Which of the following is a non-renewable source of energy?
(1) Biogas
(2) Solar
(3) Wind
(4) Coal
Answer: (4) A non-renewable resource is a natural resource that cannot be reproduced, grown, generated, or used on a scale that can sustain its consumption rate. So, coal is a non-renewable source of energy. Once it is depleted, there is no more available for future needs. Fossil fuels (such as coal, petroleum, and natural gas), nuclear power (uranium) and certain aquifers are examples of non-renewable resources. In contrast, resources such as timber (when harvested sustainably) and wind (used to power energy conversion systems) are considered renewable resources. Natural resources such as coal, petroleum (crude oil) and natural gas take thousands of years to form naturally and cannot be replaced as fast as they are being consumed.
