In 1906, a riverboat captain named William Patrick Lay founded Alabama Power to harness the renewable energy of some 77,000 miles of rivers and streams by storing the water that flows through them.

More than 100 years later, hydroelectric generation remains the leading source of renewable energy in the United States and accounts for about 6 percent of Alabama Power’s annual energy generation. But how, exactly, do the company’s 14 hydroelectric facilities – more commonly called dams – convert more than 157,000 acres of standing water into enough energy to power more than 700,000 homes?

The answer is found in Sir Isaac Newton’s law of gravity: Water stored behind these dams creates energy through the movement of falling water that is harnessed by large generators.To create this energy, stored water – called headwater – is moved down through the dam using a large pipe called the penstock. This flowing water turns a propeller-like turbine attached to a generator shaft, which in turn converts the energy of the water into electricity by spinning large electromagnets in the generating unit.

Once the falling water passes through the turbine, it is returned to the river through a draft tube.

This electricity produced by Alabama Power dams is a small portion of the company’s overall generation, but serves an important role in maintaining transmission and distribution system reliability. Because hydro plants are able to generate electricity almost as soon as water begins moving through their turbines, dams are able to provide crucial and almost instant support during peak customer use, such as hot summer afternoons and cold winter mornings.

These hydroelectric facilities were built during a 73-year period – spanning 1910-1983. The company continues to look for ways to increase its renewable hydro energy production through improved turbine efficiency – getting more energy from the same amount of water. Alabama Power has increased its renewable hydro capacity by 77 megawatts since 1997. Because of this and the state’s abundance of water resources, Alabama ranks sixth in the nation for renewable energy potential, according to the U.S. Energy Administration. Today, hydroelectric facilities are operated to balance a number of local and state needs beyond that of energy production, but this clean, renewable resource will remain an important part of the state’s energy production.

By Brandon Glover