Photosynthesis is what converts lightenergy from the sun into chemical energy for plants.
Currently, most biofuel is burned to release its stored chemical energy.
Another branch, related to energetics, is concerned with the transformation of chemical energy into other forms of energy - heat, light, electricity.
The main energy used to power the vehicle or other device is from the chemical energy of the battery.
Transformations of electrical into chemical energy are witnessed in the processes of electrolysis (q.v.; see also Electrochemistry and Electrometallurgy).
