When you hear the words "energy" or "power", the pictures that come to mind should be of someone trying to perform a task or a machine working with great force and speed; for example, a football player kicking a ball. For the football player to kick the ball efficiently, he would need "energy." If the player can kick the ball with great force, it would seem like he has great power. This general understanding is correct. Energy helps an individual complete their work. Power is the rate of consumption of Energy per unit of time. In this sense, Energy and power are related to each other. However, they are also vastly different. This article focuses on the difference between Energy and power, their sources, types, formulas, and measurements for Energy and power.
Energy vs. Power
Energy helps an individual or an object or substance to perform a task. Power is the rate at which one uses this Energy or the rate at which Energy is transferred. Energy is represented by the unit joules, ergs, calories, etc. It is often denoted by the symbol "E". An important area where Energy and power vary is that Energy can get converted from one form to another. Further, Energy can get stored for future use. The top two sources of Energy are renewable Energy and non-renewable Energy. A person can choose between the two depending on a variety of factors like whether or not they are easy to transport, if they are economical, and which one of the two produces the least amount of pollution. There are different types of Energy, Kinetic Energy, Potential Energy, electromagnetic Energy, sound Energy, Thermal Energy, elastic Energy, gravitational Energy, light Energy, etc. Energy is used when any substance performs an act.
Power is measured in watts per second or joules per second. The letter "P" denotes power. Unlike Energy, power cannot be converted or changed from one form to another, nor can it be stored for the future. Different types of power are electric power, human power, optical power, etc. Mechanical devices, electrical apparatuses, devices that provide heat, etc., use power.
Difference between Energy and Power in Tabular Form
|Parameters of Comparison
|Units of Measurement
|Joules, ergs, calories
|Watts (joules per second)
|The symbol "E"
|The symbol "P" denotes power.
|Energy can transform from one form to another.
|Power can be stored.
|Kinetic energy, potential energy, electromagnetic energy, sound energy, thermal energy, elastic energy, gravitational energy, and light energy.
|Electric power, human power, optical power, etc.
|Energy can be stored.
|Power cannot be stored.
|Energy is used to move a car, to fly an airplane, etc.
|Mechanical devices, electrical devices, and devices that provide heat use power.
What is Energy?
The medium which helps an individual or object to do work is called Energy. Energy has different forms; hence it is difficult to put it into a boxed definition. Energy can get transformed from one type to another, and it can get transferred.
Sources of Energy
There are primarily two sources of Energy, renewable sources and non-renewable sources. There are a few qualities to look out for when choosing the optimal energy source,
- Ease of transportation
- Optimum heat production
- Least polluting source
Renewable Sources of Energy
Renewable sources are those that are readily available in nature. They are sustainable forms; that is, they can get regenerated over time. In addition, these types of energy sources do not bring any negative harm to the environment. They are safe. They are comparatively cheap and are easier to maintain.
The chief sources of renewable Energy are:
- Solar Energy (Sun)
- Wind energy
- Biomass from plants
- Geothermal Energy (created from heat within the earth)
- Hydropower (Energy created from water)
Until the 19th century, renewable sources of Energy were the main energy source. People used biomass from plants for heat, transportation, ploughing, and feeding animals. During the early 1900s, non-renewable resources emerged, which led to lesser use of biomass. At that time, only people in rural areas used biomass. In urban areas, biomass was used for generating heat. However, in the 1980s, renewable Energy became popular again because of its ability to help in electricity generation. Nowadays, countries focus on increasing renewable Energy so that they can reduce their carbon dioxide emissions.
Non-renewable sources of Energy
Non-renewable sources of Energy are usually found deep within the earth's crust. They are not sustainable; that is, they require countless years to get replenished. Most non-renewable sources are created using the remains of animals and ancient sea plants; hence these sources are also referred to as fossil fuels. In addition, these sources of energy cause to the environment. Non-renewable sources of Energy are expensive and difficult to maintain, transport, and store.
The chief sources of non-renewable Energy are:
- Natural gas
- Nuclear Energy
- Hydrocarbon gas liquids
Types of Energy
Depending on the use, Energy is of different forms or types. Chiefly, they belong to two categories, Potential Energy and Kinetic Energy. The different types of Energy are as follows,
- Potential Energy: Potential Energy is the stored Energy of an individual or substance because of its position or state.
- Chemical energy- Energy that is stored in the bonds of molecules and atoms. When you burn wood for heat, chemical energy can get converted into thermal Energy. Examples of chemical Energy are Batteries, petroleum, coal, biomass, natural gas, etc.
- Mechanical Energy- When Energy gets stored in materials by using tension; examples are stretched rubber bands, compressed springs, etc.
- Nuclear Energy- When Energy gets stored inside an atom's nucleus. This type of Energy is responsible for keeping the nucleus together. When a nucleus is split or combined, large quantities of Energy are released.
- Gravitational Energy- when Energy is stored in a material's height. As the height and weight of an object increase, the number of gravitational energy increases. Gravitational Energy can be converted into motion energy; an example of gravitational Energy is hydropower.
- Kinetic Energy- The Energy of an individual, object, or system because of the motion of the body or the movement of the particles within it. Kinetic Energy is relative to other moving objects. It is the Energy found in the movement of waves, atoms, substances, electrons, etc.
- Radiant Energy- This is a form of electromagnetic Energy transmitted in transverse waves; examples are light, gamma rays, x-rays, and radio waves.
- Thermal Energy- Another label of thermal Energy is heat. It is the Energy found in the motion of molecules or atoms within an object or substance. When these molecules or atoms move at faster paces the heat/ thermal energy increases; for example, geothermal Energy.
- Motion energy- Energy found in objects that are in motion. Motion energy gets influenced by the speed of the object. The faster an object or substance moves, the more energy it stores; for example, wind energy.
- Sound Energy- This Energy is found in substances in longitudinal waves. The sound Energy gets transferred through objects in a waveform.
- Electrical Energy- When charged particles (electrons) move through wires or similar substances, it produces electrical Energy, for example, lightning.
An additional feature of Energy
One finest qualities of Energy is that it can get transformed from one source into another. Several devices help to transform energy from one form to another. For example, a battery functions by converting chemical energy to electric Energy. Whenever there is a chemical explosion, it converts chemical energy into different forms, thermal Energy and Kinetic Energy.
Energy cannot be straightforwardly measured. Its measurement requires that some amount of work be completed first and then measured based on the Energy consumed. Several devices can help to measure Energy. For example,
- Calorimeter- Used to measure the quantity of heat released or absorbed during chemical reactions or physical changes.
- Thermometer- Used to measure the temperature of individuals, objects, etc.
- Bolometer- used to measure the magnitude of radiation.
Formulas for Calculating Energy
Potential energy (PE): PE = mgh, where "m" refers to mass, "g" refers to gravitational acceleration, and "h" refers to height.
Kinetic energy (KE): KE = 1/2mv^2, where "m" stands for mass, and "v" stands for velocity.
Electric Energy (W): W = Pt, where "P" denotes power and "t" stands for time.
Units used to represent Energy
What is Power?
People utilize Energy to perform tasks. The rate at which Energy gets consumed to complete a task within a specific time is power. An object possesses higher amounts of power when it can complete a work in less time than a counterpart. For example, three mechanical machines X, Y, and Z, are performing the same work. But X completes it in 10 minutes, Y in 20 minutes, and Z in 40 minutes. In this case, all three completed the task, but X finished the task faster compared to Y and Z. Therefore, X has more power.
The unit of power, "watt" was thus named after James Watt. James Watt was an engineer and inventor. He was making improvements to steam engines and created the measurement "horsepower." His experiments led to commendable improvements in the functioning of the steam engine. The scientific community wanting to honour his contributions, named the unit of power "watt." In 1960, "watt" was officially added as a unit of power to the SI.
Types of Power
Just like Energy, power is of different types.
- Electric power- This is the Energy consumed or transferred into an electrical circuit per unit of time. It is the Measurement of Electrical Energy consumed within a particular period. The unit of electric power is a watt or joule per second, and it is calculated using the formula, P= VI.
- Human power- When a human being creates power it is called human power. Human power gets created from the movement within the muscular and skeletal systems within a body.
- Optical power- This is the Energy generated by light (generated by laser beams) per unit of time.
By definition, power is the energy consumed per unit of time. Theoretically, power can be calculated by measuring the energy consumed for a task per second. When calculating the power of an electrical device, one needs to measure the voltage and current.
In theoretical calculations of power, Power (P) = E/t, or W/t, where "E" stands for energy consumed, "W" stands for work done, and "t" stands for the time taken.
The standard formula for electrical power is Power = V * I, where "V" is voltage and "I" is current.
The formula for electric power in resistors is P = I^2 * R, where "I" stands for current and "R" stands for resistance.
Units used to represent power
- Watts- calculated as joules per second or ergs per second.
- Horsepower is used to represent the power of motor vehicles or other machines.
1 horsepower (hp) = 745.7 watt.
Main Differences between Energy and Power (in Points)
- Energy is what gets used when performing a task. Power is the rate at which the Energy gets consumed for said work.
- Energy gets measured as joules, ergs or calories. The measurement of power is in watts per second.
- Energy is usually denoted by the symbol "E", while the letter "P" stands for power.
- Energy can get transformed from one type to another, but power cannot get converted.
- Energy can get stored and kept for future use, while power cannot get stored.
- The different types of Energy are Kinetic, Potential, Electromagnetic, Sound, Thermal, Elastic, Gravitational, Light, etc. In contrast, some of the different types of power are Electric Power, Human Power, Optical Power, etc.
To sum up, Energy and power are vastly different. Energy allows a person or an object to complete a task, while power is the rate at which they complete the task. They are measured as different units and represented by distinct symbols ("E" and "P"). Energy can be transformed and stored for future use, but power cannot get converted into another form or stored.