Previous Year Question
In the context of which one of the following are the terms ‘pyrolysis and plasma gasification’ mentioned?
Extraction of rare Earth elements
Natural gas extraction technologies
Hydrogen fuel-based automobiles
Waste-to-energy technologies
Correct Answer: D
Detailed Solution
Pyrolysis and plasma gasification are technologies for the thermochemical treatment of waste and the recovery of energy from it.
In pyrolysis, organic material is heated at a high temperature in the absence or extremely limited availability of oxygen.
This process may produce products such as syngas, bio-oil and carbon-rich solid char.
The quantity and composition of the products depend upon the feedstock, temperature, heating rate and reaction duration.
Pyrolysis may be used to treat plastics, tyres, biomass and certain types of solid waste.
In gasification, carbonaceous material is converted into a combustible gas in the presence of a limited quantity of oxygen or steam.
Plasma gasification uses an electric plasma to generate extremely high temperatures.
The extreme temperature can convert the organic fraction of waste into syngas consisting mainly of hydrogen and carbon monoxide.
The inorganic fraction of waste may melt and form a glass-like solid slag.
After purification, syngas may be used to produce electricity, heat, hydrogen or chemical products.
These technologies may be used to treat municipal solid waste, industrial waste, biomass and certain hazardous wastes.
Pyrolysis and plasma gasification differ from ordinary incineration because they produce fuel gas or other useful products under controlled oxygen conditions.
They require waste segregation, gas cleaning and the safe management of residual materials.
High capital cost, substantial energy requirements and emission control are major challenges in their use.
These terms are not directly associated with rare-earth extraction, natural-gas extraction or hydrogen-fuel vehicles.