Renewable energy is energy that can be generated and used without depleting the source. Examples of clean energy include hydropower, solar power, wind power, and geothermal energy harnessed from the heat within the Earth. Energy derived from the burning of coal, oil, or uranium is not considered renewable because they are finite resources. While coal is naturally occurring, it takes hundreds of millions of years to form and therefore is not considered renewable on a human timescale.

Click here to read more