Passage

Directions for the following 5 (five ) items : Read the following two passages and answer the items that follow each passage. Your answers to these items should be based on the passages only. Passage-1 Biomass as fuel for power, heat, and transport has the highest mitigation potential of all renewable sources. It comes from agriculture and forest residues as well as from energy crops. The biggest challenge in using biomass residues is a long-term reliable supply delivered to the power plant at reasonable costs; the key problems are logistical constraints and the costs of fuel collection. Energy crops, if not managed properly, compete with food production and may have undesirable impacts on food prices. Biomass production is also sensitive to the physical impacts of a changing climate. Projections of the future role of biomass are probably overestimated, given the limits to the sustainable biomass supply, unless breakthrough technologies substantially increase productivity. Climate-energy models project that biomass use could increase nearly four-fold to around 150 – 200 exajoules, almost a quarter of world primary energy in 2050. However the maximum sustainable technical potential of biomass resources (both residues and energy crops) without disruption of food and forest resources ranges from 80 – 170 exajoules a year by 2050, and only part of this is realistically and economically feasible. In addition, some climate models rely on biomass-based carbon capture and storage, an unproven technology, to achieve negative emissions and to buy some time during the first half of the century. Some liquid biofuels such as corn-based ethanol, mainly for transport, may aggravate rather than ameliorate carbon emissions on a life-cycle basis. Second generation biofuels, based on ligno-cellulosic feedstocks – such as straw, bagasse, grass and wood – hold the promise of sustainable production that is high-yielding and emit low levels of greenhouse gases, but these are still in the R & D stage.

In the context of using biomass, which of the following is/are the characteristic/characteristics of the sustainable production of biofuel ? 1. Biomass as a fuel for power generation could meet all the primary energy requirements of the world by 2050 2. Biomass as a fuel for power generation does not necessarily disrupt food and forest resources 3. Biomass as a fuel for power generation could help in achieving negative emissions, given certain nascent technologies Select the correct answer using the code given below :

(a) 1 and 2 only
(b) 3 only
(c) 2 and 3 only ✓ UPSC's answer
(d) 1, 2 and 3

Why the answer is (c)

• Statement 1 is incorrect because the passage states that biomass use could increase to 150–200 exajoules, which is 'almost a quarter' of world primary energy in 2050, not 'all' requirements.

• Statement 2 is correct as the passage defines the maximum sustainable technical potential as resources used 'without disruption of food and forest resources'.

• Statement 3 is correct because the passage notes that some climate models rely on biomass-based carbon capture and storage, described as an 'unproven technology' (nascent), to achieve 'negative emissions'.

• Therefore, only statements 2 and 3 are characteristics of sustainable production or valid projections based on the text, making option (c) the correct answer.

Why the other options are wrong

(a) 1 and 2 only: Statement 1 is false because biomass is projected to meet only almost a quarter of world primary energy, not all requirements.
(b) 3 only: Statement 2 is also correct, as sustainable biomass production is explicitly defined by the lack of disruption to food and forest resources.
(d) 1, 2 and 3: Statement 1 is incorrect because biomass cannot meet all primary energy requirements, only a fraction of them.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2016, held on 7 August 2016. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.