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Question

Difficulty: HardRenewable and Non-Renewable Natural Resources

Environmental planners categorize energy resources based on their natural replenishment rates relative to human consumption timescales. Which of the following energy resources, despite originating directly from organic plant matter, is classified as a non-renewable natural resource because its natural formation requires millions of years of geological heat and pressure?

  1. Lignite deposits formed from compressed prehistoric vegetationAnswer
  2. B
    Biogas generated from the anaerobic decomposition of agricultural waste
  3. C
    Charcoal produced through the carbonization of harvested firewood
  4. D
    Ethanol distilled from fermented carbohydrate crops such as sugarcane

Answer

Lignite deposits formed from compressed prehistoric vegetation
Lignite deposits formed from compressed prehistoric vegetation are non-renewable because the geological process of coalification requires millions of years under high pressure and temperature. Human extraction consumes these deposits at a rate infinitely faster than their natural formation, making their supply finite.

Step-by-Step Solution

1
Define the fundamental criterion for classifying a resource as non-renewable
A non-renewable resource is one whose rate of consumption exceeds its rate of natural regeneration, effectively making its global supply finite on human timescales.
Replenishment rate relative to human lifespan determines renewable versus non-renewable status.
2
Evaluate the geological timescale of lignite formation
Lignite formation (coalification) requires millions of years of burial, heat, and compression acting on prehistoric swamp vegetation.
Although organic in origin, its formation period is geological rather than biological.
3
Compare lignite with modern organic energy sources
Biogas, charcoal, and bioethanol regenerate within days to decades, whereas lignite takes millions of years.
Therefore, lignite is non-renewable, while the others are renewable energy sources.

Key Concept

Resource Replenishment Timescales and Fossil Fuel Classification
Estimated Time:1m 30s
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Topics

Renewable and Non-Renewable Natural Resources

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