Which energy source is renewable?

Which energy source is renewable?

• A. Coal
• B. Oil
• C. Geothermal
• D. Nuclear

Answer: (C)

Renewable energy sources are those that can be replenished naturally on human timescales. Geothermal energy taps heat from inside the Earth, which is continuously produced and kept available by natural processes like radioactive decay and the planet’s residual heat. Harnessing this heat doesn’t consume a finite fuel stock; the source is effectively renewed as heat keeps rising from beneath the surface. That makes it sustainable in the long run, especially when the systems are managed so heat can be reinjected or the reservoir is used at a rate balance with its natural replenishment. Coal and oil, by contrast, come from ancient biological matter compressed over millions of years. Once burned, the useful portion is gone and must wait for new fossil fuels to form—a timescale far beyond human lifetimes. Nuclear energy uses uranium, a finite resource, with additional concerns about waste, which is why it’s not considered renewable.

Renewable energy sources are those that can be replenished naturally on human timescales. Geothermal energy taps heat from inside the Earth, which is continuously produced and kept available by natural processes like radioactive decay and the planet’s residual heat. Harnessing this heat doesn’t consume a finite fuel stock; the source is effectively renewed as heat keeps rising from beneath the surface. That makes it sustainable in the long run, especially when the systems are managed so heat can be reinjected or the reservoir is used at a rate balance with its natural replenishment.

Coal and oil, by contrast, come from ancient biological matter compressed over millions of years. Once burned, the useful portion is gone and must wait for new fossil fuels to form—a timescale far beyond human lifetimes. Nuclear energy uses uranium, a finite resource, with additional concerns about waste, which is why it’s not considered renewable.