Electricity: How It Is Produced

The basic process of creating electricity is the same, regardless of the power source. A turbine is a wheel or cylinder with paddles or blades arrayed around its circumference. Its purpose is to convert the kinetic energy of a moving fluid or gas into mechanical power. There are a number of ways to get a turbine to spin. When you blow on a pinwheel, you are making a turbine spin.

From STEAM

Most steam-electric power plants burn fossil fuels--oil, natural gas or coal--to change water into steam. Some are using the atom, whereby the fuel-burning furnace is replaced with a nuclear reactor. Splitting of atoms in the reactor creates the necessary heat. Otherwise, nuclear and fossil fuel plants operate in the same manner. Three of Dairyland's four generating stations are coal-fired steam plants.

Fossil Fuels

Fuel is burned in the boiler. Water, circulating through the boiler, absorbs the heat and changes to steam. Pressure of steam against the turbine blades spins the shaft. This turns the generator, which produces electricity. Used steam, cooled by the condenser, is changed back into water for reuse in the boiler. Cool water to condense the steam is drawn from the river or bay where the plant is located. Electricity then goes to a transformer, which raises the voltage for transmission.

Nuclear

Heat is created by controlled fission of nuclear fuel in the reactor. Water, under pressure to prevent it from boiling, is circulated through the reactor, removing heat. Heated water leaves the reactor and passes to the steam generator. Here, the water from the reactor gives up heat to a second separate system where water, not under as much pressure, does boil, producing steam. Pressure of the steam turns the turbine and, from this point, the nuclear plant operates the same as a conventional plant.

From COMBUSTION GASES

Gas turbine burns either natural gas or low-sulfur oil. Air is compressed and discharged into combustion chambers. Fuel is added, mixed with air and burned. High pressure combustion gases are formed and flow to the turbine. Pressure rotates the turbine which turns an electric generator.

From WATER

Millions of tons of water are needed to run a hydroelectric plant. Water, which is held in a reservoir or lake behind a dam, must be higher than the power plant so it can fall with enough force to turn the huge steel blades of the turbine. From the reservoir, water plunges down through large gates or a long pipe (penstock) to the turbine. The spinning turbine drives the shaft which turns the generator, producing electricity. Dairyland owns the Flambeau Hydroelectric Station at Ladysmith, Wis.

How is electricity delivered from the Power Plant to you?

Electricity begins its journey at the generator where it is produced. It then travels to a transformer where the low voltage is changed to high voltage. The voltage can reach levels of over 500,000 volts. Voltage must be increased so that the electric current has the "push" it needs to travel the long distances from the power plant, where it is produced, to the places where it is needed.

Transmission Lines

The high voltage electric current travels through thick wires called transmission lines. Tall transmission towers keep the transmission lines high above the ground. Insulators made of glass or porcelain are used to prevent the electricity from leaving the transmission lines and traveling through the transmission towers which could cause damage and injury. Transmission lines carry the electric current from the power plant to where it is needed. A second set of wires is used to carry the current back to the generator. These wires are there because electric current travels in a closed circuit.

High-Voltage Substations

High-voltage substations are places where very high voltages are reduced to lower levels. High-voltage power lines enter and leave the transformer through large insulators. These insulators are used to keep the high voltages away from the metal tank containing the transformer coils. Oil flows around the coils to keep them cool. Factories and other large industrial plants may need high voltage to operate heavy machinery. Medium voltage substations are designed to further reduce the voltage for use in facilities that do not need the higher voltages.

Step-Down Transformers

The electricity now travels from the substations to transformers in your neighborhood. These transformers, called "Step-Down Transformers," lower the voltage still further to make the voltage safe for ordinary use in your home. These step-down transformers are often located at the top of the poles which carry electrical wires or on concrete pads.

Electricity and You Brochure