What is Energy?
Energy is one of the most important entities in our universe. We perform many day to day activities. Think, what causes humans to do all the daily activities? This capacity or ability of a body or system to do work is referred to as energy.
Energy is thus a qualitative property that needs to be transferred to another object in order to make it work or function. Energy can neither be created nor destroyed. It can only be transferred or converted from one form to another. As energy exists in multiple forms, it is hard to find a single elaborate definition of it. Energy can be chemical, thermal, mechanical, electrical, nuclear and light etc.
The SI unit of energy is Joule (J), which is defined as the energy spent in making an object move through a distance of 1 m, against a supplied force of 1 newton. We will now discuss a few sources of energy in this article below.
Types of Natural Sources of Energy
Energy sources are of two types:
Renewable energy sources
Non-renewable sources
Renewable Sources of Energy
The sources of energy present on the earth that can get replenished, or recharged without getting exhausted (running out) are called renewable sources of energy. Renewable energy sources are available on a daily or seasonal basis. Renewable sources are clean and do not cause any pollution to the environment. For example: sun, wind and water etc.
The sun is a very essential source of renewable energy in our life. Our sun is a star i.e. its light is internally produced, it does not reflect the light of any other star or body. It is the basic source of heat and light for the entire living world and the source of energy for all ecosystems. Its thermal heat can be used for passively heating buildings and water. Its natural light (daylight) contributes immensely to the reduction of artificial light needed to light our buildings. It is useful for plants to grow. Sun can provide electrical energy with the help of photovoltaic cells (PV Cells), which are made up of silicon or any other material that transforms sunlight into electricity. Solar panels absorb the sunlight and store it in a solar battery. Solar panels convert solar energy into usable electricity by the photovoltaic effect. Solar energy is also used as solar thermal energy.
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Wind energy is an environment friendly and abundantly available source of energy. Windmills are used to harness the wind potential. Wind rotates the turbine's blades, which feeds an electric generator and produces electricity. The turbine makes use of kinetic energy of wind and converts it into mechanical energy. The generator can convert mechanical energy into electricity. Mechanical energy can also be used directly for specific tasks such as pumping water etc.
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Water or hydel energy is the energy derived from the flowing water. Electricity produced by the flow of water using dams is called hydroelectricity. In this process, a hydel dam captures energy from the moving water of the river. This water is made to fall from a great height. The falling water rotates the turbine, which feeds the generator. The dam operators control the flow of water and the amount of electricity produced.
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Non-Renewable Sources of Energy
Non-renewable energy sources are those which are present in a limited quantity. They are exhaustible, and will run out if not used judiciously. These sources cause pollution to the environment because carbon is the main element present in fossil fuels such as coal and petroleum. Most sources of non-renewable energy are fossil fuels. Fossil fuels were created as the remains of terrestrial and marine flora and fauna that decayed millions of years ago and got buried in layers under huge amounts of pressure and heat. Most fossil fuels are burnt to produce energy and electricity. Coal is also a fossil fuel.
Fossil fuels are a valuable source of energy. They can also be stored, piped, or shipped anywhere in the world.
Coal is a black coloured rock-like fuel. We burn coal to get energy. Coal is widely used as a domestic fuel to make food. When coal is burnt, it releases harmful smoke. Coal is essentially formed as a result of decayed vegetation. There are four stages in the formation of coal- peat, lignite, bituminous and anthracite. Coal mainly contains carbon, hydrogen and oxygen.
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Petroleum is a liquid fossil fuel composed of a variety of hydrocarbons. It is a very useful energy source. However, the petroleum that is drilled out from oil wells is crude oil. It has to be refined through a process called fractional distillation, where different hydrocarbons separate to form different fractions. Petrol, kerosene, paraffin, diesel are some of its fractions. Petrol is used as a fuel in vehicles. Petroleum and its products are used not just for transport but also to manufacture many different products such as plastics, tyres and synthetic materials such as polyester. It is a reliable & portable source of energy. However, the burning of both coal and petroleum is harmful to the environment.
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FAQs on Natural Sources of Energy
1. What are the main types of natural energy sources?
Natural energy sources are broadly classified into two main types based on their availability and replenishment rate:
- Renewable Sources: These are sources that replenish naturally over a short period and are considered inexhaustible. They are environmentally friendly and sustainable. Key examples include solar energy (from the sun), wind energy, and hydroelectric energy (from flowing water).
- Non-Renewable Sources: These are sources that exist in limited quantities and take millions of years to form. Once consumed, they cannot be replaced within a human lifespan. The most common examples are fossil fuels like coal, petroleum, and natural gas.
2. What is the ultimate natural source of energy for Earth?
The Sun is considered the ultimate natural source of energy for almost all activities and life forms on Earth. It provides light and heat, drives weather patterns that create wind, and fuels the water cycle for hydroelectric energy. Even fossil fuels are a form of stored solar energy, as they originated from ancient organic matter that relied on the sun for life through photosynthesis.
3. What are the key advantages of using renewable energy sources over non-renewable ones?
Renewable energy sources have several critical advantages over non-renewable ones. The primary benefit is their minimal environmental impact. Unlike fossil fuels, which release harmful greenhouse gases like carbon dioxide when burned, sources like solar, wind, and hydro energy are clean and do not contribute significantly to air pollution or global warming. Additionally, they are sustainable and will not run out, ensuring long-term energy security for the future.
4. How does a hydroelectric power plant generate electricity from water?
A hydroelectric power plant converts the energy of flowing or falling water into electricity. The process involves several key steps:
- A large dam is constructed to store river water in a reservoir, giving the water potential energy due to its height.
- This water is then released through a large pipe (penstock), where its potential energy is converted into kinetic energy as it flows downwards rapidly.
- The forceful flow of water strikes the blades of a turbine, causing it to spin at high speed.
- The spinning turbine is connected to a generator, which transforms this mechanical motion into electrical energy.
5. Why are fossil fuels considered non-renewable sources of energy?
Fossil fuels, such as coal and petroleum, are classified as non-renewable because they are formed from the decomposed remains of ancient plants and animals over millions of years under immense heat and pressure. The rate at which we consume these fuels is drastically faster than the geological timescale required for their formation. Since their supply is finite and cannot be replenished within a human lifespan, they are considered an exhaustible or non-renewable resource.
6. Why are renewable energy sources also known as non-conventional sources of energy?
Renewable sources are often called non-conventional because, for much of modern history, societies have relied heavily on traditional or 'conventional' sources like coal, wood, and oil for energy. The technologies to efficiently harness energy from sources like the sun (solar panels) and wind (wind turbines) are relatively recent developments. As their widespread use was not traditional, they were termed non-conventional to distinguish them from the long-established fossil fuels.
7. What are the environmental consequences of relying heavily on fossil fuels like coal and petroleum?
Heavy reliance on fossil fuels has significant negative environmental consequences. The combustion of coal and petroleum releases large amounts of carbon dioxide (CO₂), a primary greenhouse gas that traps heat in the atmosphere, leading to global warming and climate change. This process also releases other pollutants like sulfur dioxide and nitrogen oxides, which cause acid rain and air pollution, posing risks to ecosystems and human health.
8. How do solar panels convert sunlight directly into usable electricity?
Solar panels, also known as photovoltaic (PV) cells, convert sunlight into electricity through a scientific principle called the photovoltaic effect. These panels are constructed from semiconductor materials, most commonly silicon. When sunlight (composed of photons) strikes the panel, the energy from the photons dislodges electrons from the atoms in the semiconductor. This flow of electrons creates a direct electric current (DC) which can then be captured, converted to alternating current (AC), and used to power electrical devices.
