Electric energy

What Is an Electric Generator?

An electric generator is a machine capable of transforming some type of energy into an electric current. The energy source can be very varied: chemical energy, mechanical energy, light energy, or thermal energy.

What is an electric generator?

The mechanisms that perform this energy conversion can include steam turbines, gas turbines, water turbines, internal combustion engines, and even cranks.

Electric generators are electrical devices capable of maintaining a difference in electrical potential (voltage) between two points. That is devices that produce electrical energy.  

The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. Generators provide almost all the energy for electrical grids.

Today, it is possible to buy an electric generator for almost any need

What Are the Types of Electric Generators?

There are different types of electrical generators very different from each other:

  • Mechanical generators that use mechanical energy to produce electricity. They are commonly used in the industry. These generator sets are the most efficient and diversified. Among them, appear the diesel generators or the gasoline-electric generator.

  • Solar generators: it has the ability to transform solar energy into electrical energy. This transformation is carried out by photovoltaic panels that provide a direct current.

  • Thermal generators: they are generators that transform thermal energy into electricity.

  • Chemical generators: convert chemical energy into electrical energy. Examples of this type of generator are batteries.

How Does a Mechanical Electric Generator Work?

The principle of operation of an electric generator is similar to that of an electric motor operating in reverse. They work by electromagnetic induction.

This transformation is achieved by the action of a magnetic field on electrical conductors arranged in coils on a sheet metal framework. If mechanically there is a relative movement between the conductors and the field, an electromotive force is generated. This discovery is the merit of physicist Michael Faraday. This electromotive force generates an electric current.

Mechanical generators can range from small diesel-electric generators to very large machines. Many of the commercial models have a built-in electric starter.

Mechanical energy can be obtained through different means. For example, by means of a heat engine, that is to say, a gasoline or diesel engine. But they are also used in thermoelectric plants in general and in nuclear plants in particular.

One of the techniques used in thermal power plants is to generate steam at high pressure and drive a steam turbine. 

The output power output is usually obtained in alternating current.

Sometimes these types of generators are used to drive water pumps.

How Does Dynamo Work?

The dynamo is the first electric generator capable of producing electricity for industrial needs. Today, it is still the most important generator in use in the 21st century.

 The dynamo uses the principles of electromagnetism to convert mechanical rotation into alternating electrical current. The first dynamo, based on the Faraday principle, was built in 1832 by Hippolytus Pixie. It used a permanent magnet turned by the crank. The rotating magnet is positioned so that the north and south poles pass onto a piece of iron wrapped in wire.

Pixie discovered that the rotating magnet produced a pulse of current in the wire each time one pole passed through the coil. Also, the south and north poles of the magnet induced currents in opposite directions.

By adding a Pixie switch, you can convert AC current to DC.

What Are Thermoelectric Generators?

A thermoelectric generator, TEG (also Seebeck generator) is a device that 

A thermoelectric generator (TEG) is a device that converts temperature difference directly into electricity. In doing so, it uses a thermoelectric phenomenon called the Seebeck effect.

The efficiency of thermoelectric generators is 5-8%.

A thermoelectric generator, unlike ordinary generators, has no moving parts. In some cases, you can use a fan or a pump. TEGs are relatively easy to manufacture but the efficiency is low and the price is high. Greater efficiency requires greater temperature differences.

With technical progress, thermoelectric generators may be used in the automotive industry in the future, where they will use exhaust heat. A heat difference of 700 ° C (~ 1,300 ° F) could generate 500-750 W of electricity.

TEG can work in combination with photovoltaic energy and thus increase the efficiency of the system.

Radioisotope Thermoelectric Generator (RTG)

It is used in spacecraft, where it is known as a radioisotope thermoelectric generator. In the latter, the decay of radioactive fuel is used as a heat source.

However, the principle of operation is different from that of a conventional nuclear reactor.

A radioisotope thermoelectric generator is a simple electrical generator. This type of generator obtains energy from the energy released by the radioactive decay of certain elements.

About 30 radioactive isotopes can be used as fuel. X-rays can be used where photovoltaic energy cannot be used because they are too far from the sun.

RTGs are the most suitable devices in:

  • Situations where there is no human presence,

  • Powers of several hundred watts are needed for long periods of time.

  • Conventional generators like fuel cells or batteries are not economically viable.

  • Places where photovoltaic cells cannot be used to take advantage of solar energy.

An alternative to X-rays could be Stirling engines, which are more efficient but contain moving parts.

How Do Solar Generators Work?

Solar generators work by the so-called photovoltaic effect. Photovoltaic panels are composed of a material that, when hitting a photon, releases an electron. The sum of the electric charges of these electrons forms a continuous electric current.

The most used material in photovoltaic cells is silicon.

Since the output power is in direct current form, it is likely you need to use powered inverters. A power inverter is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC).

With proper technical support, it is easy to install.

How Much Energy Does a Solar Panel Produce?

As an example, if you get 5 hours of direct sunlight per day in a sunny state like California, you can calculate the solar panel output like this:

5 hours x 290 watts (an example of the wattage from a top solar panel) = 1,450 watts, or about 1.5 kilowatt-hours (kwh).

Therefore, each solar panel in your system would produce around 500-550 kWh of energy per year.

What Are Electric Generators Used For?

Electric Power Plant

A power plant is an industrial facility for the generation of electricity. These types of plants use mechanical generators. The current is created by the relative motion between magnetic flux and a conductor.

Power from power plants can be obtained in the following ways:

  • Burned fossil fuels that are most of the world's power plants.

  • Generating nuclear reactions in nuclear power plants.

  • Using renewable energies such as solar, wind, and hydroelectric.

Generators for Vehicles

Generators can be used to power different forms of transportation:

  • Road vehicles. Motor vehicles require electrical energy to power their instrumentation, keep the engine running, and recharge their batteries.

  • Sailing boats can use a water or wind generator to charge the batteries. A small propeller, wind turbine, or impeller connects to a low-power generator to supply currents at typical wind or cruising speeds.

  • Electric scooters. Electric scooters with regenerative braking have become popular all over the world.

Generator Set

A motor-generator is the combination of an electric generator and a motor. Both elements are assembled together to form a single piece of autonomous equipment.

It is customary to use reciprocating piston engines, but there are also those that use gas turbines. Traditionally, this kind of generator is used for many purposes like emergency backup generators.

Generators can be powered by gasoline, diesel, or gas, and even, in some kind of generators, a mix of them. Dual fuel generators use two different types of fuel (most often diesel and natural gas) at the same time. These fuels can be mixed in different proportions or used alone, depending on the engine and the situation.

Human-powered Electric Generators

There are generators whose source of energy comes from the force of human muscles.

Human-powered electric generators are commercially available and have been the project of some DIY enthusiasts. Usually, the principle of operation of these generators is carried out by means of the power of

An average person can produce an average of 75 watts for 8 hours. On the other hand, a first-class athlete could produce roughly 298 watts.

What Is a Home Standby Generator?

An automatic electric generator (or standby generator ) is a standby electric system that operates automatically. In the event of detecting a power outage, a circuit is responsible for turning on the generator and transferring the electrical charge to it. Thus, in a matter of seconds, the electrical circuits become powered by the generator working like an emergency backup.

Once electrical power is restored, the electrical charge is transferred back to it and the generator shuts down.

Generators typically run on diesel, natural gas, or liquid propane.

Automatic electric generators may be necessary to ensure the operation of critical systems, such as fire fighting systems, elevators in tall buildings, or medical equipment for critically ill patients. The use of standby generators in residential areas is also common, in order to provide an electrical reserve for electrical appliances and air conditioning and security systems.

What Is an Inverter Generator?

An inverter generator is an electrical mechanical generator that its speed varies depending on the electrical demand.

Both common portable generators and portable inverter generators run an internal combustion engine. The fuel used comes from fossil fuels in both cases.

In a conventional generator, each engine rotation produces one block wave of AC power. For the electricity to produce the standard 120-volt, 60-Hz electricity, the engine must run at a constant speed of 3,600 rpm. The speed is constant regardless of the load or the power asked.

An inverter generator is designed to produce more AC electrical energy per engine rotation but not in a form that can be used directly. The raw electricity must first be transformed into DC power.

In an inverter generator, the engine speed varies depending on the electrical demand being asked of it. It has many advantages:

  • Reduces noise

  • Reduces fuel consumption compared to a standard portable generator.

  • It reduces its weight and size, and power that is ultra-clean.

  • It is more efficient than the conventional model.

What Are Transfer Switches?

A transfer switch is an electrical switch that switches a load between two sources. Some transfer switches are manual. In that, an operator effects the transfer by throwing a switch, while others are automatic and trigger when they sense one of the sources has lost or gained power.

It is widely used in the power industry service centers to ensure an uninterrupted power supply to consumers.

In the power industry: an automatic transfer switch ( ATS ) - an automatic device that carries out automatic input of backup power sources or switching on a switch on which the network is divided.

Consumers: switching device switching (power switch) ( eng.  Transfer switch ) - a device for switching one or more load circuits from one source to another.

Separate installations: automatic switching on of electric motors of reserve mechanisms - switching on of reserve equipment when a violation of the technological mode is detected using relays that react to non-electrical quantities.

Is a Diesel Power Plant Considered an Electrical Generator?

A diesel power plant (diesel generator set, diesel generator) is a stationary or mobile power plant equipped with one or more electric generators driven by a diesel internal combustion engine. There are also power plants driven by a gasoline engine  - a gasoline-electric unit or a gasoline power plant and gas piston power plants.

It should be borne in mind that the terms diesel power plant, diesel-electric unit, and diesel generator are not synonymous:

  • diesel generator - a device consisting of a structurally integrated diesel engine and generator;

  • the diesel-electric unit, in turn, includes a diesel generator, as well as auxiliary devices: a frame, control devices, a fuel tank;

  • a diesel power plant is a stationary or mobile unit based on a diesel-electric unit, which additionally includes devices for power distribution, automation devices, and a control panel.

Typically, such power plants combine an alternator and an internal combustion engine, which are mounted on a steel frame, as well as a plant monitoring and control system. An internal combustion engine drives a synchronous or asynchronous electrical generator.

The connection between the engine and the electric generator is made either directly with a flange or through a damper clutch. In the first case, a two-support generator is used, that is, a generator with two support bearings, and in the second, with one support bearing (single-support).


Published: March 19, 2017
Last review: September 11, 2020