The Lewis River Hydroelectric Projects - PacifiCorp

Lewis River Interpretive & Education Plan
Hydroelectricity is a “renewable” energy source. Water is always being
evaporated by the sun and carried by air currents into the Cascades; it is always
condensing and raining down, re-filling the reservoirs. It has been said that in
the world of hydroelectricity, “it rains fuel.”
History of
Hydroelectricity
As early as the 1880s, just a few years after Thomas Edison demonstrated the
incandescent light, hydroelectric facilities were operating in the eastern United
States. As electric-generation technology improved—and more and more uses
for electricity emerged—public electrification and hydropower operations began
to appear across the continent. In 1889, the first commercial long-distance
electric transmission lines in the world carried power from Willamette Falls
to Portland. In 1891, Ellensburg, Washington inaugurated the first municipal
electric system in the Northwest. By the first decade of the 20th century, plans
were being made to harness the Lewis River to generate hydroelectric power.
Interestingly, at the beginning of the hydroelectric era, hydroelectric generation
did not necessarily mean big dams. Many early hydroelectric plants worked
via waterwheels, which used small dams, or none. But to produce electricity
reliably, steadily, and on a large scale, some large-scale system of water storage is
needed, so flow can be regulated. As dam technology developed, hydroelectric
generation was increasingly incorporated into the structures of larger dams.
However, some of the Northwest’s most massive dams, including the Grand
Coulee (which has a greater generation capacity than any other dam in North
America), were built primarily for agricultural, not hydroelectric, purposes.
Inside a
Hydroelectric Plant
The story of hydroelectric generation begins with water poised above a dam,
ready to flow downhill. This water has potential energy—which can be thought
of as the potential to flow downward and to push against something. At the
base of the dam is a generating facility. The capacity of the water to generate
electricity is related to the height of its surface above the generator; this is called
the hydroelectric head. Water from above the dam is sent to the generator
through huge tubes called penstocks. As the water descends, its potential energy
becomes kinetic energy, or energy of motion.
At the end of each penstock, the rushing water enters a turbine—a device
that resembles a huge propeller or fan. Large louvers called wicket gates allow
operators to closely regulate the rate at which water flows through the turbine.
The water pushes against the blades of the turbine, spinning it at a high rate of
speed and imparting kinetic energy to the turbine itself.
Sea Reach Ltd • 146 NE yamhill Street • Sheridan, OR draft 3 • November 2008 • page 72