Passage:
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.

What is/are the present constraint/constraints in using biomass as fuel for power generation ?
1. Lack of sustainable supply of biomass
2. Biomass production competes with food production
3. Bio-energy may not always be low carbon on a life-cycle basis

Select the correct answer using the code given below :

Question

Passage:
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.

What is/are the present constraint/constraints in using biomass as fuel for power generation ?
1. Lack of sustainable supply of biomass
2. Biomass production competes with food production
3. Bio-energy may not always be low carbon on a life-cycle basis

Select the correct answer using the code given below :

Accepted Answer

Correct Option: (d) 1, 2 and 3 The passage explicitly details several current constraints in utilizing biomass for power generation. First, it notes that "The biggest challenge... is a long-term reliable supply delivered to the power plant at reasonable costs," which highlights a "Lack of sustainable supply of biomass" (Statement 1). Second, it states that "Energy crops, if not managed properly, compete with food production" (Statement 2). Third, it mentions that "Some liquid biofuels... may aggravate rather than ameliorate carbon emissions on a life-cycle basis," confirming that bio-energy is not always low-carbon (Statement 3). Since all three statements represent active, recognized constraints mentioned in the passage, they are all valid. Thus, option (d) is the correct answer.

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