Question

Which fuel has the shortest span of renewability?

Answer 1

It's solar, because solar energy is a renewable resource that is virtually endless as long as the sun shines.

Answer 2

Renewable resources are the resources of energy which can be rapidly replaced with the natural resources, such processes, such as energy derived from the wind or sun. The renewable fuels are a better way of deriving energy than from the non-renewable fuels such as the fossil fuels (LPG, and natural gas). The biofuels can be derived from the vegetable oils etc).

Hence, the answer is 'biofuels'.