In the context of energy sources, what does 'renewable' mean?

The term 'renewable' refers to energy sources that can be naturally replenished within a reasonable time frame, ensuring a sustainable supply. This means that these energy sources, such as solar, wind, hydro, and geothermal, are not exhausted when used, as they are continuously generated by natural processes. For instance, sunlight will always be available as long as the sun exists, and wind is a natural phenomenon that continues as long as atmospheric conditions allow.

In contrast, other definitions provided in the options do not fit the concept of renewable energy. For example, the notion that energy cannot be created anew indicates a finite resource, which aligns more with non-renewable energy sources. Additionally, energy that is used up quickly suggests a high consumption rate without the possibility of replenishment, signaling a non-renewable source as well. Lastly, the idea that energy requires fossil fuels for its production characterizes a dependency on non-renewable sources, which directly opposes the concept of renewability. Thus, defining renewable energy as that which can be replenished naturally over time captures the essence of its sustainability and environmental importance.