THE POWER OF WATER

We're hooked on fossil fuels. But hydroelectric power is becoming an increasingly important replacement for coal and oil

- IAN OSBORNE

Hydroelectric power meets around 15 per cent of the world’s electricity needs, supplying about a billion people with power – that’s comparable to 3.6 billon barrels of oil. The importance of hydropower will grow over the coming decade, with a huge number of major schemes currently under construction – as of February 2024, there are at least five in China alone. It means that although our reliance on fossil fuels is still significant – it’s a hard addiction to crack, after all – hydropower is helping us decrease our dependence.

Power production is simply a process of converting energy from one form to another. In hydroelectric plants, it’s the ‘potential energy’ of water collected in a dam that eventually ends up as electricity. A pipe known as a penstock runs through the base of the dam. As water rushes through, the potential energy becomes kinetic energy – the energy of motion. This kinetic energy rotates a turbine in the penstock.

The turbine leads to a shaft that in turn leads to a generator. Inside the generator, huge magnets start to rotate past copper coils to produce alternating current (AC) electricity.

Finally, this is changed to a higher voltage using a transformer and delivered to the power grid.

Although initial construction is expensive, once up and running, hydroelectric generators are cheap to run, produce zero waste and don’t generate any pollution. There are over 1,500 hydroelectric power plants in use in the US alone, making it the country’s largest renewable energy source. One such plant is located on the Hoover Dam, spanning the Colorado River on the border between Arizona and Nevada. When the dam was completed in 1936, it supplied Las Vegas with the majority of its electricity, though the city has since expanded and now has to get energy from other sources as well.