Environmental Engineering Reference
In-Depth Information
Yet, since markets provide opportunities as well as barriers, the market potential may, in
theory, be larger than the economic potential, as the recent boom in renewables shows.
4.2 Hydropower
Water is fluid, soft, and yielding. But water will wear away rock, which is rigid and
cannot yield.
- Lao Tzu
Though presumably unaware of the chemical properties of its molecules, the Chinese
philosopher Lao Tzu (sixth century BCE) understood that water is highly cohesive yet
loosely bound; dense yet fluid. Because water is 800 times denser than air, it is a far more
potent conduit of energy. The most destructive of natural disasters involve water. Even
where the original cause is not hydrological - as in the case of hurricanes or earthquakes -
it is usually the resulting floods or tsunamis that wreak the greatest damage.
The earliest uses of the force of flowing water were to irrigate croplands (waterwheels
numerous improvements over the centuries, there was little substantial change in the way
waterpowerwasharnesseduntilthenineteenth century,whenwaterturbineswereinvented.
A water turbine essentially replaces the millstone in a watermill with a generator. Water
turbines emerged at roughly the same time as steam turbines, and indeed many of the
world's first power stations were driven by water.
From modest beginnings in 1878, when the English industrialist William Armstrong
harnessed flowing water to power a single lamp in his home, hydropower developed
rapidly. Just four years after Armstrong's breakthrough, Thomas Edison, that remarkable
pioneerofallthingselectrical, openeda25-kilowatthydroelectric powerplantinAppleton,
Wisconsin. Over the next two decades, the technology spread rapidly, and throughout
the twentieth century hydropower plants led the way in terms of scale. The Hoover and
Grand Coulee dams, completed in 1936 and 1942 with capacities of 1.4 and 6.8 gigawatts,
respectively, dwarfed contemporary power plants. Even today, the world's largest
greater than the largest fossil fuel or nuclear power plants.
