Energy resources are needed to carry out various industrial, household, and transportation activities. There are two kinds of energy sources: Renewable and Non-renewable resources. Considering the benefits of renewable energy sources, their use has been advocated for the past few years. However, they come with their own set of challenges. Find out more about these energy sources, the advantages and disadvantages of each, and the major differences between the two in this article.
Renewable resources of energy are those energy sources that cannot be depleted and will be available for use continuously. They are usually considered to be a clean form of energy meaning they cause relatively lower greenhouse gases emission and help keep the planet safe. Their sources include solar, wind, hydropower, bioenergy, and geothermal energy.
Solar energy refers to the energy obtained from the sun in the form of light and heat. Solar cells can convert sunlight into electrical or thermal energy. Thermal energy is collected using flat-plate collectors, solar ovens, or ponds. Solar cells (or photovoltaic cells) are used to convert solar radiation into electricity through semiconductors.
Although solar energy in itself is a free and unlimited resource, the initial cost of collecting, harnessing, and storing it is quite high thereby limiting its widespread acceptability. Also, it requires large spaces owing to low solar radiation intensity reaching the earth, probably not masked by shadows to ensure maximum efficiency. Despite the high costs, solar cells are profitable in the long run and reduce electricity bills considerably.
Wind energy refers to the conversion of the kinetic energy produced by the wind in motion into electrical energy using wind turbines. When wind hits the turbine’s blades, they rotate and in turn move the turbine connected to them. Thus the kinetic energy of the wind is converted to rotational energy which is converted to electrical energy through the attached shaft. It is one of the cleanest and most energy-efficient technology. However, they are noisy, require a costly setup, and may pose a danger to flying species.
Hydropower refers to the form of energy generated by running water. It has been practised from time immemorial through dams and turbines. Since the water has high kinetic energy, it generates energy when it falls on the turbine. It is not consumed in the process thus making it truly renewable.
Bioenergy refers to the energy derived from recently living biomass. Since they are made up of hydrocarbons along with other constituents, they can be converted into transportation fuels, bioelectricity, biogas, and heat.
Geothermal energy refers to the energy generated by the thermal energy stored in the earth. This energy can be used to heat buildings and water, and to generate electricity. It is a continuous source of energy since heat is produced continuously inside the earth. The most common example of geothermal energy and its use is the hot springs used for bathing.
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As the name suggests non-renewable energy resources are those which will be deleted at some point in the future. Depletion is a misleading term as non-renewable resources are being produced by nature but at a very slow pace and there is a chance we will use them all before they are replenished. Examples of non-renewable energy include nuclear and fossil fuels such as petroleum products, coal, and natural gas. The origin of fossil fuels dates back to approximately 360-300 million years ago when the only living species on the planet earth were plants, plankton, and algae. They were the autotrophs who utilized sunlight to photosynthesize and create their own food and energy. When they died, they got buried at the bottom of the sea and got crushed under the immense heat and pressure of rocks and other sediments accumulating over them. Over millions of years, these biomass converted into fossil fuels.
The use of fossil fuels is a fully developed technique with accessible means to store and transport them to their point of use. However, their extensive use is dangerous to climate change as coal and petroleum products release pollutants (e.g. carbon dioxide, carbon monoxide, sulfur dioxide, nitrous oxide, soot, etc.) upon burning to elevate the greenhouse effect. The greenhouse effect is responsible for the ozone hole, rising temperature abnormally, melting of the polar ice, and increasing sea level.
The third fossil fuel, natural gas, is less harmful than coal and petroleum products and widely used as compressed natural gas and piped natural gas. However, it is also available in limited quantities.
Nuclear fuels such as uranium and plutonium are used in nuclear reactors to produce heat to run turbines. Uranium is found in small amounts in most rocks but is a powerhouse of energy. However, the use of nuclear fuels is disadvantageous owing to its non-renewable nature, production of radioactive waste, threats of spill accidents, etc.
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The major differences between renewable and non-renewable resources are summarised in the table below.
| S. No. | Characteristic | Renewable | Non-Renewable |
|---|---|---|---|
| 1 | Replenishment | They are replenished over time | They cannot be replenished once depleted |
| 2 | Carbon release | Comparatively low carbon release | High carbon emission resulting in climate change |
| 3 | Procurement cost | Nearly zero | High |
| 4 | Infrastructure and Operational costs | High | Low |
| 5 | Area requirements | They require large operational areas | They require compact operating conditions |
| 6 | Impact on environment and humans | No notable adverse effect has been reported | Highly impactful (negatively) in terms of greenhouse gas emissions and related ailments |
| 7 | Examples | Solar, wind, bioenergy, hydropower, and geothermal energy | Nuclear fuels, and Fossil fuels (coal, petroleum, and natural gas) |
Renewable and non-renewable resources constitute natural resources available in plenty on the earth. While non-renewable energy has been in use for decades as compared to most renewable energies, they are considered to be harmful to the environment and living beings. Additionally, they cannot be replenished. Therefore, there is a thrust on replacing the use of non-renewable resources with renewable resources. The latter offers sustainable solutions to our ever-increasing energy requirements. However, technologies need to be developed further to deal with their high infrastructural costs.
Q1. What is the energy efficiency of solar cells?
Ans. Due to the low intensity of solar radiation reaching the earth, the energy efficiency of most solar cells varies from 15-20%.
Q2. What do you understand about the greenhouse effect?
Ans. The greenhouse effect refers to the process of greenhouse gases, present in the atmosphere, absorbing radiation from the sun, not reflecting it back, and thus creating insulation. It maintains the balance between the hot and cold temperatures on the earth. However, when the emission of greenhouse gases increases rapidly, the earth’s temperature begins to rise, creating climatic imbalance.
Q3. How much of the world’s total energy needs are met with renewable resources?
Ans. At present, the world derives nearly 9% of its total energy needs from renewable resources.
Q4. What is the unit of energy?
Ans. The S.I. (International Standard) unit of energy is Joules.
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