Among the following natural resources, which one is both renewable and relatively inexpensive to use as an energy source?

Introduction / Context:

This question examines understanding of renewable versus non renewable resources and their economic characteristics. Modern energy discussions often compare fuels such as coal with renewable sources like sunlight, wind, and water. A renewable resource is one that is naturally replenished on a human time scale. The question asks which listed resource is both renewable and relatively inexpensive to harness as an energy source.

Given Data / Assumptions:

• Resources considered are sunlight, coal, gold, and minerals in general.
• Renewable means that the supply is naturally replenished and will not be exhausted under normal human use.
• Inexpensive refers to the resource itself, not to the entire technology cost, and is considered in a broad, conceptual way.

Concept / Approach:

Sunlight is a classic example of a renewable resource. The Sun continually emits energy, and for human time scales, this supply is essentially limitless. The energy from sunlight falls freely on the Earth, so the resource itself is free. The cost arises from the technology used to capture and convert it, such as solar panels. Coal, gold, and many minerals are extracted from limited deposits in the Earth crust. They take geological time scales to form and are therefore considered non renewable. They are also costly because mining and processing are resource intensive.

Step-by-Step Solution:

Verification / Alternative check:

In environmental science, lists of renewable resources almost always include solar energy, wind energy, and hydropower. Coal is categorised among fossil fuels, which are emphasised as non renewable and major contributors to pollution. Gold is described as a precious metal with limited reserves and high market price, while general minerals are treated as exhaustible natural resources. This classification confirms that only sunlight meets both conditions in the question.

Why Other Options Are Wrong:

• Coal: Non renewable, releases carbon dioxide and pollutants when burnt, and involves significant extraction cost.
• Gold: Very limited, highly valuable, and not used primarily as an energy source.
• Minerals: Many minerals are finite and expensive to extract and are not directly renewable.

Common Pitfalls:

Students sometimes focus only on cost and not on renewability, which might lead them to think of cheap coal. Others think in the opposite way and consider whether a resource seems natural or man made, instead of using the formal definition of renewable. The correct approach is to check both conditions simultaneously: being naturally replenished and cheap as a resource. Sunlight clearly satisfies both criteria.

Final Answer:

Sunlight is the resource that is both renewable and relatively inexpensive.