Which of the following is an example of a renewable energy resource ?

Question

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Correct — option (4), Geothermal energy, is a renewable energy resource. It draws on the heat continuously generated deep within the Earth by the natural radioactive decay of minerals in the core and mantle, a heat source that is effectively inexhaustible on any human timescale and is continuously replenished rather than drawn down like a stock of buried fuel. This heat can be tapped wherever it reaches close enough to the surface — through hot springs, geysers, or engineered wells into hot rock — to generate electricity or provide direct heating, without consuming a finite deposit in the process. That renewability, driven by an ongoing planetary heat-generation process rather than the slow geological accumulation of ancient organic matter, is exactly what separates geothermal energy from the other three options, all of which are fossil fuels.

Why the other options are wrong — (a) Coal is a fossil fuel, formed over millions of years from the compression and chemical alteration of ancient plant matter under heat and pressure. Because it takes geological timescales to form, any coal extracted and burned today is effectively gone for good within a human lifetime — it is a stock resource that is depleted with use, which makes it non-renewable, not renewable.  (b) Petroleum is likewise a fossil fuel, formed from the remains of ancient marine organisms buried and transformed over millions of years under heat and pressure. Like coal, it exists in a fixed, finite geological stock that is consumed and not replenished on any timescale relevant to human energy planning, making it a classic non-renewable resource rather than a renewable one.  (c) Natural gas is also a fossil fuel, formed alongside coal and petroleum through the same slow geological processes acting on buried organic matter over millions of years. Despite being cleaner-burning than coal or oil, it is extracted from a finite underground reserve and is not naturally replenished at any pace that matters for renewability, so it belongs with the other fossil fuels as a non-renewable resource.

Concept: Energy resources are classified as renewable or non-renewable based on the rate at which nature replenishes them relative to the rate humans consume them. Renewable resources — solar, wind, hydro, geothermal, tidal, biomass — are continuously or rapidly regenerated by ongoing natural processes and are not depleted by use in any meaningful human timescale. Non-renewable resources — coal, petroleum, natural gas, and nuclear fuel minerals — exist as finite geological stocks laid down over millions of years, and every unit consumed reduces the remaining stock permanently. Geothermal energy is renewable specifically because its source, the Earth's internal heat from radioactive decay, is continuously generated rather than being a fixed deposit of ancient organic matter.

State PCS 2025 Q34 — Environment & Ecology PYQ with Answer

State PCS 2025 Q34 — Environment & Ecology PYQ with Answer