OAS Mains-2019 Daily Answer Writing-27/04/2020

Paper:   General Studies Paper-II

Section:  Science and Technology

Topic:  Science and Technology, Communication

Question 1

What are Fuel Cell Electric vehicles? Highlight the pros and cons of Fuel Cell Electric Vehicles.

Sample Answer

A fuel-cell electric vehicle is essentially a hybrid electric vehicle wherein the internal combustion engine is replaced with a fuel-cell stack. The onboard sources of power include hydrogen as well as an advanced battery system.

The hydrogen, stored in its pure form in high-pressure tanks, is sent through the fuel-cell wherein it is combined with oxygen, resulting in the production of water (H2O) and electricity by an electrochemical process.

The electricity produced is used directly to drive the vehicle with water being the waste and the only emission through the tail-pipe.

Like conventional batteries under the bonnets of automobiles, hydrogen fuel cells too convert chemical energy into electrical energy.


  • Unlike a battery-electric vehicle, which needs to be charged from external sources, a fuel-cell electric vehicle produces its electricity onboard. This drastically reduces the battery capacity and hence the dead-weight which an FCEV needs to carry.
  • Battery-electric vehicle (BEV) these days have 30-50 kWh battery packs, enabling them to average a driving range of approximately 400 km on a single charge. In comparison, an FCEV can travel a distance of up to 650 km with a battery pack of less than 2 kWh.
  • Also, unlike the charge stored in a battery, which tend to discharge within a short duration of time (hours-days), hydrogen, which is the make source of power in an FCEV, can be stored for longer durations (days-seasons).
  • Also, refuelling of hydrogen tank takes just 2-3 minutes, much like filling the car with petrol/diesel, unlike charging a BEV which could still, with even the latest technologies, warrants at the least 30 minutes if connected to a fast-charger.
  • Fuel cells have strong advantages over conventional combustion-based technologies currently used in many power plants and cars, given that they produce much smaller quantities of greenhouse gases and none of the air pollutants that cause health problems.
  • From a long-term viability perspective, FCEVs are billed as vehicles of the future, given that hydrogen is the most abundant resource in the universe.


  • While FCEVs do not generate gases that contribute to global warming, the process of making hydrogen needs energy — often from fossil fuel sources. That has raised questions over hydrogen’s green credentials.
  • Also, there are questions of safety as hydrogen is more explosive than petrol. Opponents of the technology cite the case of the hydrogen-filled Hindenburg airship in 1937.
  • But the Japanese auto industry argues that the comparison is misplaced because most of the fire was attributed to diesel fuel for the airship’s engines and a flammable lacquer coating on the outside.
  • The other major hurdle is that the vehicles are expensive, and fuel dispensing pumps are scarce. But this should get better as scale and distribution improves.

Given the advantages of the technology over BEVs and combustion-based technologies and its potential in significantly reducing environmental pollution, it is important that countries across the world invest in research to fast track the technological development and aid wider adoption of the same.

Question 2

Discuss the advantages and challenges of 5G mobile service.

Sample Answer

5G is a wireless communication technology. It is the next generation mobile networks technology after 4G LTE networks.

Advantages of 5G

  • Faster Data Speed: Currently 4G networks are capable of achieving the peak download speed of one gigabit per second. With 5G the speed could be increased upto 10Gbps.
  • Ultra-low latency: Latency refers to the time it takes for one device to send a packet of data to another device. In 4G the latency rate is around 50 milliseconds but 5G will reduce that to about 1 millisecond.
  • A more Connected World: 5G will provide the capacity and bandwidth as per the need of the user to accommodate technologies such as Internet of Things. Thus, will help to incorporate Artificial Intelligence in our lives.
  • As per the OECD (Organization for Economic Cooperation and development) Committee on Digital Economic Policy, 5G technologies rollout will help in increasing GDP, creating employment and digitizing the economy.


  • Integration of various standards: There are already multiple groups working to come up with standards around interoperability, backward compatibility with older technologies etc. Thus standardization becomes a major challenge faced by 5G.
  • Common Platform: There is no common architecture for interconnecting various engineering practices. Therefore, a common governing body should develop a common platform for all engineering practices.
  • Building Infrastructure: It is a huge task, with issues around spectrum and installing new antennas.
  • Obstacles: Like buildings, trees and even bad weather can cause interruptions which would require more base stations to be built to ensure better connections.
  • India lacks a strong backhaul to transition to 5G. Backhaul is a network that connects cells sites to central exchange. As of now 80% of cell sites are connected through microwave backhaul, while under 20% sites
    are connected through fibre. The former has bandwidth issues as it uses traditional bands while the latter provides low latency and unlimited capacity (a prerequisite for 5G).
  • The Indian market is yet to adapt to 4G completely and has not fully evolved to experience an AI revolution.

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