ABSTRACT
Approximately 70 per cent of the earth’s surface is covered with water, a resource that has been exploited for many centuries. Many tens of thousands of watermills were in regular use across Asia and Europe by the 18th century, mostly for milling grain. They ranged from simple Norse wheels (25,000 of which are still in use in Nepal) to sophisticated waterwheels fitted with speed-governing mechanisms. Challenged by coal-fired steam engines in the 19th century, however, hydro-power had to become faster and more efficient. For centuries, civilizations have taken advantage of the power of water. Once used by Greeks to grind wheat into flour, the water wheels of the past have been updated to today’s highly efficient turbines that generate electricity by a spin of water. Small hydropower, defined by installed capacity of up to 10MW, 1 is the backbone of electricity production in many countries in the EU.
