A theory is. A) a tentative explanation for a set of observations that can be tested by further experimentation. B) a statement describing a relationship between phenomena that is always the same under the same conditions. C) a unifying principle that explains a body of facts and relations.
Renewable energy is the energy which is generated from natural sources i.e. sun, wind, rain, tides and can be generated again and again as and when required. They are available in plenty and by far most the cleanest sources of energy available on this planet.
Four Major Limited Energy Sources . There are four non-renewable energy sources that are used most often, states EIA (Non Renewable). The first three are fossil fuels. This means that they were formed from the remains of plants and animals eons ago. Fossils fuels can be in a solid, liquid, or gas form.