This chapter provides the concept and procedure of conversion of potential energy to kinetic energy and its subsequent conversion into mechanical energy for the onward conversion to electrical energy. This transformation of energy is done through a water conducting system, so this chapter describes how stored water is released from a reservoir and flows through an intake to the sedimentation tank and subsequently passes through a low pressure tunnel to a Surge Shaft for an onward journey to the Turbine via Penstock, and finally, discharges to a river through a tail race channel: a complete journey from water to watt.

Additionally, this chapter introduces the idea of Energy Mix and emphasizes hydro power as the leading and most reliable primary energy mix due to its constant and steady flow through Turbine. This clean energy is a possible solution that can dominate world's energy mix as a cooler solution to a hotter earth.

This chapter discusses various types of hydro power projects varying from large to small, from mini to micro and pico and its merits and demerits, along with its significant worldwide growth, as it has become the leading renewable energy source for generation of electricity in the world.