Which of the following energy is not high grade energy?

Which of the following energy is not high grade energy?

a. Mechanical work
b. Thermal energy
c. Wind energy
d. Electric Energy

Correct Answer : b. Thermal energy

Explanation :

The conversion of high grade energy to shaft work is exempt from the limitation of the second law of thermodynamics, while conversion of low grade energy is subject to them. Thermal energy is subject to conversion into shaft work thus it is not high grade energy, it is low grade energy.