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Q95 (IAS/2015) Science & Technology › New Materials, Energy & Environment-linked Tech › Hydrogen energy technologies Official Key

With reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements : 1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products. 2. Fuel cells can be used for powering buildings and not for small devices like laptop computers. 3. Fuel cells produce electricity in the form of Alternating Current (AC). Which of the statements given above is/are correct?

Result
Your answer: —  ·  Correct: A
Explanation

Fuel cells are electrochemical devices that convert chemical energy directly into electricity (DC) and heat, with oxygen passing over one electrode and hydrogen over the other, [1]reacting electrochemically to generate electricity, water, and heat.[1] Therefore, **Statement 1 is correct** - when pure hydrogen is used, the by-products are indeed heat and water.

**Statement 2 is incorrect** because fuel cell systems are excellent candidates for small-scale decentralized power generation and can supply combined heat and power to commercial buildings, hospitals, airports and military installations[2], but they are not limited to large applications. Fuel cell systems are modular and can be set up wherever power is needed[2], meaning they can potentially power small devices as well.

**Statement 3 is incorrect** because fuel cells convert chemical energy directly into electricity (DC)[1], not alternating current (AC). They produce direct current, which would need to be converted if AC power is required for specific equipment.

Therefore, only Statement 1 is correct, making option A the right answer.

Sources
  1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.10 FUEL CELLS > p. 296
  2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Fuel cells for power generation > p. 296
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Q. With reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements…
At a glance
Origin: Books + Current Affairs Fairness: Moderate fairness Books / CA: 7.5/10 · 2.5/10
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This is a 'First Principles' Science question disguised as Current Affairs. While Fuel Cells were in the news, the answer relied entirely on 7th-grade physics (Cells = DC) and basic chemistry (H2 + O2 = H2O). Don't ignore NCERT basics while chasing high-tech magazines.

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
Do fuel cells using pure hydrogen and oxygen to generate electricity emit water and heat as by-products?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.10 FUEL CELLS > p. 296
Presence: 5/5
“Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly and very efficiently into electricity (DC) and heat, thus doing away with combustion. The most suitable fuel for such cells is hydrogen or a mixture of compounds containing hydrogen. A fuel cell consists of an electrolyte sandwiched between two electrodes. Oxygen passes over one electrode and hydrogen over the other, and they react electrochemically to generate electricity, water, and heat.”
Why this source?
  • Directly describes fuel cells as electrochemical devices that convert fuel into electricity and heat.
  • Specifies that oxygen and hydrogen react electrochemically over electrodes to generate electricity, water, and heat.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Types Of Hydrogen Based On Extraction Methods > p. 298
Presence: 2/5
“zz,to,z, Types Of Hydrogen Based On Extraction Methods Depending on the nature of its extraction, hydrogen is categorized into three categories, namely, grey, blue and green. • Grey Hydrogen: it is produced via coal or lignite gasification {black orbrown}, or via a process called steam methane reformation (SMR) of natural gas or methane (grey). These tend to be mostly carbon-intensive processes. • Blue Hydrogen: It is produced via natural gas or coal gasification combined with carbon capture. storage (CCS) or carbon capture use (CCU) technologies to reduce carbon emissions. . Green Hydrogen: It is produced using electrolysis of water with electricity generated by renewable energy.”
Why this source?
  • Confirms hydrogen is identified as the most suitable fuel for such cells.
  • Provides context on hydrogen as a fuel source, supporting the premise that hydrogen is used in fuel-cell systems.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 2Z:7 COGENERATION > p. 293
Presence: 2/5
“Co-generation is producing two forms of energy from one fuel. One of the forms of energy must always be heat and the other may be electricity or mechanical. energy. In a conventional power plant, fuel is burnt in a boiler to generate high-pressure steam. This steam is used to drive a lurbine, which in turn drives an alternator through a steam turbine to produce electric power. The exhaust steam is generally condensed to water which goes back to the boiler. As the low-pressure steam has a large quantum of heat which is lost in the process of condensing, the efficiency of conventional power plants is only around 35%.”
Why this source?
  • Explains the general concept of producing electricity and heat from a single fuel (co-generation), supporting the plausibility of simultaneous electricity and heat output.
  • Reinforces that energy-conversion systems can yield both electricity and heat as useful outputs.
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