# Types of Energy : The Definitive Guide ( 2020 )

This is the ultimate guide to Types of Energy in 2020. In this new guide I’ll show you:

• What is Energy?
• Types of Energy
• Sources of energy
• Examples and applications of different forms of energy in Real life
• Lots more

Let’s get started.

## What is energy?

In physics, energy is defined as the ability to do work.  In technology and economics, energy refers to a natural resource including its associated technology) to be able to extract it, transform it and give it an industrial or economic use.

## Types of Energy

### Mechanical energy

In modern classical physics, the universal law of conservation of energy which is the foundation of the first principle of thermodynamics – indicates that the energy linked to an isolated system remains constant over time.
This means that for many classical physical systems, the sum of mechanical energy, heat energy, electromagnetic energy, and other types of potential energy is a constant number.
For example, kinetic energy is quantified as a function of the movement of matter, potential energy according to properties such as the state of deformation or the position of matter in relation to the forces acting on it, thermal energy according to its heat capacity, and chemical energy according to the chemical composition
In the theory of relativity, the principle of conservation of energy is fulfilled, although the measure of energy must be redefined to incorporate the energy associated with the mass, since in relativistic mechanics if we consider the energy defined in the mechanical way classic then would be an amount that is not kept constant.
Thus, the theory of special relativity establishes an equivalence between mass and energy by which all bodies, by virtue of being made of matter, possess an additional energy equivalent to E= mc² and if the principle of conservation of energy is considered, this energy must be taken into account to obtain a conservation law (in contrast, the mass is not conserved in relativity, but the only possibility for a conservation law is to count together the energy associated with mass and all other forms of energy).
In quantum mechanics, the result of the measurement of magnitude in the general case does not give a deterministic result, so it is only possible to speak of the value of the energy of measurement, not of the energy of the system.
The value of energy, in general, is a random variable, although its distribution can be calculated, although not the particular result of a measurement. In quantum mechanics, the expected value of the energy of a steady-state remains constant.
However, there are non-Hamiltonian states for which the expected energy of the state fluctuates, so it is not constant. The variance of the measured energy can also depend on the time interval, according to the Heisenberg indeterminacy principle.
Energy is a property of physical systems, it is not a real physical state, nor an “intangible substance.” However, there are those who, like Wilhelm Ostwald, have considered energy as the real thing, since, according to the equation of equivalence, the mass that is the measure of the quantity of matter, can be transformed into energy and vice versa.
Therefore, it is not an abstraction, but an unchanging reality, unlike matter. In classical mechanics, it is represented as a scalar magnitude. Energy is a mathematical abstraction of the property of physical systems. For example, a system with zero kinetic energy can be said to be at rest.
In relativistic problems, the energy of a particle cannot be represented by an invariant scalar, but by the time component of an energy-moment quadrisect or ( quad moment ), since different observers do not measure the same energy if they do not move at the same speed with respect to the particle.
If continuous distributions of matter are considered, the description becomes even more complicated and the correct description of the amount of movement and energy requires the use of the energy-impulse tensor.
It is used as an abstraction of physical systems for the ease of working with scalar quantities, compared to vector quantities such as speed or acceleration.
For example, in mechanics, the dynamics of a system can be fully described in terms of the kinetic, potential energies that make up mechanical energy, which in Newtonian mechanics has the property of conserving, that is, being invariant in time.
Mathematically, the conservation of energy for a system is a direct consequence of the evolution equations of that system being independent of the instant of time considered, according to Noether’s theorem.
Energy is also a physical quantity that comes in various forms, it is involved in all processes of change of physical state, it is transformed and transmitted, depending on the reference system and this is preserved.
Therefore, everybody is capable of possessing energy based on its movement, position, temperature, mass, chemical composition, and other properties. In the various disciplines of physics and science, various definitions of energy are given, all coherent and complementary to each other, and all of them always related to the concept of work.
In mechanics are:

• Mechanical energy, which is the combination or sum of the following types:
• Kinetic energy: relative to movement.
• Potential energy: that associated with a position within a conservative force field. For example, there is gravitational potential energy and elastic potential energy or deformation energy, so-called because of elastic deformations. A wave is also capable of transmitting energy by moving through an elastic medium.

In electromagnetism we have:

In thermodynamics are:

• Internal energy, which is the sum of the mechanical energy of the constituent particles of a system.
• Thermal energy, which is the energy released in the form of heat.
• Thermodynamic potential, the energy-related to the state variables.

#### Relativistic physics

In relativity are:

• The energy at rest, which is the energy due to mass according to the well-known Einstein formula , E = mc 2, which establishes the equivalence between mass and energy.
• Decay energy, which is the difference in resting energy between the initial and final particles of a decay.

In general relativity, the gravitational “field” is not properly an ordinary physical field, which leads to difficulties in attributing given energy to an uninsulated system, since a non-stationary gravitational field does not give rise to well-defined potential energy.

#### Quantum physics

In quantum physics, energy is a quantity linked to the Hamiltonian operator. The total energy of a non-isolated system may in fact not be defined: at a given moment the energy measurement can yield different values ​​with definite probabilities.
In contrast, for isolated systems in which the Hamiltonian does not explicitly depend on time, the stationary states do have a well-defined energy. In addition to the energy associated with ordinary matter or matter fields, in quantum physics the following appears:

• Vacuum energy: a type of energy existing in space, even in the absence of matter.

#### Chemistry

In chemistry some specific forms not mentioned above appear:

• Ionization energy, a form of potential energy, is the energy it takes to ionize a molecule or atom.
• Bond energy is the potential energy stored in the chemical bonds of a compound. The chemical reactions release or absorb this kind of energy, depending on the enthalpy and caloric energy.
If these forms of energy are the consequence of biological interactions, the resulting energy is biochemical, since it needs the same physical laws that apply to chemistry, but the processes by which they are obtained are biological, as a general rule resulting from cellular metabolism (see Metabolic path )

We can find examples of chemical energy in the life of living beings, that is, in biological life. Two of the most important processes that need this type of energy are the photosynthesis process in plants and respiration in animals. In photosynthesis, vegetables use chlorophyll to separate water and then convert it to hydrogen and oxygen: hydrogen, combined with carbon from the environment, will produce carbohydrates. The opposite happens in breathing: oxygen is used to burn carbohydrate molecules.

### Units of energy measurement

The unit of energy defined by the International System of Units is July, which is defined as the work done by a force of one newton in a displacement of one meter in the direction of the force. That is, it is equivalent to multiplying a newton by a meter. There are many other energy units, some of them deprecated.

Name Abbreviation Joule equivalence
Calorie lime 4.1855
Frigory fg 4,185.5
Therm th 4 185 500
Kilowatt-hour kWh 3,600,000
Large calorie Lime 4,185.5
Tonne of oil equivalent Tep 41,840,000,000
Tonne of coal equivalent Tec 29,300,000,000
Electron volt eV 1,602176462 × 10 -19
British Thermal Unit BTU 1055,05585
Horsepower per hour 8 CV h 3,777154675 × 10 -7
Erg erg 1 × 10 -7
Foot per pound ( Foot pound ) ft × lb 1,35581795
Pie-poundal 9 ft × pdl 4.214011001 × 10 -11

## Energy as a natural resource

In technology and economics, an energy source is a natural resource, as well as the associated technology to exploit it and make an industrial and economic use of it. The energy in itself is never good for final consumption but an intermediate good to satisfy other needs in the production of goods and services. Being a scarce commodity, energy has historically been a source of conflict for the control of energy resources.
It is common to classify energy sources according to whether or not they include the irreversible use of certain raw materials, such as fuels or radioactive minerals. According to this criterion, we speak of two large groups of technologically exploitable energy sources:

### Renewable energy sources

• Wind energy
• Geothermal energy
• Hydraulic power
• Tidal energy
• Solar energy
• Biomass
• Tidal energy
• Blue energy
• Thermoelectric energy
• Fusion nuclear energy

Non-renewable (or nuclear- fossil ) energy sources :