the

world today. The key to pumped storage is a reversible pump-turbine that can
act as a pump during low-energy-demand hours and as a turbine during high-
energy-demand hours. Some older hydro stations use separate pumps and