Non-Conventional Energy Archives

11. In India, cluster bean (Guar) is traditionally used as a vegetable or

In India, cluster bean (Guar) is traditionally used as a vegetable or animal feed, but recently the cultivation of this has assumed significance. Which one of the following statements is correct in this context?

The oil extracted from seeds is used in the manufacture of biodegradable plastics

The gum made from its seeds is used in the extraction of shale gas

The leaf extract of this plant has the properties of anti-histamines

It is a source of high quality biodiesel

This question was previously asked in

UPSC IAS – 2014

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The question asks about the recent significance of cluster bean (Guar) cultivation beyond traditional uses.
A) The oil extracted from seeds is used in the manufacture of biodegradable plastics: While plant oils can sometimes be used in bioplastics, guar oil is not a prominent source for this purpose.
B) The gum made from its seeds is used in the extraction of shale gas: This is the primary reason for the recent surge in demand and cultivation of guar. Guar gum, specifically its derivative hydroxypropyl guar (HPG), is a key component of the fracking fluid used in hydraulic fracturing to extract oil and natural gas from shale formations. It acts as a thickening agent, helping to carry proppants (like sand) into the fractures and then degrading to allow the flow of hydrocarbons. This statement is correct.
C) The leaf extract of this plant has the properties of anti-histamines: While some plants have medicinal properties, guar is not widely known for anti-histamine properties of its leaf extract.
D) It is a source of high quality biodiesel: Guar seeds contain oil, but it is not typically considered a primary source for high-quality biodiesel compared to other oilseed crops.

– The increased significance of cluster bean (Guar) cultivation is primarily due to the demand for guar gum.
– Guar gum is extensively used in the hydraulic fracturing (fracking) industry for shale gas and oil extraction.

India is the world’s largest producer of cluster beans (Guar). The demand for guar gum is closely linked to the unconventional oil and gas industry, particularly in countries like the United States, where fracking is widely used. This has led to fluctuations in guar prices and cultivation area based on global energy markets.

12. With reference to two non-conventional energy sources called ‘coalbed

With reference to two non-conventional energy sources called ‘coalbed methane’ and ‘shale gas’, consider the following statements :

1. Coalbed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks.
2. In India, abundant coalbed methane sources exist, but so far no shale gas sources have been found.

Which of the statements given above is/are correct?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC IAS – 2014

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The question asks about the correct statements regarding coalbed methane (CBM) and shale gas.
1. Coalbed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks: CBM is primarily methane stored within coal seams. Shale gas is natural gas (which is primarily methane) trapped within fine-grained sedimentary rocks like shale. Shale gas is not a mixture of propane and butane only; propane and butane are components of natural gas liquids (NGLs) or liquefied petroleum gas (LPG), which can sometimes be found alongside methane, but the primary component of shale gas is methane. This statement is incorrect.
2. In India, abundant coalbed methane sources exist, but so far no shale gas sources have been found: India has significant CBM reserves and has commercial production of CBM. India also has estimated shale gas reserves in various basins (e.g., Cambay, Krishna-Godavari, Cauvery basins), and exploratory drilling has confirmed the presence of shale gas. While commercial production is not as developed as CBM, sources have indeed been found. This statement is incorrect.

– Both coalbed methane and shale gas are primarily composed of methane (natural gas).
– Shale gas is found in shale formations, not just a mixture of propane and butane.
– India has identified sources of both coalbed methane and shale gas.

Coalbed methane and shale gas are considered unconventional natural gas sources. Extraction techniques like hydraulic fracturing (fracking) are often used for shale gas and sometimes for CBM, though CBM extraction can also involve dewatering. These sources have gained importance globally as potential energy sources, but their extraction methods also raise environmental concerns.

13. With reference to technologies for solar power production, consider th

With reference to technologies for solar power production, consider the following statements :

1. ‘Photovoltaics’ is a technology that generates electricity by direct conversion of light into electricity, while ‘Solar Thermal’ is a technology that utilizes the Sun’s rays to generate heat which is further used in electricity generation process.
2. Photovoltaics generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC).
3. India has manufacturing base for Solar Thermal technology, but not for Photovoltaics.

Which of the statements given above is/are correct?

1 only

2 only

1, 2 and 3

None

This question was previously asked in

UPSC IAS – 2014

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The correct answer is A.

Statement 1 correctly distinguishes between Photovoltaics (PV) and Solar Thermal technologies. PV converts sunlight directly into electricity using the photovoltaic effect, whereas Solar Thermal technology concentrates sunlight to heat a fluid, which is then used to generate steam to drive a turbine connected to a generator, thereby producing electricity indirectly. Statement 2 is incorrect; Photovoltaic cells inherently produce Direct Current (DC), which is then converted to Alternating Current (AC) by an inverter if needed for grid connection or AC appliances. Solar Thermal power plants typically use conventional generators which produce Alternating Current (AC). Statement 3 is incorrect; India has a significant manufacturing base for both Photovoltaic modules/cells and various components used in Solar Thermal power plants.

Photovoltaics are commonly used in rooftop solar panels and large solar farms. Solar Thermal systems are less common for small-scale applications but are used in utility-scale Concentrated Solar Power (CSP) plants.

14. With reference to the usefulness of the by-products of sugar industry,

With reference to the usefulness of the by-products of sugar industry, which of the following statements is/are correct?

1. Bagasse can be used as biomass fuel for the generation of energy.
2. Molasses can be used as one of the feedstocks for the production of synthetic fertilizers.
3. Molasses can be used for the production of ethanol.

Select the correct answer using the codes given below.

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2013

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The correct option is C, as statements 1 and 3 are correct regarding the uses of sugar industry by-products.

– Statement 1 is correct. Bagasse, the fibrous residue left after crushing sugarcane, is widely used as a biomass fuel to generate steam and electricity in sugar mills. Excess bagasse can also be used for paper production or other industrial purposes.
– Statement 2 is incorrect. Molasses is a viscous by-product obtained from refining sugarcane or sugar beets into sugar. It is primarily used in animal feed, for the production of ethanol, rum, yeast, citric acid, and other fermentation products. It is not a common or significant feedstock for the production of synthetic fertilizers, which are typically produced from natural gas (for nitrogen fertilizers like urea), rock phosphate (for phosphorus fertilizers), and potassium salts (for potassium fertilizers).
– Statement 3 is correct. Molasses is a readily fermentable sugar source and is a major feedstock for the production of ethanol, which can be used as a biofuel.

The sugar industry generates significant amounts of by-products which, when utilized efficiently, can contribute to the economic viability and environmental sustainability of the industry. Bagasse and Molasses are the two main by-products.

15. Biogas is considered to be an excellent fuel which burns without smoke

Biogas is considered to be an excellent fuel which burns without smoke. The main constituent of biogas is :

methane

hydrogen

carbon dioxide

hydrogen sulphide

This question was previously asked in

UPSC CAPF – 2023

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The correct answer is A. Biogas is produced by the anaerobic digestion of organic matter. Its main constituent is methane ($\text{CH}_4$).

– Biogas is primarily composed of methane (typically 50-75%) and carbon dioxide ($\text{CO}_2$) (typically 25-50%).
– Methane is the combustible component of biogas, making it valuable as a fuel.

Other gases present in biogas in smaller quantities include hydrogen ($\text{H}_2$), hydrogen sulphide ($\text{H}_2\text{S}$), nitrogen ($\text{N}_2$), and oxygen ($\text{O}_2$). The proportion of these gases varies depending on the feedstock and digestion conditions. While carbon dioxide is also a major component by volume, methane is the main constituent that provides the energy when burned.

16. Which one among the following is not a renewable energy source?

Which one among the following is not a renewable energy source?

Solar

Wind

Nuclear

Hydroelectric

This question was previously asked in

UPSC CAPF – 2021

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Renewable energy sources are those that are naturally replenished on a human timescale. Non-renewable energy sources are finite and are depleted faster than they can be replenished.

Solar energy, wind energy, and hydroelectric energy are all derived from natural processes that are continuously replenished (sunlight, wind currents, water cycles) and are thus considered renewable. Nuclear energy typically relies on the fission of heavy radioactive elements like uranium or plutonium, which are mined from the Earth and exist in finite quantities. While nuclear fuel sources are substantial, they are not naturally replenished at a rate comparable to their consumption, making nuclear energy generally classified as non-renewable, although it is a low-carbon energy source.

Other renewable energy sources include geothermal energy, biomass energy, and tidal energy. Examples of non-renewable energy sources include fossil fuels (coal, oil, natural gas) and nuclear fuels.

17. Which one of the following is the largest composition in biogas ?

Which one of the following is the largest composition in biogas ?

Carbon dioxide

Methane

Hydrogen

Hydrogen sulphide

This question was previously asked in

UPSC NDA-2 – 2020

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The correct answer is (B) Methane.

Biogas is produced from the anaerobic digestion of organic matter. Its primary components are methane (CH4) and carbon dioxide (CO2). Methane is the main combustible component and typically constitutes the largest proportion of biogas, usually ranging from 50% to 75%. Carbon dioxide is the second largest component, making up 25% to 50%.

Minor components of biogas can include hydrogen (H2), hydrogen sulphide (H2S), nitrogen (N2), oxygen (O2), and water vapour. While hydrogen and hydrogen sulphide are present, their concentrations are much lower than methane and carbon dioxide.

18. Which one of the following statements is NOT correct ?

Which one of the following statements is NOT correct ?

Biomass is a renewable source of energy

Gobar gas is produced when cow-dung, crop residues, vegetable waste and sewage are allowed to decompose in the absence of oxygen

Biogas generation reduces soil and water pollution

Heating capacity of biogas is very low

This question was previously asked in

UPSC NDA-2 – 2020

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Statement D is NOT correct. Biogas primarily consists of methane (about 50-75%) and carbon dioxide (25-50%), with trace amounts of other gases. Methane is a flammable gas with a significant calorific value (heat produced per unit volume/mass when burned). While its calorific value is lower than that of natural gas (which is mostly pure methane), it is comparable to or higher than many other common fuels used in rural areas (like wood or dung cakes) and is sufficient for cooking, heating, and generating electricity, indicating a reasonable heating capacity, not a ‘very low’ one.

– Statement A is correct: Biomass (organic matter) is renewable because it can be replenished relatively quickly through natural processes like plant growth.
– Statement B is correct: Biogas is produced through anaerobic digestion, the decomposition of organic matter by microorganisms in the absence of oxygen. This process is used in biogas plants.
– Statement C is correct: Using organic waste to produce biogas reduces the amount of waste that would otherwise pollute soil and water bodies. The digested slurry (digestate) can also be used as a nutrient-rich fertilizer, replacing chemical fertilizers and improving soil health.

Biogas technology provides a sustainable way to manage organic waste, produce renewable energy, and create organic fertilizer, contributing to a circular economy and reducing greenhouse gas emissions, particularly methane emissions from uncontrolled decomposition.

19. The world’s largest biomass cookstove system for cooking in community

The world’s largest biomass cookstove system for cooking in community kitchen has been installed at

Tirupati

Amritsar

Shirdi

Udupi

This question was previously asked in

UPSC NDA-2 – 2016

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The correct answer is Shirdi.

A large biomass cookstove system for community cooking has been installed at the Shri Saibaba Sansthan Trust (Shirdi) in Maharashtra, recognized as one of the world’s largest.

The community kitchen (Langar/Prasadalaya) at the famous Saibaba temple in Shirdi serves thousands of devotees daily. To manage the massive cooking requirements, a large-scale solar steam cooking system supplemented by a biomass gasifier-based system was installed, often cited as one of the largest of its kind globally, particularly for biomass cookstoves in a community kitchen setting. While other places like Tirupati and Amritsar (Golden Temple, known for its massive Langar) also have large community kitchens, the biomass cookstove system at Shirdi is particularly noted for its scale and technology in this context.

20. Which one of the following is not a bio-mass energy source ?

Which one of the following is not a bio-mass energy source ?

Wood

Nuclear reactor

Gobar gas

Coal

This question was previously asked in

UPSC NDA-1 – 2021

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Biomass energy sources are derived from organic matter, such as plants, animals, and their waste.
A) Wood is organic matter from trees and is a common biomass fuel.
C) Gobar gas (Biogas) is produced by the anaerobic decomposition of organic matter (like cow dung), making it a biomass energy source.
D) Coal is formed from ancient organic matter (plants) under heat and pressure over millions of years. While originated from biomass, it is classified as a fossil fuel and is distinct from renewable biomass sources used today.
B) A nuclear reactor generates energy through nuclear fission, typically using elements like uranium. This process involves the splitting of atomic nuclei and is not related to organic matter or biomass. Therefore, a nuclear reactor is not a biomass energy source.

Biomass energy is considered a renewable energy source (if harvested sustainably), whereas nuclear energy is non-renewable (as the fuel source, like uranium, is finite). Fossil fuels (coal, oil, natural gas) are also non-renewable energy sources derived from ancient biomass.

Biomass can be directly burned for heat/electricity (like wood), or converted into other forms of fuel like biogas (methane) or biofuels (ethanol, biodiesel). Nuclear energy harnesses the energy released from the strong nuclear force within atoms.