Thermal energy is technically heat. With thermal heat we can boil liquids and with the steam you can drive a turbine. The average daily radiation power reaching the earth's surface (based on 24 hours) is approximately 165 W/m² worldwide. The use of solar thermal energy was already practised in ancient Egypt, Mesopotamia and in the early South American advanced civilisations through the architecture of their buildings.
It's an ineffective type of energy production, since it only works with steam and not directly with water. Also, a lot of vapor is produced, which isn't able to turn a turbine.
Examples are solar plants or water heating roofs.
What is water?
a: a liquid
b: a solid
c: a gas
Where does nearly all off the energy in the atmosphere come from?
Wikipedia
Ulza, Lukas, Livia