INTRODUCTION The roar of a waterfall suggests suggests the power of water Rampaging floodwaters can uproot strong trees and twist railroad railroad tracks When the power of water is harnessed however it can do useful work for humans Since ancient times people have put the energy in the flow of water to work They first made water work for them with the waterwheel a wheel with paddles around its rim Flowing water rotated the waterwheel waterwheel which in turn ran machinery that was linked to it Today new kinds of waterwheels known as turbines spin generators that produce electricity Electricity from water-turned generators is known as hydroelectricity By building a dam across a river the natural upstream water level is elevated and a difference 4
These turbines produce electricity at the Grand Coulee Powerplant in Grand Coulee Washington 5
HYDROELECTRICITY in head is created that can be used to drive turbines and generate electricity A large upstream reservoir may balance seasonal water flow rain or melted snow can be stored in the reservoir during the wet season to provide electricity during dry seasons Small run of river reservoirs or ponds are not large enough to provide seasonal balance They can however provide extra power during daily peak hours In most communities electric-power demand varies considerably at different times of the day To even the load on the generators pumped-storage hydroelectric stations are occasionally built During off-peak periods some of the extra power available is supplied to the generator operating as a motor driving the turbine to pump water into an elevated reservoir Then during periods of peak demand the water is allowed to flow down again through the turbine turbine to generate electrical energy Pumped-storage systems are efficient and provide an economical way to meet peak loads Waterpower is distributed unevenly among the continents and nations of the world Europe and North America have developed much of their waterpower waterpower Asia South America and Africa have abundant abundant waterpower potential but while countries such as China and Brazil have become leading hydroelectric 6
INTRODUCTION The Grand Coulee Dam was built between 1933 and 1941 Its water is used to generate electricity at the Grand Coulee Powerplant hydroelectric producers much of the waterpower resources on those continents remains undeveloped The use of hydropower in the United States has been significant since about 1900 The Columbia River drainage area which is the site of the Grand Coulee Bonneville and Hungry Horse dams has both the greatest potential and the greatest developed developed waterpower California ranks second in the nation in potential waterpower while the Ohio River 7
