What is Renewable Energy?
Renewable energy, as the name suggests is an energy that can be renewed or replenished. It is often referred to as 'clean energy' because it is less harmful to the environment as compared to non-renewable energy. Renewable energy is obtained from natural resources and processes that are constantly replenished.
Whenever a question arises about what is renewable energy, we can simply say that it is the energy obtained from the resources which constantly renew themselves, hence it is available in sufficient amounts for our use such that it would not finish no matter how much we use it. Sunlight and wind energy can be taken as an example. These resources keep flourishing even if their availability is dependent on time and weather respectively.
Renewable Energy Definition
It is the type of energy obtained from the resources which do not deplete or replenish themselves within a human's lifetime. It is opposite to the energy obtained from depleting fossil fuels.
Renewable Energy Resources
These are those resources that produce renewable energy. They are mostly present in nature. To the question 'what are renewable energy sources’, we can say that a renewable source is a natural resource that either through natural reproduction or other recurring processes replenishes the depleted or consumed amount of resource within a finite time interval on the human time scale. Solar, wind, biomass, geothermal, and water (hydro) are major renewable resources.
Types of Renewable Energy
Here are some major renewable energy examples.
Solar Energy
Solar energy is the energy obtained from the sun. The radiant light and heat energy are harnessed by solar collectors. The sun's energy can be captured to generate electricity or heat through a system of panels or mirrors.
Solar or photovoltaic cells convert sunlight directly into electricity while solar thermal collectors use heat-absorbing panels and a series of attached circulation tubes to heat water or buildings.
Wind Energy
Wind power or wind energy makes the use of wind to provide mechanical power to electric generators through wind turbines so that they can do operations like milling or pumping. The wind hits two or more propeller-like blades around a rotor. This rotor is connected to the main shaft connected to the generator so that when the rotor moves it moves the shaft in turn, hence electricity is produced as the generator operates. These turbines are installed mostly in high-altitude areas.
Geothermal Energy
Earth has its thermal energy stored in it. The energy that is generated from the thermal energy stored in the earth is called geothermal energy. Hot springs and volcanoes are used to capture the heat energy and this heat is directly used by industries for heating the water and other purposes.
Hydropower
Hydropower or hydroelectricity is the energy generated by the use of water. Dams and reservoirs are constructed on flowing water which uses the kinetic energy of the water to run turbines and in turn, generate electricity. Hydropower is also generated by making use of tides known as tidal energy. Also, energy from the surface of ocean waves is used to produce electricity known as wave energy.
Bioenergy
Bioenergy is derived from biomass which is the organic waste of animals and plants. Biomass contains stored chemical energy. It is burnt to produce bioenergy. It may be converted to biofuel and then used or it can directly be used to produce heat through combustion. The heat generated from combustion is used to run generators to produce electricity.
Importance of Renewable Energy
The importance of renewable energy lies in the need for renewable energy over the conventional form of energy. Some important points are given below.
Renewable energy is a source of clean, inexhaustible energy.
It is pollution-free as it does not produce any greenhouse gas and polluting emissions which are otherwise produced in the case of non-renewable sources.
The costs for renewable energy are also falling at a sustainable rate opposite to the rate trend of fossil fuels.
It reduces energy dependence on fossil fuels.
It can be easily generated because renewable sources are mostly present all around, there is no non-availability issue.
Both economically and environmentally, renewable technologies are becoming competitive to conventional sources of energy.
Uses of Renewable Energy
The major use of all renewable energies is to generate electricity. In 2018, 26.2 percent of global electricity requirements were fulfilled by renewable energy which is expected to rise to 45 percent by 2040.
Solar energy can be directly used for heating and lighting homes, for hot water heating, solar cooling, etc.
Biomass is also used to heat buildings and provide heat in industries. It is also used as a fuel when converted to liquid biofuel.
FAQs on Renewable Energy
1. What is renewable energy?
Renewable energy is energy derived from natural sources that are replenished on a human timescale. It is often referred to as 'clean energy' because it generates far fewer harmful emissions compared to non-renewable sources like fossil fuels. The core principle is that these sources, such as sunlight and wind, are constantly being renewed by natural processes and will not run out.
2. What are five major types of renewable energy with examples?
The five primary types of renewable energy sources, as per the CBSE syllabus, are:
- Solar Energy: Harnessed from the sun's radiation using photovoltaic (PV) panels to generate electricity or solar thermal collectors for heating.
- Wind Energy: Converted from the kinetic energy of wind into mechanical power using wind turbines, which then drive generators.
- Hydropower: Generated from the force of moving water, such as rivers or tides. Large dams are a common example of hydroelectric power generation.
- Geothermal Energy: Derived from the thermal energy stored within the Earth's crust. It is often captured from hot springs or by drilling into underground reservoirs of steam and hot water.
- Bioenergy: Produced from organic matter known as biomass, which includes plant material, agricultural waste, and animal manure. This biomass can be burned for heat or converted into biofuels.
3. How does renewable energy differ from non-renewable energy?
The main difference lies in their source and sustainability. Renewable energy comes from sources that naturally replenish, like the sun, wind, and water, making them virtually inexhaustible. In contrast, non-renewable energy is derived from finite resources like coal, oil, and natural gas (fossil fuels) that take millions of years to form and are depleted much faster than they are created.
4. What are the main advantages of adopting renewable energy sources?
Adopting renewable energy offers several key advantages, both for the environment and for energy security:
- Environmental Protection: They produce minimal to zero greenhouse gas emissions, helping to combat climate change and reduce air pollution.
- Sustainable Supply: As the sources are naturally replenished, they provide a long-term, sustainable energy supply.
- Energy Independence: They reduce a nation's dependence on foreign fossil fuels, leading to greater energy security.
- Falling Costs: The technology for sources like solar and wind power is becoming increasingly affordable and competitive with conventional energy.
5. How is solar energy converted into usable electricity?
Solar energy is converted into electricity through the photovoltaic (PV) effect. Solar panels are made of semiconductor materials, like silicon. When photons from sunlight strike the PV cells, they transfer energy to electrons, knocking them loose. This creates a flow of electrons, which is a direct current (DC). An inverter is then used to convert this DC electricity into alternating current (AC), which is the standard form of electricity used to power homes and appliances.
6. What are the primary disadvantages or challenges associated with renewable energy?
Despite their benefits, renewable energy technologies face several challenges:
- Intermittency: Sources like solar and wind are not available 24/7. Solar power is not generated at night, and wind power depends on weather conditions.
- High Initial Cost: The upfront investment for installing renewable energy systems, such as solar panels or wind turbines, can be high.
- Energy Storage: Due to intermittency, effective and affordable energy storage solutions, like large-scale batteries, are required to ensure a consistent power supply.
- Geographical Limitations: The efficiency of renewable energy generation is often location-dependent. For instance, wind turbines need windy areas, and geothermal energy is only accessible in specific regions.
7. Why is hydropower, despite being renewable, often debated for its environmental impact?
While hydropower is a renewable source that doesn't produce air pollution, the construction and operation of large dams and reservoirs can have significant negative environmental effects. These impacts include displacing local communities and wildlife, disrupting aquatic ecosystems by altering river flow, and contributing to greenhouse gas emissions through the decomposition of submerged vegetation in the reservoir, which releases methane.
8. How can the issue of intermittency in sources like wind and solar power be addressed?
The challenge of intermittency (when the sun isn't shining or the wind isn't blowing) can be managed in several ways. The most critical solution is energy storage, where excess energy is stored in large batteries or through methods like pumped-storage hydropower for later use. Other strategies include creating a diverse energy mix by combining different renewable sources, developing smart grids for efficient electricity distribution, and geographical dispersion of power plants to smooth out local weather variations.
