UPSC Prelims Practice Questions — GOBARdhan eyes 10-fold increase in CBG output: Puri

Q1. With reference to compressed biogas (CBG) and fossil-derived compressed natural gas (CNG), consider the following statements: Which of the statements given above is/are correct?

  1. CBG is stored and transported as a liquid at very low temperature, which distinguishes it from CNG.
  2. Raw biogas drawn from a digester can be used directly as CBG, since compression is the only step that separates the two.
  3. CBG is treated as renewable because its carbon was recently absorbed from the atmosphere by plants, unlike the carbon in fossil CNG.
  • A. 1 only
  • B. 1, 2 and 3
  • C. 2 and 3 only
  • D. 3 only

Q2. With reference to anaerobic digestion as used in compressed biogas plants, consider the following statements: Which of the statements given above is/are correct?

  1. The same digestion process can handle feedstocks as varied as cattle dung, sugarcane press mud and sewage treatment plant waste.
  2. Methane in the digester is generated mainly by slow combustion of the organic matter at high temperature.
  3. The slurry left after the gas is extracted retains plant nutrients and can be marketed as a fertiliser product.
  • A. 2 and 3 only
  • B. 1 only
  • C. 1 and 3 only
  • D. 1, 2 and 3

Q3. Consider the following statements: Which of the following is correct in respect of the above statements?

  1. Compressed biogas can be blended into the gas supplied through the CNG (Transport) and PNG (Domestic) segments of city gas distribution networks.
  2. After purification, compressed biogas contains over 95% methane and has a calorific value and other properties similar to CNG.
  • A. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
  • B. Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
  • C. Statement-I is correct, but Statement-II is incorrect
  • D. Statement-I is incorrect, but Statement-II is correct

Q4. With reference to the Compressed Biogas Blending Obligation (CBO) in India, consider the following statements: Which of the statements given above is/are correct?

  1. It applies to the CNG (Transport) and PNG (Domestic) segments of city gas distribution.
  2. It was kept voluntary for an initial period before becoming mandatory.
  3. It is set as a fixed absolute volume of biogas per distribution entity that stays the same every year.
  4. One of its stated objectives is to substitute part of India's imported LNG.
  • A. 1, 2 and 4 only
  • B. 1, 2, 3 and 4
  • C. 2 and 4 only
  • D. 1 and 3 only

Q5. A gram panchayat runs a biogas digester fed with cattle dung and kitchen waste. Gas output falls sharply after a crack lets air flow continuously into the tank. Which of the following best explains the fall?

  • A. Oxygen converts the methane already formed into hydrogen sulphide
  • B. Methane-forming microbes function only in conditions free of oxygen
  • C. Air entry removes the carbon dioxide the microbes need to make manure
  • D. Oxygen speeds up methane-forming microbes, exhausting the feedstock early

Q6. Suppose cattle dung and food waste now left to rot in open dumps are instead fed into sealed digesters, and the compressed biogas produced replaces fossil fuel in vehicles. Which of the following consequences is/are likely?

  1. Methane that would have escaped from the dumps is instead burnt, releasing carbon dioxide, a less potent greenhouse gas.
  2. Net carbon dioxide emissions fall because combustion of fossil fuel is displaced.
  3. Carbon dioxide released at the vehicle's tailpipe falls to zero.
  • A. 2 and 3 only
  • B. 1, 2 and 3
  • C. 1 only
  • D. 1 and 2 only