RENEWABLE ENERGY COMES from sources that do not become depleted as we use the energy.
When a fossil fuel such as coal is burned, it is gone forever, but a renewable source remains available no matter how much is used. The tides, waves, flowing water, sunlight, and the wind are all renewable sources of energy. Wind and water energy are captured by a 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, but to come together again, the electrons 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 supplies electric current for as long as light keeps falling on it.