Burning fossil fuels, such as coal, generates most of the world’s electricity. Plants that grew millions of years ago slowly changed to form coal. Coal resources are finite. The coal is ground to a fine powder and burned in a furnace. Water flows through tubes inside the furnace, which produces high-pressure steam. The high-pressure steam turns the turbine. This creates electricity.

Finite: Limited, or could be all used up some time in the future.

A wind turbine has rotating blades, which harness the wind's kinetic energy to produce electricity in a generator. Wind power is considered a renewable resource.

Kinetic: Energy coming from things as they move.

The sun’s rays are a powerful source of energy. Solar power stations use hundreds of photovoltaic panels to transform the energy of sunlight into electricity. Like wind power, solar power is considered a renewable energy resource.

Photovoltaic: Producing electric energy from specially treated chemical layers.

Schools going solar: www.irecusa.org/schools/index.html

The heart of a nuclear power plant station is the reactor. Uranium and plutonium are used in nuclear power plants to generate energy. Heat is generated by fission. The heat is used to generate steam. The rest of the process operates the same way as a fossil plant.

Fission: Splitting atoms into two or more parts, which results in the release of large amounts of heat energy.

Fuel cells were first put to practical use in the 1960s in the U.S. space program. They were used to produce electricity and water on the Gemini and Apollo missions. More recent applications include production of electricity for buildings and powering motor vehicles. Any fuel containing hydrogen such as alcohol, natural gas and even gasoline could be used to run a fuel cell. Because fuel cells involve a chemical process different from combustion, unwanted environmental pollutants are not produced.

Fuel Cell: A device that converts chemical energy directly into electrical energy without burning a fossil fuel. The only waste products are water and carbon dioxide.

A hydroelectric power station utilizes water to power a turbine. The turbines are connected to generators that produce energy. Hydroelectric power is a renewable energy source. Today hydroelectric power generates 20 percent of the world’s electricity.

Turbine: A form of a motor that is driven by water, steam or air that has been forced against angled blades. Toy pinwheels, airplane propellers and jet engines are examples of turbines.

Biomass is a plant material, such as trees, wood waste and agricultural residues. Biomass has stored solar energy that can be converted to fuel for the generation of electricity through combustion. Biomass is considered a renewable power source.

Combustion: Burning a fuel such as coal or oil to release its heat energy.