People, places, and even parties are often described as having good or bad energy, but what is energy? Understanding energy means looking beyond the subjective — something humankind has done since Greek times.People, places, and even parties are often described as having good or bad energy, but what is energy? Understanding energy means looking beyond the subjective — something humankind has done since Greek times.
To scientists, energy is the ability to do work, and it exists in many different forms. Understanding energy — the science and its implications — helps clarify our relationship with our world and universe.
Why Is Energy Important?
The Sun provides the energy that allows almost everything on our planet to survive. Energy continually flows around us, changing our environment as it transforms (for example, moving objects or heating them).
The great Aristotle (384–322 BC) cottoned onto the importance of energy, coining the word “energeia” (ἐνέργειά), which means “to contain work.” His interpretation of energeia was philosophical and not based on science — he reasoned that good behavior was an activity and required energy to bring you happiness.
Scientists now understand that work moves energy from one system to another. Solar energy emitted from the sun is converted into many forms of energy on Earth by plants, humans, and animals. Without the energy from the sun, there’d be no life on Earth.
Why Is Energy So Important In Our Lives?
Energy is vital to life on Earth. The sun radiates more solar energy in one day than our entire world uses in a day, generating nuclear energy from a process called nuclear fusion. The sun’s radiant energy takes eight minutes to reach the Earth, traveling at the speed of light.
Much of the sun’s energy is absorbed by oceans and landmasses, helping to power the water cycle and create wind power. Green plants absorb the sun’s light energy and convert it into water and carbon dioxide as well as oxygen in a chemical process called photosynthesis.
Animals and humans eat these plants, supporting the life cycle in the oceans and on land. The sun’s energy also keeps us warm with its heat energy and provides light during the day. More recently, it has also been harnessed as a renewable energy source.
Solar panels convert the sun’s energy into electricity. Temperature differences create the wind; when the sun warms the air, it rises (high pressure), and colder air (low pressure) rushes into its place, creating wind. Wind turbines turn with this wind, producing electricity to power our homes, cars, and businesses.
We have learned how to change the sun’s energy from one form to another, making our lives easier and more comfortable.
Why Do We Need Energy?
Our bodies need energy to function just as the Earth needs the sun’s energy to support life. We eat plants — considered a compound or element — grown with the sun’s energy. A chemical process in our stomachs breaks down the plant’s chemical bonds, atoms, and molecules, releasing the food’s potential energy into chemical energy.
We use this chemical energy to move around (called mechanical energy), enabling us to do work and activities, creating a cycle of energy. A farmer grows crops thanks to the sun’s energy, the farmer working and moving thanks to the energy transfer from eating last year’s crops, grown with the sun’s energy. We also need energy to maintain our body temperatures, produce new cells, and send messages along our nerve cells.
As well as life’s basics, we harness energy in many ways. Early humans made fires to create thermal energy to survive cold winters, transforming the energy in wood into heat. The food they ate gave them the energy to collect the wood. In today’s modern setting, we burn fossil fuels to create electricity at power stations and burn gas to power transportation.
Where Does Our Energy Come From?
The energy of the Earth comes from our sun. The sun’s energy comes from within itself — high internal pressure and temperatures cause nuclear fission of its hydrogen and helium atoms. During this process, nuclei separate from their electrons. Radiant energy is released as hydrogen nuclei fuse to form one helium atom.The energy of the Earth comes from our sun. The sun’s energy comes from within itself — high internal pressure and temperatures cause nuclear fission of its hydrogen and helium atoms. During this process, nuclei separate from their electrons. Radiant energy is released as hydrogen nuclei fuse to form one helium atom.
It can take around 150,000 years for this energy in the sun’s core to make it to the sun’s surface, then eight minutes to travel to the Earth at 186,000 miles per second (the speed of light). Only one part per every two billion parts of energy the sun radiates strikes the Earth.
Much of what we associate with energy in the modern sense comes from fossil fuels like coal, gas, and oil. Coal, some of which is 300 million years old, was formed by decaying plants that had grown thanks to the sun’s rays. Coal use kick-started the Industrial Revolution, powering steam-driven trains, heating homes, and later driving generators in power stations.
With the advent of widespread electricity use, coal was eventually joined by natural gas power stations and nuclear power plants, all nonrenewable energies. Technology brought energy efficiency and the era of renewables like biomass, solar energy, geothermal, and wind power. All of these are, ultimately, energy conversions from the Sun.
Where Can Energy Be Found?
Energy is invisible yet is found throughout the universe. We’ve seen how plants, humans, and even coal can convert energy into different types of energy. At a molecular level, energy exists in the chemical bonds that keep atoms together, such as electrons and protons. Chemical reactions can release this energy into other forms.
Looking at the bigger picture, the sun emits some of the most recognizable types of energy in light and heat, which can also be called electromagnetic radiation. This electromagnetic radiation is present throughout the universe, and includes gamma rays, X-rays, visible light, infrared rays, and radio waves. It is also known as electromagnetic energy.
Where Does Most of Our Electrical Energy Come From?
In 2018, our electrical energy sources were led by coal, which provided 38% of the world’s electricity. Here’s a global breakdown of the amount of the energy supplied as electricity by various sources:
- Coal 38%
- Natural gas 23%
- Hydropower 16.2%
- Nuclear 10.1%
- Wind power 4.8%
- Oil 2.9%
- Biomass and waste 2.4%
- Solar 2.1%
- Geothermal energy, tidal, others 0.5%
Combustible fuels accounted for 66.3% of the total world gross electricity production in 2018. Electricity generation from renewable sources increased year to year, with wind power (+12.4%) and solar (+24.3%) showing substantial gains, and further gains predicted.
What Are the Types of Energy Sources?
Nonrenewable energy sources include fossil fuels like coal, oil, and natural gas. Nuclear power is also considered a nonrenewable energy source, despite nuclear energy being a renewable energy source. Nuclear is nonrenewable because the material required by nuclear power plants — uranium U-235 — is not a renewable resource.
Renewable energy sources are:
These are renewables because their energy sources renew and replenish. They are always available to us — the sun will always shine, and the wind will always blow, albeit with daily and seasonal variations. Fossil fuels will eventually run out on Earth, whereas renewables won’t.
One of the most significant uses of both renewable and nonrenewable energy sources is to create electricity in power stations. Electricity is a secondary energy source, whereas fossil fuels are primary energy sources.
What Types of Energy Are There?
There are many types of energy, and scientists have defined the two principal types of energy as:
Potential energy: Energy that is stored somewhere
These energies can be subdivided. There are two main types of potential energy, or stored energy: gravitational potential energy and elastic potential energy.
Gravitational potential energy varies depending on the position of an object in relation to the ground. The Earth’s gravitational pull alters the amount of potential energy an object has.
Consider a golf ball lying on the ground; it can’t move much by itself and has very little potential energy. Put that golf ball at the top of a tree. It now has a lot more gravitational potential energy, which is the potential to fall and possibly hit something en route, thanks to the gravitational pull of Earth’s magnetic fields.
Drop a golf ball from a plane at 10,000 feet, and it has even more gravitational potential energy. That stationary golf ball now has enough energy to cause some serious damage, all thanks to its position relative to Earth.
Elastic potential energy happens when you stretch or compress something and give it more energy. If you stretch a rubber band, you have increased its elastic potential energy; what was a limp rubber band can now be pinged at an object. An archer pulling the string on a bow creates the same elastic potential energy, unleashing it when releasing the string and firing an arrow.
There are several types of kinetic energy:
- Nuclear energy; The energy released during nuclear fusion
- Mechanical energy; The sum of potential and kinetic energy, such as pedaling a moving bike
- Chemical energy: Energy stored in compounds and elements, like food or coal
- Electrical energy; Potential or kinetic energy resulting from an electric charge flow; often made at power stations
- Radiant energy: Electromagnetic waves that travel through space, such as from the sun or from a light bulb
- Thermal energy: Heat or thermal energy produced by rises in temperature, such as a kettle boiling
What Type of Energy Is Food?
Food is chemical energy, or energy stored in compounds and elements. Once we eat food, a chemical process breaks down the chemical energy stored within them. Our bodies use this energy to move, talk, and keep warm (kinetic, thermal, and sound energy).
What Are Natural Sources of Energy?
Natural sources of energy, also known as renewables, are replenishable and considered inexhaustible. Earth’s natural sources of energy are solar, wind, water (tidal, hydropower), biomass, and geothermal energy. We harness these in various ways: solar in sunny areas, wind with turbines on tops of hills or at sea, water with running rivers, streams and dams, and geothermal above areas of geothermal activity, to name a few.
Where Is Energy Stored?
According to the Law of Conservation of Energy, energy is not stored anywhere and it cannot be created or destroyed, only transferred or converted from one form of energy into another.According to the Law of Conservation of Energy, energy is not stored anywhere and it cannot be created or destroyed, only transferred or converted from one form of energy into another.
The theory states that a system, such as the universe, always has the same energy. This total energy never changes. When we think about batteries’ energy, it seems we are storing energy away to be used later. This is not true; we are moving energy into a battery that will later convert into another energy.
The First Law of Thermodynamics states that the amount of energy in a system remains constant. It also states that a change in a system’s internal energy is equal to the work done by or to the system and the heat that flows in or out of it.
Real-life examples include humans converting chemical energy in food into kinetic energy by going for a walk and plants converting the sun’s electromagnetic radiation (light energy) into chemical energy.
Where Is Energy Stored in a Molecule?
The bonds keep the molecules together until sufficient force is applied to the molecule to break its covalent bonds. When this happens, the atoms are momentarily free and establish new bonds, forming new molecules. During this process, energy stored in the bonds is released as chemical energy.
These new bonds may have different energy amounts to the original, either lower or higher. When hydrogen and oxygen molecules react together to form water, the energy in the covalent bonds of the hydrogen and oxygen is higher than the hydrogen-oxygen bonds of water.
In this case, there is an “excess” of energy that needs to go somewhere — remember, all energy transforms into another form of energy. In the hydrogen/oxygen example, the excess becomes kinetic energy. It makes the water molecules move faster and further, causing them to heat. So the chemical energy becomes heat energy.
What Is Stored Energy Called?
Stored energy is another name for potential energy, the energy of position within a system.
Can Energy Be Created?
As we’ve seen, energy exists in many forms, such as heat, electrical energy, and light. The Law of Conservation of Energy states that energy can be changed from one form to another. Still, it cannot be created or destroyed.
When we burn coal to power a generator to make electricity it feels like electricity has been created. But in reality, electricity is the form taken for the transformation of energy in the coal.
What Are the Forms of Energy?
We’ve discussed the various forms of energy; potential, kinetic, nuclear, mechanical, chemical, electrical, radiant, and thermal energy.
It’s useful to know how we measure a unit of energy, too. Potential and kinetic energy are measured in Joules (J). We measure electrical energy in kilowatt-hours (kWh).
The British thermal unit, Btu, is a unit of heat, with one Btu as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. The energy content of fuels is often referred to in Btu.
Is Light a Form of Energy?
Light is a form of energy; light energy is a form of electromagnetic radiation that travels in waves. It is a type of kinetic energy and is the only form of energy visible to the human eye.
Why Should We Conserve Energy Resources?
Demand for power and energy is increasing in a world of finite resources. Fossil fuels like oil, coal, and natural gas will eventually extinguish. We require more and more raw materials to build the turbines and solar panels that provide us access to renewable energy sources such as wind and solar.
If we understand that all energy is transferred, making those transfers as clean and as efficient as possible makes sense — we will never be able to access more energy, so we must manipulate what we have to its best use.
What Is Energy? It’s All Around Us
Aristotle understood energy to be philosophical energy. Many modern phrases urge us not to waste energy on lost causes and, conversely, to save the good energy for those who deserve it. We know that throwing away good food is a waste of resources, tossing away energy unnecessarily. Energy helps us lead more comfortable and fulfilled lives, so it’s important to check that your energy broker is offering you the best deal.
Energy is a scientifically measurable force that is present throughout the universe. There will never be any more or less of it within our universe, and it spends its time transforming from one energy type to another. Humans’ ability to capture, measure and transform energy has helped us to create the world we know today.
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