UPSC Prelims 2009 · General Studies
Question 143: Economy and Social Development
In the context of alternative sources of energy, ethanol as a viable bio-fuel can be obtained from
AnswerThe answer is (c).
Sugarcane is the main viable source of bio-ethanol in India: ethanol is made by fermenting molasses, the by-product of sugar making, or cane juice. Using food grains such as rice and wheat, or potato, would compete with food supply, so they are not seen as viable sources here. Brazil also makes ethanol on a large scale from sugarcane.
Why each option is right or wrong
- (a) Potato can be fermented, but it is not a viable source at scale.
- (b) Rice can yield ethanol but competes with food.
- (c) Right: sugarcane (molasses) is the viable source.
- (d) Wheat can yield ethanol but competes with food.
Worth knowing: Ethanol can be made from all four crops; sugarcane is only the most viable source here, and grains such as rice and maize are now used too.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2009, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.