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Q26 (IAS/2019) Environment & Ecology › Pollution & Conservation › Energy and emissions Official Key

In the context of which one of the following are the terms 'pyrolysis and plasma gasification' mentioned?

Result
Your answer: —  ·  Correct: D
Explanation

The correct answer is option D: Waste-to-energy technologies.

Gasification, pyrolysis and plasma technologies heat waste materials to high temperatures, creating gas, solid and liquid residues.[2] Thermal treatment including pyrolysis, gasification, incineration, and plasma gasification is the most commonly employed technique for the generation of energy in different forms and waste-to-wealth.[3] Pyrolysis is a process that breaks down waste materials through heat without the presence of air, resulting in recyclable products such as char, oil, wax, and flammable gases.[4] These technologies are specifically used for converting waste materials into usable energy forms, making them integral to waste-to-energy conversion processes. They have no connection to rare earth element extraction, natural gas extraction, or hydrogen fuel-based automobiles, making options A, B, and C incorrect.

Sources
  1. [1] https://www.no-burn.org/wp-content/uploads/Gasification-Pyrolysis-and-Plasma-Incineration.pdf
  2. [2] https://www.no-burn.org/wp-content/uploads/Gasification-Pyrolysis-and-Plasma-Incineration.pdf
  3. [3] https://pubs.rsc.org/en/content/articlehtml/2025/ma/d5ma00449g
  4. [4] https://link.springer.com/article/10.1007/s43938-025-00079-8
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PROVENANCE & STUDY PATTERN
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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. In the context of which one of the following are the terms 'pyrolysis and plasma gasification' mentioned? [A] Extraction of rare earth e…
At a glance
Origin: Mostly Current Affairs Fairness: Low / Borderline fairness Books / CA: 0/10 · 10/10
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This is a 'Confidence Check' question. 'Pyrolysis' is a standard static concept found in every basic Environment book (Shankar IAS, PMF) under Solid Waste Management. UPSC added the scarier-sounding 'Plasma Gasification' to intimidate you, but the answer was locked in the static syllabus.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Are the terms "pyrolysis" and "plasma gasification" mentioned in the context of extraction of rare earth elements?
Origin: Web / Current Affairs Fairness: CA heavy Web-answerable

Web source
Presence: 5/5
"Gasification, Pyrolysis & Plasma Incineration What are waste gasification, pyrolysis, and plasma treatment/disposal technologies? Gasification, pyrolysis and plasma technologies heat waste materials to high temperatures, creating gas, solid and liquid residues."
Why this source?
  • Explicitly names the three technologies including pyrolysis and plasma (as 'Gasification, Pyrolysis & Plasma Incineration').
  • Describes these technologies in the context of waste treatment/incineration, not rare earth element extraction.
Web source
Presence: 5/5
"Thermal treatment including pyrolysis, gasification, incineration, and plasma gasification is the most commonly employed technique for the generation of energy in different forms and waste-to-wealth"
Why this source?
  • Lists pyrolysis and plasma gasification together as thermal treatment methods used for waste-to-energy.
  • Context is urban waste and energy generation, not extraction of rare earth elements.
Web source
Presence: 4/5
"2.1 Pyrolysis Pyrolysis is a process that breaks down waste materials through heat without the presence of air, resulting in recyclable products such as char, oil, wax, and flammable gases"
Why this source?
  • Provides a definition and context for pyrolysis as a waste-to-energy/waste-management process.
  • Again the context is waste management/energy, with no mention of rare earth extraction.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Pyrolysis/Ga*ification > p. 293
Strength: 4/5
“Pyrolysis is a process of chemical decomposition of organic matter brought about by heat. In this process, the organic material is heated in the absence of air until the molecules thermally break down to become a gas comprising smaller molecules (known collectively as syngas). Gaeificatiorl can also take place as a result of partial combustion of organic matter in the presence of a restricted quantity of oxygen or air. The gas so produced is known as producer gas. The gases produced by pyrolysis mainly comprise carbon monoxide (z5olo), hydrogen and hydrocarbons (r5Yo), and carbon dioxide and nitrogen (6o70). The next step is to'clean'the syngas or producer gas.”
Why relevant

Defines pyrolysis as thermal decomposition of organic matter in absence of air and describes the syngas/char/liquid products produced by heat-driven breakdown.

How to extend

A student could extend this by checking whether similar thermal decomposition is used to break down mineral-bearing matrices or electronic waste to liberate rare earths.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.8 WASTE TO ENERGY > p. 294
Strength: 4/5
“In today's era, there are increasing quantities of waste due to urbanization, industrialization and changes in life patterns which are harmful to the environment. In the recent past, development of technology has helped to reduce the amount of waste for its safe disposal and to generate electricity from it. Waste-to-energy has the potential to divert waste from landfills and generate clean power without the emission of harmful greenhouse gases. This significantly reduces the volume of waste that needs to be disposed of and can generate power Pyrolysis and gasification are emerging technologies apart from the common incineration and biomethanation.”
Why relevant

States pyrolysis and gasification are emerging technologies used to process waste and generate useful products (waste-to-energy).

How to extend

One could reasonably investigate whether these waste-processing routes are applied to wastes that contain rare earths (e.g., electronic waste, monazite processing residues).

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
Strength: 3/5
“Biomass, on the other hand, releases carbon dioxide that is largely balanced by the carbon dioxide captured in its own growth (depending how much energy was used to grow, harvest, and process the fuel) Chemical processes like gasification, combustion and pyrolysis convert biomass to useful products. Combustion being the most common of them. Each of the technologies mentioned produces a major calorific end product and a mixture of by-products. The processing method is selected on the basis of nature.”
Why relevant

Explains gasification/pyrolysis as chemical processes that convert complex feedstocks (biomass) into useful products, showing these are general-purpose high-temperature conversion methods.

How to extend

Use this pattern to ask if the same high-temperature conversion concepts are adapted to mineral or ore processing for REE recovery.

Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 2: The Solar System > Plasma > p. 24
Strength: 4/5
“• Plasma is one of the four fundamental states of matter, the others being solid, liquid, and gas. It is ionised gas (atoms and molecules are converted into ions typically by removing one or more electrons from the outer shell).• Lightning and electric sparks are everyday examples of phenomena made from plasma.• Neon lights could more accurately be called 'plasma lights' because the light comes from the plasma inside of them.”
Why relevant

Defines plasma as an ionised, high-energy state of matter (ionised gas), implying plasma-based processes can provide high temperatures/energies.

How to extend

With basic knowledge that high temperatures can break down or melt materials, a student could test whether plasma gasification is used to treat mineral sands/residues to separate or free rare earth elements.

Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 9: Distribution of World Natural Resources > thorium > p. 40
Strength: 3/5
“Torium is a by-product of the extraction of rare earths from monazite sands. Torium was used for the breeding of nuclear fuel uranium. It is used as a nuclear fuel in aircraft engines. Torium is a very efective radiation shield. India's Kakrapara-1 reactor is the world's frst reactor which uses thorium. Australia, USA, and India have large deposits of thorium, followed by Canada, Brazil, South Africa and Turkey.”
Why relevant

Notes thorium is a by-product of extracting rare earths from monazite sands, identifying a specific mineral source and associated by-products.

How to extend

Combine this mineral-source fact with thermal/thermal-plasma processing clues to explore whether pyrolysis/plasma gasification are applied to monazite sands or their residues to recover REEs or separate thorium.

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