These are our primary sources of renewable energy. Of course, there are many other fringe sources of energy that are being researched all the time.
However, in order for a renewable energy to truly make sense, it needs to be both scalable and financially sustainable for investors. For the time being, the five listed above are the main sources of renewable energy.
For additional information on the transformation from fossil fuels to alternative energy sources, get the book “The Great Transition: Shifting from Fossil Fuels to Solar and Wind Energy” by Lester R. Brown.