Grade 7 → Energy, Work and Power ↓
Renewable and non-renewable energy sources
Understanding energy is fundamental in physics, where we study how energy does wonders around us. It is used in various forms to do work, and it powers every machine that makes life easy and enjoyable. Let's explore the fascinating world of energy by taking a deeper look at the different sources of energy: renewable and non-renewable.
What is energy?
Energy is the ability to do work. Energy is used when you climb stairs, play a sport, read a book, or sit quietly. Energy helps us move objects, light our homes, and run our appliances. It exists in many forms, such as kinetic (motion), potential (stored), thermal (heat), chemical, and electrical energy.
Work and power
Before discussing the types of energy sources, let's quickly understand two related concepts - work and power.
Work
In physics, work is done when a force moves an object a certain distance. The formula for work is:
Work = Force × DistanceFor example, if you push a book across a table, the work done on the book depends on how hard you push it (force) and how far the book moves (distance).
Power
Power is the rate at which work is done. It means how quickly work is done or how quickly energy is transferred. The formula for power is:
Power = Work / TimeIf two persons are running to carry books, the person who carries them faster (consuming more energy in less time) will use more power.
Renewable energy sources
Renewable energy comes from sources that are never exhausted or can be replenished in a human lifetime. These are important in our move towards sustainable and environmentally friendly energy use. Here are some of the major renewable energy sources:
Solar energy
The sun is a powerful energy source, providing the Earth with as much energy every hour as the entire world uses in a year. Solar energy does not produce air pollutants or carbon dioxide. Solar panels capture sunlight and convert it into electrical energy. Imagine a solar-powered calculator that does not need batteries but works by converting sunlight into electricity.
Solar panels absorb sunlight and generate electrical energy, which can be used to power homes and appliances.
Wind energy
Wind energy is created by using moving air to produce electricity. This type of energy is harnessed by wind turbines which look like giant windmills. The moving air (wind) spins the turbine's blades which power an electric generator:
These turbines are often placed in windy areas or near the sea where the wind speed remains constant.
Hydroelectric power
Hydroelectric power is energy derived from the movement of water. The force of flowing water, especially from a dammed river, can turn a turbine connected to a generator that produces electricity. It's like a giant water wheel!
As water flows through the dam, it turns a turbine, converting kinetic energy (dynamic energy) into electrical energy.
Biomass energy
Biomass energy comes from organic material derived from plants and animals such as wood, agricultural crops or even waste. This energy source can be used directly, such as burning wood for heat, or processed into biofuel.
For example, sugar cane can be converted into ethanol to fuel cars, showing how biomass can serve as a source of energy as well as a means of recycling waste.
Geothermal energy
Geothermal energy is derived from the Earth's internal heat, found in rocks and fluids beneath the Earth's crust. This energy can be harnessed using geothermal power plants.
Imagine you are walking on a warm beach. The heat of the earth beneath your feet can be collected and used to produce energy, just as the heat of the beach can be used to heat a home or generate electricity.
Non-renewable energy sources
Non-renewable energy comes from sources that will be exhausted or irreplaceable in our lifetime or even many lifetimes. These include fossil fuels and some other natural resources.
Fossil fuels: coal, oil, and natural gas
Fossil fuels were formed from the remains of plants and animals more than 300 million years ago. These fuels have been the main source of energy because they are rich in energy. However, they also have a significant impact on the environment due to pollution and greenhouse gas emissions.
1. Coal is a black or brown rock that releases a lot of energy when burned. It is mainly used for producing electricity.
2. Oil is a liquid fossil fuel that can be refined into gasoline or diesel to power vehicles, aircraft, and ships.
3. Natural gas is a gas found along with coal and oil reserves, used mainly as a heating, power, and industrial fuel.
Nuclear energy
Nuclear energy comes from splitting atoms to release energy. This energy is used to boil water, make steam to drive turbines, and generate electricity.
Uranium is the primary fuel used in nuclear power plants. Although nuclear power produces minimal emissions, handling nuclear waste and ensuring the safety of the plant is a major concern.
Comparison of renewable and non-renewable energy sources
Both renewable and non-renewable energy sources play a major role in providing the energy required by humans. Take a comparative look here:
| Features | Renewable energy | Non-renewable energy |
|---|---|---|
| Availability | Replenishment abundantly and naturally | Can be finite and terminated |
| Environmental Impact | Low environmental impact | High level of pollution |
| Cost | High initial setup, low operating costs | Usually cheap to setup, expensive in the long run and harmful to the environment |
| Dependency | Varies according to season and resource availability | Reliable and consistent |
Why move to renewable energy?
The following are the major reasons for turning to renewable energy sources:
- Reduction of greenhouse gas emissions: Reduction of the effects of global warming and climate change.
- Durability: Unlimited supply compared to non-renewable resources that can be exhausted.
- Energy Independence: Reducing dependence on imported fuels, promoting local energy sources.
- Health benefits: Reduced pollution leads to better air quality and health.
Conclusion
Energy is essential for all activities that involve work and power and it becomes incredibly dynamic and versatile depending on its source. Understanding the difference between renewable and non-renewable energy sources helps us understand the importance of responsible energy use and management. As the world moves towards green energy solutions, applying knowledge about these energy sources underlines our ability to innovate and implement changes in favor of a sustainable future for our planet and all its inhabitants.
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