Energy is defined as “the ability to do work, that is, the ability to exert a force that causes an object to move. Despite this obscure definition, the meaning of the term is very simple: energy is the force that moves objects. There are two types of energy: potential energy and kinetic energy . The best way to describe them is this: potential energy precedes an action, whereas kinetic energy occurs during an action. Imagine holding your physics textbook in the air. Your book has the potential for downfall, simply because of its elevated position. If you drop the manual, the potential energy turns into kinetic energy, which is the energy that resides in the movement itself. Energy comes in many different forms. Here are some of the most familiar: •mechanical energy: the force of movement behind machines •chemical energy: derived from anything that undergoes a chemical reaction to provide us with heat or sustenance, such as wood, coal, oil, food, etc. •muscle energy: derived from the chemical energy of the foods we eat •thermal energy: converted from heat, such as steam in a steam engine or the heat from exploding gases in a combustion engine •light energy: some organisms, mainly plants, get their energy from the Sun in a process called photosynthesis •electrical energy: an electrical charge associated with electricity, magnets and electric currents •nuclear energy: energy released by atoms and converted into heat, then into electrical energy The most important law to keep in mind when studying energy transfer is the law of conservation of energy . Simply put, there is a finite amount of energy in the world and no energy can ever be created or destroyed. This means that if energy is lost somewhere, it cannot completely disappear. It is transferred to something else. However, it should be noted that no energy transfer is 100% efficient. There will always be a loss of energy in the form of heat and sound. Considering the importance of energy, the fundamental question is: "What process on Earth does not use energy?" Energy is present everywhere around us and even in us, at all times. Energy drives all forms of movement. Walking, running, and cycling use chemical energy, from the food we eat, to fuel our muscles and to keep us moving. Trains use either electrical energy or a combination of thermal and chemical energy, created from fossil fuels. A sailboat, driven by the wind, uses mechanical energy. However, if the energy produced by the wind can move a sailboat, the mechanical energy of the wind can also be transformed into electrical energy by means of a wind turbine. Although we have understood the many aspects of energy physics for a long time, humans are still trying to create better, more efficient processes for capturing and using energy. Energy is a central concept in physics, chemistry and biology, as well as geology and the sciences of the Universe. The notion of energy is therefore natura ...

1. Energy is defined as “the ability to do work, that is, the ability
to exert a force that causes an object to move. Despite this
obscure definition, the meaning of the term is very simple:
energy is the force that moves objects. There are two types of
energy: potential energy and kinetic energy . The best way to
describe them is this: potential energy precedes an action,
whereas kinetic energy occurs during an action. Imagine
holding your physics textbook in the air. Your book has the
potential for downfall, simply because of its elevated position.
If you drop the manual, the potential energy turns into kinetic
energy, which is the energy that resides in the movement itself.
Energy comes in many different forms. Here are some of the
most familiar:
•mechanical energy: the force of movement behind machines
•chemical energy: derived from anything that undergoes a
chemical reaction to provide us with heat or sustenance, such as
wood, coal, oil, food, etc.
•muscle energy: derived from the chemical energy of the foods
we eat
•thermal energy: converted from heat, such as steam in a steam
engine or the heat from exploding gases in a combustion engine
•light energy: some organisms, mainly plants, get their energy
from the Sun in a process called photosynthesis
•electrical energy: an electrical charge associated with
electricity, magnets and electric currents
•nuclear energy: energy released by atoms and converted into
heat, then into electrical energy
The most important law to keep in mind when studying energy
transfer is the law of conservation of energy . Simply put, there
is a finite amount of energy in the world and no energy can ever
be created or destroyed. This means that if energy is lost
somewhere, it cannot completely disappear. It is transferred to
something else. However, it should be noted that no energy
transfer is 100% efficient. There will always be a loss of energy

2. in the form of heat and sound.
Considering the importance of energy, the fundamental question
is: "What process on Earth does not use energy?" Energy is
present everywhere around us and even in us, at all times.
Energy drives all forms of movement. Walking, running, and
cycling use chemical energy, from the food we eat, to fuel our
muscles and to keep us moving. Trains use either electrical
energy or a combination of thermal and chemical energy,
created from fossil fuels. A sailboat, driven by the wind, uses
mechanical energy. However, if the energy produced by the
wind can move a sailboat, the mechanical energy of the wind
can also be transformed into electrical energy by means of a
wind turbine.
Although we have understood the many aspects of energy
physics for a long time, humans are still trying to create better,
more efficient processes for capturing and using energy.
Energy is a central concept in physics, chemistry and biology,
as well as geology and the sciences of the Universe. The notion
of energy is therefore naturally underlying many concerns in
daily life. For example, when we talk about the energy value of
a food, the electricity consumption of a household or the fuel of
a vehicle, the efficiency of a solar panel. On a larger scale, it is
the energy resources of oil, gas or coal that participate in the
economic power of a country and determine its international
influence.
Although being the engine of all evolutions or transformations ,
energy remains however difficult to define. No doubt because it
only manifests itself through its variations. For example, the
chemical energy of a fuel-oxidizer mixture (the reactants) does
not "convert" into heat until the exothermic reaction has
occurred, leading to new chemical compounds (the products).
The thermal energy “released” is equal to the variation of the
interaction energies between the atoms of the reactants and
those of the products.
In the case of an exothermic reaction, we will say that the
products are more “stable” than the reactants. Likewise, the

3. energy of elastic origin stored by a compressed spring only
manifests itself when it is released, when it relaxes, inducing
mechanical effects.We will then define energy rather through
the effects it can produce. Thus, energy is a physical entity
capable (that is, if certain conditions are met), to produce heat
or induce movement. The notion of movement being to be
considered in the broad sense; it can be the displacement of a
body but also that of electrons producing a current or even that
of scattering particles moved erratically by thermal agitation.
The general character of energy implies that it is expressed by
the same unit, in this case the joule (J), in the International
System of Units, independently of the field of physics
considered. Note however that, in certain situations , it appears
more convenient to use conversion units. For example, the
kilowatt-hour (kWh) is the unit of use in industrial and
domestic fields, the electronvolt (eV) in that of atomistics, the
calorie (cal) in that of dietetics and sometimes that of of
thermodynamics. On the other hand, in order to adapt it to the
range of orders of magnitude concerned, the usual multiples and
submultiples (μJ, mJ, KJ, etc.) are used. The joule is a unit
derived from the base units of the International System of Units,
the units of mass, length and time.
The energy representing the same quantity, without distinction
of the physical phenomena to which it relates, it can sometimes
seem clearer, especially in the case of a conversion (or a
transformation), to indicate its origin (or its nature). Energy can
thus appear in different forms (or natures): mechanical
(potential and kinetic), electromagnetic (including
electrokinetics), thermal, chemical, atomic, nuclear.
Energy has the remarkable property of being able to be
exchanged between two (or more) interacting systems, while
globally retaining its quantity. This property is translated, in the
most general way, by the first principle of thermodynamics. It
states that the variation of internal energy [4] (∆U) in a system
is equal to the energy received from the outside (that is to say
from all the systems with which it is in interaction), in the form

4. of work (W) or heat (Q).
It is written: ∆U = W + Q
While conserving itself, energy can change in nature, by
“conversion” (or “transformation”). This property is put to good
use in various technical conversion devices with multiple
applications. For example, a heat engine converts energy of
chemical origin (fuel and oxidizer) into energy of a mechanical
nature, an electric motor that of energy of electrical origin
(supplied by a generator - which also realizes, upstream , a
conversion of energy) into energy of a mechanical nature. These
devices are called "energy converters".
At home, when we light a lamp, we use electricity. This
electricity comes from a power station. The electricity
production takes place in power plants . In a power plant, we
use a primary energy source that we will convert into electrical
energy . At home, when we light a lamp, we use electricity.
This electricity comes from a power station. What are the
different types of power plants? How does each of the plants
work? What are the energies used?
The different types of power plants
The electricity production takes place in power plants. In a
power plant, we use a primary energy source that we will
convert into electrical energy.
a. The thermal power station Coal-fired power plant.
In a thermal power plant, water is heated in a boiler to obtain
pressurized steam. This steam will make it possible to turn a
turbine which will drive an alternator. The alternator will
produce the electricity. The primary energy source used in a
thermal power plant can be coal, natural gas or oil: this is called
fossil energy. fossil fuel comes from the decomposition of
organic matter (mostly of plant origin) over millions of years.
b. The nuclear plant
In a nuclear power plant, water is also heated to obtain
pressurized steam. This steam will make it possible to turn a
turbine which will drive an alternator. The alternator will
produce the electricity.The primary energy source used in a

5. nuclear power plant is uranium (uranium is not a fossil fuel).
c. The hydraulic power station
Hydraulic centrA hydraulic power station (dam) uses the force
of water. The water is sent to a turbine. The turbine drives the
alternator which will produce electricity. The primary energy
source used in a hydroelectric power station is water: this is
referred to as renewable energy.
d. The wind power plant
A wind turbine uses the force of air. The air turns the blades of
the wind turbine which drives an alternator, which produces
electricity. The primary energy source used in a wind power
plant is air: this is called renewable energy.
A power plant consists of a turbine and an alternator. Primary
energy (mechanical or thermal) is converted into mechanical
energy by the turbine. Some of this energy is lost due to
friction. The mechanical energy of the turbine is converted into
electrical energy by the alternator. Part of this energy is lost
due to the heating of the alternator. A power station is therefore
an energy converter.
The different sources of energy
To produce electricity, two types of energy sources are used:
renewable energies and non-renewable energies: An energy is
said to be renewable if its use does not lead to a decrease in its
reserve. Water and wind are renewable energies just like the
sun, wood or geothermal energy (heat from the ground).An
energy is said to be non-renewable if its use leads to a decrease
in its reserve. Oil, coal, natural gas and uranium are non-
renewable energies.
Climate Change
Demand for energy and related services to ensure economic and
social development and improve well-being and health is on the
rise. All societies need energy services to meet basic human
needs(lighting, cooking food, comfort, mobility,
communications, etc.) and to promote production processes.
Since around 1850, the global exploitation of fossil fuels (coal,
oil and gas) increased to provide the bulk of energy supplies,

6. leading to a rapid increase in emissions of carbon dioxide
(CO2). Greenhouse gas (GHG) emissions resulting from the
provision of energy services have significantly contributed to a
historic increase in the concentration of GHGs in the
atmosphere. Recent data confirms that fossil fuel consumption
accounts for the majority of emissions global human-made
GHGs3. Emissions continue to increase and, at the end of 2010,
the concentration of CO2 went to over 390 ppm, which is 39%
more than pre-industrial levels (Qazi, Hussain, Rahim,
Hardaker, Alghazzawi, Shaban, and Haruna, 2019).
Recommended
Solution
s
There are many solutions to reduce GHG emissions from the
energy system while meeting the
global demand for energy services. Some of the possible
solutions such as energy conservation and
improving energy efficiency, abandoning fossil fuels, RE,
nuclear energy and the capture and storage of carbon . A
comprehensive assessment of a given range of mitigation
options would require an assessment of each of these options,
their contribution to sustainable development, and all associated
risks and costs.
In conclusion, energy is what is needed to create movement,
deformation, heat, electric current, electromagnetic radiation or
various chemical reactions. Moving cars, wind, water retained

7. by a dam, storm clouds, charged batteries and accumulators, hot
radiators, petroleum, potatoes, uranium nuclei, etc. contain
energy, albeit in different forms. Energy can only be transferred
from one body to another and transformed from one form to
another. The body that provides it sees its energy decrease, the
decrease corresponding exactly to the amount of energy
supplied. And the energy of the body that receives it increases,
precisely by the same amount. The total energy is conserved.An
electric power station (thermal, nuclear, hydraulic, wind)
consists of a turbine and an alternator. The turbine captures
primary energy to convert it into mechanical energy. The
alternator will convert this mechanical energy into electrical
energy. During these conversions, some of the energy is lost
through friction or heating. Energy is said to be renewable if its
use does not lead to a decrease in its reserve (water, wind, sun,
wood, geothermal energy). An energy is said to be non-
renewable if its use leads to a reduction in its reserve (coal, oil,
natural gas, uranium).

8. References
Coulson, C. A., & Bell, R. P. (1945). Kinetic energy, potential
energy and force in molecule
formation. Transactions of the Faraday Society, 41, 141-149.
Gielen, D., Boshell, F., Saygin, D., Bazilian, M. D., Wagner,
N., & Gorini, R. (2019). The role of renewable
energy in the global energy transformation. Energy Strategy
Reviews, 24, 38-50.
Qazi, A., Hussain, F., Rahim, N. A., Hardaker, G., Alghazzawi,
D., Shaban, K., & Haruna, K. (2019).
Towards sustainable energy: a systematic review of renewabl e
energy sources, technologies,
and public opinions. IEEE Access, 7, 63837-63851.
Shankar, R. (2019). Law of Conservation of Energy.
In Fundamentals of Physics I (pp. 70-81). Yale

9. University Press.