The Lewis River Hydroelectric Projects - PacifiCorp

Cresap Bay Park—Interpretive sign #1 (Hydroelectric Story)
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Cresap Bay Park
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It’s Raining Fuel!
Merwin, and its neighbor reservoirs Yale and Swift, exist for the sake of
electricity. From the four generating plants along this river comes
hydroelectric energy that powers streetlights and traffic signals, bakes
bread, runs computers, moves public transportation, and much more.
Hydroelectricity is electrical energy that is produced by converting the
energy of moving water to the energy of moving electrons. The process
begins with the sun: the sun’s radiation warms water in oceans, lakes,
rivers, plants, and the soil, and evaporates it into the atmosphere.
Eventually, this water vapor condenses, falls as precipitation, and makes
its way downhill. On its way down, the flowing water’s energy can be
used to generate electrical energy.
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.”
Sidebar:
How, exactly, does moving water translate into moving electrons The
story begins with water poised above a dam, ready to flow downhill. At
the base of the dam is a generating facility. Water from above the dam is
piped to the generator through huge tubes called penstocks.
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.
The spinning turbine turns a rotor, containing an enormous mass of
magnets, inside a stator that contains a stationary ring of tightly-packed
copper coils. Because of the nature of magnetic fields and electrical
conductors, the motion of the magnets creates a changing magnetic field
that induces electrons to change from a positive to negative charge (and
visa versa) within the copper coils. The motion of the electrons creates a
moving electric field within the copper. This moving field is electrical
energy.
Sidebar
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From the generators, electricity passes through step-up transformers which
allow voltage to be increased so the power can pass efficiently through
high-voltage transmission lines. These high-voltage lines, strung from tall
Appendix 1: panel profiles Lewis River Draft I&E Plan page 23