How water turbines work

The simple technology that harnesses the immense natural power of water

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Water wheels have been around for several thousand years, the concept of using water to power basic machinery like mill wheels (essentially harnessing the Earth’s gravity) being well within the grasp of ancient engineers. Turbines are the next natural technological evolution of the water wheel and, although the Romans sometimes used a form of turbine for their water wheels and agricultural uses, it wasn’t until the Industrial Revolution (circa 1750-1850) that the first modern turbines emerged.

Turbines are essentially propellers in reverse, both of which work in direct accordance to Isaac Newton’s third law – namely, for every action there has to be an equal and opposite reaction. In propellers, that means energy is put into a spindle of asymmetrical blades that puts pressure on the air or water, which pushes back to propel the vehicle.

Turbines are usually fixed in place, so when a fluid flows through it there is a drop in pressure at the back edge of each blade that causes the turbine to turn. The principle is the same for air or water and the faster the medium is moving, the greater the pressure drop, and the faster the turbine spins.

It’s a much more efficient method than water wheels that yields greater hydraulic head (ie the amount of force the water can generate) with smaller apparatus. Historically turbines directly drove the huge factories of the 19th century, but since the dawn of electricity, they’re used to generate power that can be stored or passed on to the national electrical grid for a clean and renewable source of power.

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