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In a coal-fired power plant, about 40% of the chemical energy in the coal becomes useful electrical energy. What happens to the remaining energy?
AIt transforms into less useful forms, like thermal energy
BIt is stored indefinitely inside the plant for later use
CIt disappears completely, violating no physical law
DIt is converted entirely back into more coal
Answer & Solution
Correct answer: A. It transforms into less useful forms, like thermal energy
1. Even though total energy is conserved in the conversion process, only about 40% of the coal's chemical energy becomes useful electrical energy.
2. The remaining energy transforms into other, less useful forms, chiefly thermal energy, which is released to the environment through combustion gases and cooling towers.
3. None of this remaining energy simply disappears, since that would violate conservation of energy, and none of it is stored indefinitely inside the plant.
4. It also does not get converted back into coal, since that would reverse the combustion process rather than dissipate as heat.
_Source: OpenStax College Physics (CC BY 4.0), Ch 7 "Work, Energy, and Energy Resources", section 7.6 Conservation of Energy_
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