Both in the real world and in engineering, energy is a very important term to be considered. Different kinds of fields consider energy in different means. Even in spiritual actions, energy is a very important topic. But in this article, we will consider energy more scientifically and technically.
In nature, energy has various forms. And these forms of energy are converted between themselves. Already the laws of thermodynamics that energy is not destroyed or created, it is converted. Here we elaborate on the forms of energy in nature.
Forms of Energy in the Nature
In the scientific technique, when energy is on hand, there is a strict definition of a system. A system is a defined section of space with closed boundaries to be examined. In this examination, all the parameters that come to systems and go from the system are calculated. One of these parameters is energy.
If we think about the total energy of a system, it is the combination of all the forms of energy. This system probably has a mass and if the total energy is divided by the total mass of the system, the unit energy can be calculated.
The total energy of the system includes;
- Mechanical energy
- Kinetic energy
- Potential energy
- Electrical energy
- Magnetic energy
- Chemical energy
- Nuclear energy
The combination of all of these energy types of a system gives the total energy of the system. Calculation of the total energy is not easy stuff. There are different kinds of energies from different kinds of viewpoints. It is very hard to calculate the total nuclear energy of a system for example.
But in general, scientific and engineering studies deal with the net energy changes of the system. So, total energy entering or leaving the system can be calculated easily. In general, one or two forms of energy change in most technical or scientific systems.
Kinetic energy is a form of energy that is calculated with the relative velocity according to a reference point. While calculating the kinetic energy of a system, the velocity of the relative point is assumed to be zero. And the velocity of the system is defined according to that reference point and it is calculated via the formula;
According to this formula, there is a direct proportion between the kinetic energy and the square of the increasing speed. And the direct proportion between the kinetic energy and the mass of the system.
In mechanical applications where speed is an important parameter, kinetic energy calculations are generally made.
Potential energy is related to the height of the system from the earth. So, it is a relative value according to the gravity of the earth. The formula of the potential energy is;
According to this formula, potential energy is also directly proportional to the increasing height and the mass of the system. ‘g’ is the gravitational acceleration constant which has the value of 9.81 m/s^2.
In some engineering systems, the transition between kinetic and potential energy is used. In hydroelectric energy plants, water is taken from the high elevations and drained through channels to power generation turbines. The potential energy of the water is transferred to kinetic energy. This kinetic energy is converted to mechanical rotational energy by the turbine. With electrical generators, this mechanical rotation energy is converted to electrical energy.
As you see above, macroscopic energy conversions are used in lots of engineering systems.
The chemical energy of the systems is a part of total internal energy. The total internal energy of the system is denoted by ‘U’ in physical and thermodynamics calculations. Because in physical and thermodynamical calculations, there is no need for calculations about internal energies.
Chemical energy is associated with the binding energies between atoms and molecules of the system. When chemical reactions occur, this energy can be released as heat or other forms of energy.
The chemical energies of fossil fuels are extensively used in many systems. In internal combustion engines, fuel is burnt to produce mechanical energy. And other kinds of chemicals and molecules are produced such as CO and CO2 and water. The burning of fossil fuels is very harmful to the environment. There is a great transition from fossil energy sources to green energy sources because of this issue.
Atoms of a system constitute nucleus elements such as neutrons and protons. The bonding energy between these sub-atomic particles is called nuclear energy. Nuclear energy is also a part of the total internal energy of systems.
Nuclear energy sources are also heavily used around the world. Compared with fossil energy, nuclear energy systems are much more green and the total produced energy is much higher than other forms of energy types.
Nuclear energy is also used in aircraft ships in the US. The engine of these aircraft carriers is energized by nuclear energy-powered systems.
Electrical energy is also the type of internal energy of a system. Electrical energy is directly related to electricity and the total electric charge of the systems. The voltage difference is a very important parameter to expose this electrical energy to surroundings.
Electrical batteries are the most important applications of electrical energy. There is a total voltage difference in the discharge of electrical energy from the battery to the surroundings.
Mechanical energy is a form of energy that other types of energies are converted into it to obtain a useful form of energy. In most, engineering systems, different types of energy sources are converted into mechanical energy. In general, mechanical energy is produced as the rotation of a physical part. For example in power plants, nuclear, fossil, or other types of raw energy types are converted into mechanical energy by the rotating turbines.
In internal combustion engines, the chemical energy of the fuel is used to rotate the crankshaft. The rotation of the crankshaft is transmitted to the wheels of the car.
We can say that mechanical energy is derived and more useful form of energy for most engineering systems.
Magnetic energy is a type of the total internal energy of the system. Magnetic energy is produced with magnetism between materials and systems. This magnetism can be natural or artificial. There are systems where magnetic energy is converted into different kinds of energy. In induction hobs, magnetic energy that is created with the electrical current through the coils is converted to the heat energy to cook.
Sensible and Latent Forms of Energy
In systems, there is an energy form that is called sensible energy. Sensible energy is related to the motions of atoms and molecules in the system. Think about gas in a container. When you heat the gas, the pressure and the temperature of the gas inside the container increase. Because the kinetic energies of atoms and molecules increase. This is called sensible energy of the systems.
Latent energy is another form of sensible energy which is about the phase changes of the systems. For example, in the phase of water from solid to liquid, there is no temperature change occurs. Just the state of the water molecules changes. In this change, energy dissipated which is called latent energy of the water.
Latent and sensible energies are dissipated as heat energy. Heat transfer occurs between the systems that have different temperatures.
The topic of energy is a much more detailed phenomenon. But to create a general vision of energy, these summarizations can be very useful for the reader.
Macroscopic and Microscopic Forms of Energy
This is also another classification of the forms of energy. Macroscopic forms of energy are the energy types that change according to the external reference. The most important examples of macroscopic energy are the potential and kinetic energies. For example, the kinetic energy of a system changes according to the velocity of the system. But velocity is a relative phenomenon that is calculated according to a reference point. The velocity of a car is measured according to the stationary World. But the world is not stationary and it goes around the Sun. So the total kinetic energy changes according to where you are looking from.
Microscopic forms of energy are also called internal energy of the system. These energy forms are not related to an outside reference frame. The most important example of internal energy is nuclear energy which is not changed according to the outside physical phenomenons.
In different applications, changes in different energy forms are very important.
Forms of energy can be summarized like above. We would like to give a general vision of the forms of energy without elaborating on the much more mathematical and technical details.
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