“Renewable energy sources” is a topic of much discussion in the present day. We cannot help but ask the following questions:
• What is the source of renewable energy?
• Where does the new energy come from?
• What are energy sources?
Such questions do not have straightforward answers. By investigating the energy sources in use, we can summarize as follows:
1. Fossil energy sources, such as coal, oil, and gas
2. Bioenergy sources, including corn oil and sugar alcohol
3. Renewable energy sources, for example, solar panel, wind turbine, and hydraulic power
4. Others such as tidal-wave energy, geothermic heat, and so on
5. Nuclear energy sources
We review these energy sources and find that fossil energy is the energy that ...