Water

Most of Meridian Energy's electricity is made from the energy of falling water.

• The water, falling through a pipe called a "penstock", is used to spin a turbine.
• Turbines look like large wheels with wide spokes. The water hits the blades and pushes them to make the turbine spin.
• The spinning turbine spins the generator which generates the electricity.
• This spinning therefore "changes" the force of falling water into electricity.

It's not possible to store large amounts of electricity. But it is possible to store water in dams to ensure a constant supply. The lakes behind the dams store water until it's needed.

Hydro lakes are also useful and attractive venues for swimming, boating, fishing and other recreational activities.

New Zealand's first hydro dam

New Zealand's first public hydro electricity generating station went into operation in 1887. It turned on the first public electric lighting system all over Reefton on the West Coast of the South Island.

About 35 years later, at Lake Coleridge in Canterbury, the first storage lake scheme was completed.

The dam at Waitaki power station, down-river from the later Benmore and Aviemore dams, was excavated almost entirely with picks and shovels. It was the last "hand-built" dam in New Zealand.

Modern power stations – built with the latest earth-moving and digging machines – are large and impressive structures.