Step 1: Water stored high in a dam has gravitational potential energy. Step 2: When released through pipes it falls, and its potential energy changes to kinetic energy. Step 3: The fast-moving water strikes the turbine blades and makes them rotate – kinetic energy becomes mechanical energy. Step 4: The turbine drives a generator, which converts mechanical energy into electrical energy. Step 5: The chemical → heat chain belongs to thermal power plants, not hydroelectric ones. Answer: Potential → Kinetic → Mechanical → Electrical.