‌In the current research, seven types of renewable energy sources have been investigated. This research has been done using the review research method. Global energy demand has increased due to population growth and technological development. Therefore, renewable energy and its technology are progressing in all over the world. There are seven types of renewable energy sources in the world, that these sources include hydrogen energy, solar energy, geothermal energy, biomass energy, hydropower energy, ocean energy and wind energy. There is no element abundant hydrogen in the world. Therefore, it is the best renewable energy. Renewable energy sources help to reduce greenhouse gases. These energies do not produce polluting and harmful gases for the atmosphere. These energies can be produced in every regionally and locally, but fossil energy sources exist only in some regions.