Is solar energy kinetic or potential: Know the physics
We live in nature, which is full of different types of energies. There is no place in our universe that is a total void – there might not be any mass, but energy will still be lurking there in some form or other.
So, there is immense importance of energy in our universe and also in our daily life as well. Energy is something that cannot be created or destroyed and only transferred from one body to other to avail them to do some cool stuff.
If you think of it in another way – when an object gets heated up, when an object starts to be in motion, when an object stretches, when an object becomes bright, all happen because of energy.
Does not our nature look like an MCU movie with lots of superpowers being available due to energies? Here, in this article, we will discuss the properties of solar energy, which provide nature with superpowers like heat, light, electricity, etc., and also cause different indirect activities.
What is solar energy?
Solar energy is a type of reusable energy that is sourced by the Sun and can be harnessed by installing solar panels and other technologies to generate electricity, heat, etc. The sunlight that reaches Earth daily outplays every other energy source by a huge margin only if it can be harnessed and stored efficiently.
According to MIT News, “a total of 173,000 terawatts of solar energy strikes the Earth continuously. That’s more than 10,000 times the world’s total energy use.” But most of the energy gets reflected from the upper atmosphere.
Due to the requirement of immense space, investment, and advanced technology to collect the energy to put it into use, this reusable energy is still far out of reach to be used regularly.
How is solar energy created?
Sun is just one of the many billion stars in the universe and is a very common one. But, this is an amazing object in our solar system and so not common at all. Without this object, there would be no life, no us!
But where does this enormous energy come from? We know the Sun is massive hydrogen storage, but so is Jupiter; why not Jupiter? Well, the short answer is – pressure. The Sun can comprise 1000 Jupiters. So a considerable pressure makes the hydrogen atoms fuse to helium – the process is called ‘nuclear fusion.’
This continuous chain reaction creates this huge energy. To better understand, this energy makes the Sun’s core temperature almost 15 million degrees Celcius and surface roughly 6000 degrees Celcius. This energy is conveyed by photons to the Earth, other planets, and even places lightyears away into space.
What is kinetic energy?
When a train moves so fast – it possesses kinetic energy. When you are rushing to catch a bus – you possess kinetic energy. But a moving train has greater kinetic energy than yours; on the other hand, a person waiting for a bus at a bus stop does not have any kinetic energy.
Kinetic energy makes an object move. This energy depends on the mass of that object and obviously the motion, i.e., the velocity: the more mass and velocity, the more kinetic energy an object would have.
With the help of kinetic energy, we can do lots of things. The essential thing is to move items from one place to another. In the context of solar energy, the photons move from the Sun to Earth with a certain kinetic energy.
What is potential energy?
Potential energy is stored in an object which has the potential to do work due to the stored energy. An engineer and physicist, William Rankine, coined the term potential energy. Usually, any object with mass has potential energy by default.
On the other hand, potential energy is stored in an object if the object is forced to be at a place or a state. For example, if a spring is forced to contract, it stores energy to do work, and when it is released, the spring stretches. If we go up on a cliff, we store energy to fall to the ground.
Is solar energy kinetic or potential?
Solar energy can be said to be kinetic for three reasons:
- Photon energy: Due to nuclear fusion at the core of the Sun, a huge amount of gamma radiation happens; this gamma-ray becomes normally visible rays gradually as it comes onto the surface of the Sun. The photons come with a certain energy to Earth’s surface. In our context, they come and knock out the electrons in the depletion region – the energy of a photon is purely kinetic.
- Thermal radiation: Heat is one of the primary energies that we get from the Sun. As we heat an object, the random motion of the atoms inside that object increases. The increment of an atom’s motion is basically the manifestation of heat; the heat radiated by the Sun causes this to happen. The particles’ movement due to the Sun’s radiation is also an example of kinetic energy.
- Nuclear fusion: In the Sun, due to huge temperature and pressure, hydrogen atoms start to collide and fuse to helium atoms. A huge amount of energy is produced in this chemical, nuclear reaction. In nuclear fusion or nuclear fission, in both cases, mass converts into energy in the form of kinetic energy.
Solar energy can be said to be kinetic for three reasons:
- Inside nuclei: Inside the Sun, a huge amount of pressure exists. Due to this pressure, every atom possesses a certain quantity of potential energy.
- Stored energy: The solar energy later converted into other forms of energy is basically stored either in a battery or capacitor. Unlike wind energy, whose motion is used to move the turbine and generate the electricity, here we cannot use such type of motion. Instead, we store the energy in devices to use later. In that aspect, it is the potential energy of the Sun that we use to roll the wheel.
Why this debate?
As the title of the article suggests, it is not that clear whether solar energy is potential or kinetic, so we discuss it. In my opinion, solar energy is a mix of both; from the generation of the energy to our usage, kinetic energy helps it in some parts, and potential energy helps it in some other parts.
Many articles actually declare that solar energy is kinetic (or potential). Still, as one can see from the previous discussion, there should not be such a white-black picture of it – it depends on the context you are talking about.
How solar panel works (The photon energy)
The solar panel generates electricity with the most abundant energy source available on Earth, i.e., the Sun. As mentioned earlier, it serves energy more than any other form of energy continuously. The main problem is storing that energy, harnessing it, and using it later for other essential purposes. This solar cell uses the second most object on Earth to make it work, i.e., sand. With some controlled process, sand with carbon makes a semiconductor material, silicon.
To make the silicon work, an electric field needs to be created. That is done by a process called doping. The Valancy of an atom defines the number of electrons in the last shell of that atom. Valency describes whether an atom would capture an electron or donate an electron to make a bond with another molecule and be stable to make compound molecules.
Electrons are stable in pairs. While silicon has 4(two pairs) electrons in its outermost shell, it does not capture or donate any electrons. So there is no possibility of building an electric field. That is why we do doping. The valency of a phosphorous atom is 5 (two pairs of electrons and a single electron), so it has an extra electron that can move freely (moving electron creates an electric current.)
On the other hand, the valency of Boron is 3; it has a deficiency of electrons, which is called a hole. These holes can move freely. But effectively, these atoms are neutral in nature. The upper part of a silicon wafer is doped (n-type doping) with phosphorous, and the lower part is doped (p-type doping) with Boron.
The upper part has negative electrons, which can move freely. Very few of them near the boundary go down to the lower layer to combine with the holes. So the area near the boundary has no free electron or hole, called the depletion region.
As the electrons move from the upper layer to the lower layer, in the depletion region, a positively charged area is created, and below the region, a negatively charged area is formed. So, we get an electric field that acts as a driving force for the following process. Now, the sunlight comes into play.
The photons carry some energy with them, go through the upper layer, and get absorbed by that region, knocking out electrons from silicon atoms and making electron-hole pairs. Due to the driving force from the upper layer to the lower layer, the electrons move to the upper part, and the holes move to the lower part.
When we connect a metal circuit to the upper and lower part, the electrons go via the wire, generating electricity. Continuous photon energy, thus, produces continuous electricity. This unit is called a solar cell, these solar cells are installed on one solar panel, and the panels are installed in an array.
Definite answer: Solar Energy – Kinetic vs Potential
So, before the fusion, the atoms seem to have potential energy, which makes them perform fusion reactions in the form of kinetic energy. As a product, gamma-ray is radiated, pure kinetic energy that becomes visible light photon after losing energy.
The photons enter the solar cell to knock out the electrons and make an electric current. Then that is stored in batteries or capacitors in the form of potential energy. See the confusion?? Compared to the electricity generation methods by wind energy and hydropower, it seems that solar energy is potential. But it totally depends on which form we are considering and when.
Does it impact a regular user?
Nah! For a normal person, it does not matter whether solar energy is kinetic or potential as long as it is used to light up our homes. We do not even care about the working mechanism till it is working efficiently and not harming the pocket much.
But, for science and technology purposes, it is essential to consider every detail of any device. We are on the verge of an energy crisis, so it is always important to track which energy resource is more efficient than another. As solar energy is reusable, we do not need to worry about abundance and efficiency.
Other resources of energy (are they kinetic or potential?)
- Wind energy: The motion of wind is used to move the windmill, which drives the turbine to generate electricity. So wind energy is obviously kinetic.
- Nuclear energy: Nuclear energy is stored in the nuclei of the atoms, which holds all the nucleons together. On the other hand, nuclear fusion or fission generates a huge amount of energy in the form of motion. So, this is both kinetic and potential.
- Electrical energy: This is generated due to the motion of electrons, so it is kinetic energy.
- Tidal energy: With the help of the force generated by tides, this energy is created, so this is also kinetic.
- Biomass: Biomass is the result of photosynthesis, converting the Sun’s heat to a stored form. So it is potential energy.
So we discussed what solar energy is and how it is created. We had a general discussion about kinetic and potential energy. Then we saw how photon energy is used to generate electricity and, at last, compared solar energy with other energy resources to differentiate whether solar energy is kinetic or potential. However, we did not conclude anything and kept that decision to the readers. The main reason for using solar energy is to avoid the future energy crisis our civilization might.