At that time, these plants could make electricity more cheaply than hydro plants. Soon they began to underprice the smaller hydroelectric plants. It wasn't until the oil shocks of the 1970s that people showed a renewed interest in hydropower. As people discovered centuries ago, the flow of water represents a huge supply of kinetic energy that can be put to work. Water wheels are useful for generating mechanical energy to grind grain or saw wood, but they are not practical for generating electricity.
Water wheels are too bulky and slow.
A hydro plant uses the force of falling water to make electricity. To make electricity, a dam opens. At the bottom of the penstock, the fast-moving water spins the blades of a turbine. The turbine is connected to a generator to produce electricity. The electricity is then transported via huge transmission lines to a local utility company.