Page 606 - Ultimate Visual Dictionary (DK)

THE MODERN WORLD
Renewable energy

RENEWABLE ENERGY COMES from sources that VESTAS V47 WIND TURBINE Blade pitch
do not become depleted as we use the energy. control
When a fossil fuel such as coal is burned, it is
Blade
gone forever, but a renewable source remains
available no matter how much is used. The
Hub controller
tides, waves, flowing water, sunlight, and the
wind are all renewable sources of energy.
Aerodynamic
Wind and water energy are captured by a
hub cover
device called a turbine. The turbine spins and
drives an electricity generator. Energy from
sunlight, or solar energy, is changed into
electricity in two main ways. One uses
mirrors to concentrate solar energy and
magnify its heating effect which is used to
change water into steam to drive turbines.
Photovoltaic cells change sunlight directly
into electricity. A cell is made from two layers
of silicon. One gives out electrons (negative
particles) and the other receives them.
Sunlight knocks electrons out of atoms where
the two layers meet, separating them from
the positive particles. The electrons are
attracted to one layer of the cell, the positive
particles to the other layer. Electrons are
naturally attracted to the positive particles, Blade hub
but to come together again, the electrons Blade bearing
must flow out of the cell, through an external
electric circuit, or load, and back to the other
side of the cell, creating a charge. The cell Rotor lock
supplies electric current for as long as light
keeps falling on it.
Turbine floodgate
opened by winch Main
TIDAL POWER
Road bridge across allows trapped floodgate
an estuary water to flow out closed as
to the open sea tide falls
Open sea
Rising tide
passes through
main floodgate
Winch into estuary
operates
turbine
floodgate

Turbine
floodgate Escaping water
closed, trapping drives turbine
water behind it
RISING TIDE FALLING TIDE

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